Article: 97016 of rec.radio.amateur.homebrew From: Paul Keinanen Subject: Re: mixer: DBM or dual gate mosfet? Message-ID: <1bns22tov5838pb8u5628sc41oi5bp2hvf@4ax.com> References: <1143306639.128205.81900@g10g2000cwb.googlegroups.com> <1143365668.224763.298690@i40g2000cwc.googlegroups.com> <1143467317.326966.226250@e56g2000cwe.googlegroups.com> <1143578181.356316.130880@j33g2000cwa.googlegroups.com> <1143880831.700873.159020@g10g2000cwb.googlegroups.com> Date: Sat, 01 Apr 2006 14:07:19 +0300 On 1 Apr 2006 00:40:31 -0800, "Giancarlo Gian Moda, I7SWX" wrote: >Hi Paul, > >This installation was somewhere on the Andes were there was a >astronomic site. Apparently this was much before the Atacama site in Chile became popular. >We did not need to use extra fans or other "helping" devices. Certainly >this set-up >was not on an open air site, it was in an building. So "air" presence >was OK for humans. At sea level, the air density is about 1.2 kg/m³ and at altitudes of 4000 m (La Paz?), the air density is only 0,8 kg/m³. In a forced cooled system, the critical parameter is the _mass_ flowing though the system and the amount of degrees the air is heated. In order to run the same mass of air through the system, you would have to use 1.2:0.8 or 1.5 times the air volume in the mountains. >BTW, in 1966 while working in UK for a small specialized company, I was >involved in a project were we were producing the Eidofor Colour TV >Projectors (Philips Group). Philips had sold 3 of these units to be >used in Mexico City for the Olympic Games. To be sure we would not have >problems with the 3 colour tubes for explosion (I forgot M.C. height >a.s.l.) we tested the system in the BAC UK air chamber (vy expensive >tubes...hi). Wasn't Eidophores used during the Apollo flights to show the orbits in Huston ? Paul OH3LWR From "know code" Sat Apr 1 19:17:40 EST 2006 Article: 97017 of rec.radio.amateur.homebrew Date: Sat, 01 Apr 2006 19:01:10 +0200 From: know code Reply-To: "know code" User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 Newsgroups: uk.radio.amateur,rec.radio.amateur.policy,rec.radio.amateur.homebrew,rec.radio.amateur.misc Subject: Re: The weeekly FAQ - What Is Ham Radio? References: <1143821165.443067.147440@e56g2000cwe.googlegroups.com> <1143907034.553864.108030@v46g2000cwv.googlegroups.com> In-Reply-To: <1143907034.553864.108030@v46g2000cwv.googlegroups.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Lines: 25 Message-ID: <442eb15c$0$16132$dbd4b001@news.wanadoo.nl> Organization: Wanadoo NNTP-Posting-Date: 01 Apr 2006 16:59:08 GMT NNTP-Posting-Host: s5591cd23.adsl.wanadoo.nl X-Trace: 1143910748 dr6.euro.net 16132 85.145.205.35:1964 X-Complaints-To: abuse@wanadoo.nl Path: news.unc.edu!canoe.uoregon.edu!newshub.sdsu.edu!tiscali!newsfeed1.ip.tiscali.net!border2.nntp.ams.giganews.com!nntp.giganews.com!news2.euro.net!postnews2.euro.net!news.wanadoo.nl!not-for-mail Xref: news0.isis.unc.edu uk.radio.amateur:269828 rec.radio.amateur.policy:257790 rec.radio.amateur.homebrew:97017 rec.radio.amateur.misc:273209 Plod's Conscience wrote: > The shortness of the list of responses is good and would > seem to suggest that the Nugatory Numpties have at long > last desisted from their rather silly and infantile tirades and > that the field is left open for _REAL_ Radio Hams to > congregate here once again. Loads of BS snipped.... I see you are also short on responses to this list of questions that were asked of you earlier today. Care to answer them or are you going to be a hypocrite all your life? Plods Reunited wrote: > Do you shag sheep? > Have you ever shagged a sheep? > Do you entertain thoughts of shagging a sheep? > Does wearing a wooly jumper give you a hard-on? > Do you masturbate wearing said jumper? > How many times a week are you sober? And your answers are? Simple "yes" or "no" answers (sound familiar?) will be fine, except for the last one where a simple figure will suffice. Or are you going to run away with your tail between you legs like you accuse Brian of doing? Article: 97018 of rec.radio.amateur.homebrew From: Ted Subject: Re: Eddystone dial and Nugatory Numpties? Message-ID: References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143078209.572601.98310@i40g2000cwc.googlegroups.com> <1143923389.579565.280640@e56g2000cwe.googlegroups.com> Date: Sat, 01 Apr 2006 17:45:58 -0500 Don, et al, Comments in-line: On 1 Apr 2006 12:29:49 -0800, dkelly42@cox.net wrote: >Ted, Dale, Ken, > >Ken that is true about the hen's teeth. I think that price is worth it >though. Dales receiver looks like a 2B. The blue backlighting is really >cool. Dale's receiver looks like it belongs in a hospital, inside the case, anyway...I'm sure an artificial liver or whatever doesn't have any more "tubing" connections! That's taking the art of modular construction to a whole 'nother level! The receiver also looks very "sanitary", as we used to say back in the '70s, or I guess the word would be "sick" in today's vernacular. More hospital tie-ins, yuk-yuk! >I just like making homebrew verniers and dials but am getting lazy and >have been using Jackson Bros.stuff for the last two projects. I tried >what I believe is an Oren Elliot drive but it is so stiff I didn't use >it. One of the last projects used a small CD for the dial. Looks clever >and homebrewish but kinda tacky too. I am dangerous with certain tools >in my hands so I try to use ready made stuff. But the dial on my SSB >transceiver needed a little more work due to the way the dial had to >mounted. I am pleased with my mechanically challenged self. I'll follow >Dales and your advice and create it on my PC. Sharpy usually used here. I won a door prize at the last NoGa meeting of a National Velvet vernier. I don't have it handy for the number, but it's a fairly small one...the dial area is about 3" wide. The cardboard scale has been humidified somewhere along the way, so I'll need to scan that and redo it in photoshop. The gears are ok, but a bit stiff. It looks like it will be perfect for a VFO, maybe my long-wanted heterodyne VFO for the HT-40. >Ted, on the VFO I roughly calculate the L and C from a few old DeMaw >and Hayward publications. But I generally go for less L more C. I think >those calculations are rough approximations anyways. I think the 2nd >edition of DeMaws QRP Notebook has the rough equations for Colpitts and >Clapp. I haven't seen one for Hartley. I have several old toroids wound >that I use for various things like VFO's. I used a number in the >Huffpuff circuit Hans Summers designed and substituted for >experimentation and optimum performance. I also have a bunch of cut and >try capacitors I use when I am building something like a VFO. I am >afraid to admit I do a lot of empirical construction on VFO's. Just the >opposite on filters and amplifiers. I use my SA when I build LC filters >and I measure all my critical L and C with my homebrew LC meter. >One thing I learned was to use ugly construction on my VFO's. I don't >know the fellow but W7EL mentioned something somewhere that made me try >that method. It simpler at the very least. >From what I understand, all other things being equal, the inductor is more likely to suffer the effects of temperature-induced drift than the capacitors, as long as C0G/NP0 and polystyrene caps are used. Therefore, it makes sense to have a higher C to L ratio, although the configuration of the VFO circuit will probably impose limits, as in failure to oscillate at some point. I generally look at somebody else's design as a prototype, and try to work around the same ratiios. I went over and over the calculations again, and I'm pretty sure I'm right, and there's a typo in the "Progressive Receiver" appendix. Then it suddenly occurred to me, " Why don't you just lash up the capacitors and the inductor and measure the darn thing?" Duh! I have a grid dip meter, and I'm still making use of my cheap-but-fairly accurate Rainbow capacitance meter, the one from the Handbook, until I get the PIC programmed for the "Everyday Practical Electronics" one that the Columbus QRP club built. This mystery will soon be solved! >Ted maybe I'll catch you on the other site but did you get the VFO >working? I knew you were working on a Hartley Huff Puff VFO. I tried >link coupling on the output from my Pierce version from the coil and >was suprised at how much cleaner the output was. I was going to try the >control circuit from a link too but had my grandson over the last two >weekends. He is just discovering his feet and rolling over. It is an >important time for grandpas. One of the Hartley designs I'm looking at for the LO of my EMRFD transceiver project is the Fig. 6.148 4 MHz one, which I would conver to 5 MHz. Now that one is tapped, but what you did Don was to not tap the coil, but to add a coupling winding, as I understand it. In the Figure I just mentioned, Wes has an MV209 on the tap for fine tuning, so I guess that's where the Huff and Puff would attach. The other circuit I've been studying to the point of actually cadding it, is Figure 12.25 in EMRFD. That one also has the familiar C1 C2 C3 Cvariable issue I've been trying to figure out, as does the Hartley above. This VFO is a Colpitts, though (I guess; the output is off the gate alone, and not the source). I suppose I'd either tap onto the coil or use a coupling winding on that one, similar to what you did. Conveniently, this one is a 5 MHz VFO already. I just put in the order to Digi-Key a couple of days ago for the chips for the fast stabilizer, so no, I haven't built it yet. I decided not to go ahead with the other 2-chip minimalist one after your suggestion on the fast one. The crystal oscillator I ordered is 66.66 MHz, so it should work. >Its spring yardwork weekend here so not much radio going on. BTW, what >is a Nugatory Numptie (see other post)? I could be one. Do we have a >website? > >K5UOS I've got to go back and look at the other post. Don't know how I missed that! Ted KX4OM Article: 97019 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143321832.545680.142220@g10g2000cwb.googlegroups.com> <1143385239.766015.160760@i39g2000cwa.googlegroups.com> <8h3h22582psr78h3n6iq7q3thdgr628c1d@4ax.com> Subject: Re: Eddystone dial and custom dial plates Message-ID: Date: Sun, 02 Apr 2006 02:20:25 GMT Hi Don and Ted, While it has been over a year now since I did the VFO- I too had some difficulties with the QST values. In talking w/ W7ZOI, Wes indicated that some errors had worked their way into the design over the years. One was on the audio amp- values I had caused severe rolloff below about 2KHz- making SSB very tinny. The other was on the VFO. Because of the Eddystone dial, I wished to make the VFO as linear as possible- book values led to a highly non linear scale. I do not recall exactly what I did- although I played with the math for a long time- to lienarize it- but I would trust your calcs. At some point I will open her up again as I want to buffer the VFO and tap off for a TX VFO- the plan is to build a Drake style reciter for the RX- and at that time will better document the changes I made. Dale W4OP Article: 97020 of rec.radio.amateur.homebrew From: "Paul VK3DIP" References: <1142687392.568430.122110@e56g2000cwe.googlegroups.com> Subject: Re: Return Loss Bridge Accuracy Questions Message-ID: <7SLXf.22113$dy4.15868@news-server.bigpond.net.au> Date: Sun, 02 Apr 2006 08:23:31 GMT Hi Steve, If you are interested I had really good results recently with a homebrew RLB, in fact so good that I doubted the results and had to redo them several times before I was comfortable I hadn't made a mistake, and I probably still have but anyway it works heaps good enough for me. Basically using the non lab standard test equipment I had available it shows a directivity of better than 40db from about 1 to 500MHz. I found the best results by using a more or less current balun with coax, and a balancing extra bit of coax, and paying close attention to keeping everything balanced/symmetrical and having the reference connected with a connector identical to the unknown, rather than just a 50ohm resistor directly connected. See writeup in December issue of Nerg News http://www.nerg.asn.au/NERGNEWS/NN200512.pdf 73 Paul VK3DIP. wrote in message news:1142687392.568430.122110@e56g2000cwe.googlegroups.com... >I have just built an HF return loss bridge according to the info in > "Solid State design for the Radio Amateur". While it works ok, I was > hoping for a bit better performance. Clearly the "balun" doesn't have > enough inductance to operate well below 10 MHz or so (10 turns bifilar > #30 AWG enamelled wire on Amidon T23-43, as specified in the book - > twisted pair, which isn't specified one way or the other in the book). > This can probably be largely fixed by using a larger ferrite core > (T37-43's available in junkbox). I am interested primarily in the > 1.8-50 MHz range, though I wouldn't complain if it worked on 2m too. > > But even at 30 MHz a reasonably good microwave 50 ohm load gives only > about 28 dB apparent return loss...Not bad, but I might have expected a > bit more. > > And an open and short give about 2 dB different signal levels at 30 > MHz. That is with big pads (>20 dB attenuation) on both the signal > generator and detector. The detector is an HF receiver with a step > attenuator used to maintain a constant S-meter reading. > > The circuit is built on a small PC board using construction techniques > typical for the UHF or low microwave range (except that the test port > connector is an SO-239), and is enclosed in a shielded box. Each of > the three 50 ohm resistors is made of two 100 ohm 1206 chip resistors > in parallel and measures between 50.0 and 50.3 ohms at DC. > > Has anyone with experience with this circuit any suggestions for how to > tweak it for best performance ? What accuracy level have you achieved > ? Do you know where I might find an error analysis for this circuit ? > Or if I am to think about errors myself, does anyone know how to model > the balun in SPICE ? > > 73, > Steve VE3SMA > Article: 97021 of rec.radio.amateur.homebrew From: Rob Subject: Z Match Message-ID: Date: Sun, 02 Apr 2006 11:10:18 GMT Does anyone have a link to a website for making a high power Z match? I have made the 100 watt version with the toroid core and broadcast caps which really works great. I thought maybe there might be a design out there using heavier toroids for more wattage (500-1000 watts). Thanks for any info, Rob Article: 97022 of rec.radio.amateur.homebrew From: larry d clark Subject: Re: Z Match References: Message-ID: <1nOXf.61517$H71.5931@newssvr13.news.prodigy.com> Date: Sun, 02 Apr 2006 11:15:09 GMT Rob wrote: > Does anyone have a link to a website for making a high power Z match? I > have made the 100 watt version with the toroid core and broadcast caps > which really works great. I thought maybe there might be a design out > there using heavier toroids for more wattage (500-1000 watts). Thanks > for any info, Rob > http://www4.tpgi.com.au/users/ldbutler/SingleCoilZMatch.htm larry kd5foy From "know code" Wed Apr 5 22:45:19 EDT 2006 Article: 97023 of rec.radio.amateur.homebrew Date: Sun, 02 Apr 2006 16:33:51 +0200 From: know code Reply-To: "know code" User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 Newsgroups: uk.radio.amateur,rec.radio.amateur.policy,rec.radio.amateur.homebrew,rec.radio.amateur.misc Subject: Re: The weeekly FAQ - What Is Ham Radio? References: <1143821165.443067.147440@e56g2000cwe.googlegroups.com> <1143907034.553864.108030@v46g2000cwv.googlegroups.com> <442eb15c$0$16132$dbd4b001@news.wanadoo.nl> In-Reply-To: <442eb15c$0$16132$dbd4b001@news.wanadoo.nl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Lines: 32 Message-ID: <442fe055$0$81653$dbd4b001@news.wanadoo.nl> Organization: Wanadoo NNTP-Posting-Date: 02 Apr 2006 14:31:49 GMT NNTP-Posting-Host: s5591cd23.adsl.wanadoo.nl X-Trace: 1143988309 dr6.euro.net 81653 85.145.205.35:3693 X-Complaints-To: abuse@wanadoo.nl Path: news.unc.edu!canoe.uoregon.edu!cyclone1.gnilink.net!gnilink.net!nx01.iad01.newshosting.com!newshosting.com!83.128.0.11.MISMATCH!news-out1.kabelfoon.nl!newsfeed.kabelfoon.nl!xindi.nntp.kabelfoon.nl!news2.euro.net!postnews2.euro.net!news.wanadoo.nl!not-for-mail Xref: news0.isis.unc.edu uk.radio.amateur:269879 rec.radio.amateur.policy:257817 rec.radio.amateur.homebrew:97023 rec.radio.amateur.misc:273220 know code wrote: > Plod's Conscience wrote: >> The shortness of the list of responses is good and would >> seem to suggest that the Nugatory Numpties have at long >> last desisted from their rather silly and infantile tirades and >> that the field is left open for _REAL_ Radio Hams to >> congregate here once again. > > Loads of BS snipped.... > > I see you are also short on responses to this list of questions that > were asked of you earlier today. Care to answer them or are you going > to be a hypocrite all your life? > > Plods Reunited wrote: > > Do you shag sheep? > > Have you ever shagged a sheep? > > Do you entertain thoughts of shagging a sheep? > > Does wearing a wooly jumper give you a hard-on? > > Do you masturbate wearing said jumper? > > How many times a week are you sober? > > And your answers are? Simple "yes" or "no" answers (sound familiar?) > will be fine, except for the last one where a simple figure will > suffice. Or are you going to run away with your tail between you legs > like you accuse Brian of doing? I see Beanie is a hypocrite who has ran away with his tail between his legs as he still hasn't answered the questions! Was it not Beanie that said something along the lines of you are proven guilty by your silence? Ho hum. Article: 97024 of rec.radio.amateur.homebrew From: MetalHead Subject: Re: Expanded UTC Page References: Message-ID: Date: Sun, 02 Apr 2006 21:41:46 GMT Brian Webb wrote: > Hello: > > I have recently expanded the Coordinated Universal Time (UTC) page on my web > site (http://www.spacearchive.info/utc.htm). > > I would appreciate it if you would carefully read the page for technical > accuracy and send me your comments. > > Regards, > > Brian W., KD6NRP > > Brian, What I read of it looked good. On your section on GPS time, you might note that GPS time does not include the leap-seconds that clock time does. I believe that there are now 14 leap seconds difference between GPS time and clock time, but that should be verified (it might be 16). The handheld GPS receivers I have seen, correct for the difference before displaying the time. Industrial units may provide either at your option. I believe that you can get 50 nS accuracy out of the industrial units (specifically the old Motorola Oncore series). Regards, Bob KE7FEF Article: 97025 of rec.radio.amateur.homebrew From: MetalHead Subject: Re: Expanded UTC Page References: Message-ID: Date: Sun, 02 Apr 2006 21:53:47 GMT MetalHead wrote: > Brian Webb wrote: > >> Hello: >> >> I have recently expanded the Coordinated Universal Time (UTC) page on >> my web >> site (http://www.spacearchive.info/utc.htm). >> >> I would appreciate it if you would carefully read the page for technical >> accuracy and send me your comments. >> >> Regards, >> >> Brian W., KD6NRP >> >> > Brian, > What I read of it looked good. On your section on GPS time, you might > note that GPS time does not include the leap-seconds that clock time > does. I believe that there are now 14 leap seconds difference between > GPS time and clock time, but that should be verified (it might be 16). > The handheld GPS receivers I have seen, correct for the difference > before displaying the time. Industrial units may provide either at your > option. I believe that you can get 50 nS accuracy out of the industrial > units (specifically the old Motorola Oncore series). > > Regards, > Bob > KE7FEF I was curious and looked it up, as of Jan 1, 2006 GPS time leads clock time (UTC) by 14 seconds. There is a good web page here: http://tycho.usno.navy.mil/leapsec.html Regards, Bob KE7FEF Article: 97026 of rec.radio.amateur.homebrew From: Ted Subject: Re: Eddystone dial and custom dial plates Message-ID: References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143321832.545680.142220@g10g2000cwb.googlegroups.com> <1143385239.766015.160760@i39g2000cwa.googlegroups.com> <8h3h22582psr78h3n6iq7q3thdgr628c1d@4ax.com> Date: Sun, 02 Apr 2006 20:16:29 -0400 Dale & Don, I haven't had a chance to lash up the components yet, but I checked my spreadsheet using Wes's example on page 4.4. The numbers check out; unfortunately, Wes specifies a value for C3 in the EMRFD example, and in the Progressive Receiver Article, C3 is the unknown; i.e., how much additional capacitance you'd have to add in parallel with the coil to use a specific variable cap in the given configuration. Now that I can see the "C12v" equation in EMRFD, which is not in the QST article, but I've modified my spreadsheet to include it I can check the resonance using the given values for L. Dale, when I looked at your jpg's again yesterday, I noticed that you've modified the receiver internals a lot since I first saw the rig. Since the links I had were to a directory on your commercial site, I'm not sure if you have another site where you described what you did. Early last Spring, I got rid of all my new-fangled ham rigs, like the FT-817 and the not-so-new, but pristine TS-530s and bought an HW-101 and some equipment to restore. Homebrewing and boatanchors is what I'm about now. I did the VFO alignment on the HW-101 and was able to get it within 1kHz, end to end, as indicated on the dial, anyway. That surprised the heck out of me. I've since acquired an LMO from an SB-401 that I'm going to put in a project somewhere along the line. I have a complete set of Heath HFO crystals, and both CW and SSB filters >from another source. I might make myself a broadbanded QRP rig out of those. 73, Ted KX4OM On Sun, 02 Apr 2006 02:20:25 GMT, "Dale Parfitt" wrote: > Hi Don and Ted, >While it has been over a year now since I did the VFO- I too had some >difficulties with the QST values. In talking w/ W7ZOI, Wes indicated that >some errors had worked their way into the design over the years. One was on >the audio amp- values I had caused severe rolloff below about 2KHz- making >SSB very tinny. >The other was on the VFO. Because of the Eddystone dial, I wished to make >the VFO as linear as possible- book values led to a highly non linear scale. >I do not recall exactly what I did- although I played with the math for a >long time- to lienarize it- but I would trust your calcs. >At some point I will open her up again as I want to buffer the VFO and tap >off for a TX VFO- the plan is to build a Drake style reciter for the RX- and >at that time will better document the changes I made. > >Dale W4OP > Article: 97027 of rec.radio.amateur.homebrew From: Ted Subject: Re: Eddystone dial and Nugatory Numpties? Message-ID: <6bq032p96ccnalcpo9fimo170mklm3sbpl@4ax.com> References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143078209.572601.98310@i40g2000cwc.googlegroups.com> <1143923389.579565.280640@e56g2000cwe.googlegroups.com> <1143935706.908200.190290@z34g2000cwc.googlegroups.com> Date: Sun, 02 Apr 2006 21:00:04 -0400 On 1 Apr 2006 15:55:06 -0800, dkelly42@cox.net wrote: >Using those old verniers is risky to me only because finding >replacements if they start to slip or have backlash. I at least try to >find or build something I can replace. But the Eddiestone are just so >nice looking. Well, maybe this one WILL be nice looking :) > >What I did on the HP VFO was like in fig 7.27 EMRFD. The output of the >IC is a square wave. I was concerned after I looked at the output on my >analyzer. I see why the cmos marker generators are so popular. Strong >harmonics way above 100MHz. The output was significantly cleaner from >the tap. Right around then I decided to go back and finish my SSB >receiver and mount it in the chassis so I didn't have to use so many >clip leads while I was playing with it. Figure 7.27? I don't quite follow that, unless you're talking about how you've band-switched it. > >I was going to do something similar to the fig 12.25 mixing type LO and >I still may. My original receiver had a 9MHz filter but a relatively >strong birdy from the LO at 7.2MHz. I decided to just change the filter >to 9.216MHz and no birdies. Was hell trying to find closely matched >9.216MHz crystals though. I got 65 ea from Mouser and only got ten >within 5%. Mostly a wide discrepancy in ESR. I guess you can make up >for a lossy filter but after spending as much time as I did on both >filters in measuring crystals I wanted something to show for it. I'm using that design because I'll need 2 HFO's in two separate rigs I'm working on. That one is interesting because of the 5 MHz output, but I won't be using that for the rig itself. I'm using a 74HC4053 switch to mix either of two LOs with the 5 MHz VFO. The transceiver I'm using EMRFD circuits for is a 15 and 20 meter SSB/CW traansceiver. I'm using a 9MHz If, with HFO frequencies of 25 and 18 MHz. I'll use the sums to produce the correct LO frequencies. The other rig is one I've been working on, off and on, for over a year. That one is based on G4GXOs Belthorn SSB/IF module. I picked an IF of 11 MHz for it, because 32 and 25 MHz HFO crystals will allow me to use a VFO of the toal span of 3.890 4.148 MHz. All of the crystals are Mouser 39-cent variety. I didn't realize it, but when I put in my order from Digi-Key last wee, I stumbled across the ECS 18 MHz crystal, a value I didn't have in my data base of available frequencies...that allows me to make the EMRFD rig a 2-bander, adding 20 meters! >I was going to try the control circuit on the tap in my HP VFO. I know >it will work thiough even though I haven't tried it. Its just getting >the correct link and varactor. The fast HP VFO's still amazes me. >I get started on too many things so I went back to my SSB rig. > >On the inductor drift I agree. I seem to have luck with slightly lower >L and using the slight neg temp coefficient of the COG caps. I did that >in my tube receiver built with toroids. I ended up using a small silver >mica for temp compensation of all things. Like you I look at other >circuits and copy. I didn't on this VFO because I was copying my own >circuit that worked before from something I am sure I copied. The more >I try other things though the less I copy. Right now I am working on a >25 VDC 6AMP power supply for the transceiver. I am going to try power >mosfets again as I had good luck in the last low power linear I built. >I am only looking for 40W or so. Plenty big for the type of SSB I will >work. I have a 28 VDC 3 A supply I made years ago. Just not sure it is >big enough for the PA I am going to use. Its not that efficient. > >Gosh, typo errors in ham publications! Hard to believe! Not!. Good for >you for checking. I have a mess of spreadsheets with most of the common >formulas. I also made some for double and triple tuned BP filters, >feedback amps, my LC meter calculations, a logarithmic power meter and >crystal parameter testing. I check a lot of circuits in books by >plugging in the data to my sheets. > >EMRFD is a great book. One thing I have been using in my transceiver LO >now is the hybrid splitter shown in fig 6.75. The vfo in 12.25 shows a >resistive version. I used the hybrid on both my VFO and BFO. That is a >nice technique even if it is a few more parts. I guess Wes must be a >better Numptie than all of us? I'm not sure I really knew much of anything until I got EMRFD. The first few weeks, I had a running stream of Q&A emails with Wes, and he was kind enough to be patient and explain some things. One in particular was a problem I had in adapting a published L-network to the actual impedances of my crystal filter in the 30 meter rig I built for Straight Key Night . In Fig. 12.25, he's actually using the take-off point from the VFO to the mixer from the attenuator pad for the 5 MHz output, to get the -10 dBm for 5 MHz for the 20 meter part of the rig. >I bet you will really enjoy experimenting with the fast HP VFO. I >haven't had that much fun with a simple project in a long time. Once >you build a few you start getting alot of ideas on how to use it. Then >it starts adding to your list of projects. You start losing sleep, the >wife keeps asking you to take the trash out, you stop shaving, grow >your hair long and start smoking and drinking too much coffee. Then you >are in Nugatory. Thats ham purgatory. My wife calls it the doghouse. Sleep? What's that? Fortunately, my wife is busy getting her business up and running, and I have plenty of time on my hands (I've inherited the dog and cat-tending responsibilities). >Maybe I will put a picture of my progress on the SSB transceiver on the >tech site soon. I never know what Chuck is willing to accept though. So >I get a little cautious. I understand completely. However, why not start a folder anyway? There's only a couple of them there, and it's not like it's stuff that belongs in the Smithsonian. Now if Dale had his receiver on the site, that's certainly Smithsonian-quality! When I was building the SKN Special, I did running updates to the NoGa list with the latest photos on my web site. Now that it's finished, I recently went back and reorganized that page to reflect past tense. One of the highlights was definitely getting the VFO going. On the scope, the signal has a weird distortion in the sine wave, like the trailing edge is partially scooped out; I should post that on the yahoo group site and see if anyone can figure out what it means. But, since it's feeding an NE602, and they can take square waves, I guess a little distortion doesn't matter. >Keep me up on your progress. Tomorrow, I lash up a test capacitance circuit. Then, once I can finally do the math and figure out which variable I can use, I'll start building. the Digi-Key prts for the Huff and Puff whould be here mid-week. 72/73, Ted KX4OM Article: 97028 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143321832.545680.142220@g10g2000cwb.googlegroups.com> <1143385239.766015.160760@i39g2000cwa.googlegroups.com> <8h3h22582psr78h3n6iq7q3thdgr628c1d@4ax.com> Subject: Re: Eddystone dial and custom dial plates Message-ID: Date: Mon, 03 Apr 2006 01:37:23 GMT "Ted" wrote in message news:mgo032dq2loeg8mkb708qi044rv1nqt70h@4ax.com... > Dale & Don, > I haven't had a chance to lash up the components yet, but I checked my > spreadsheet using Wes's example on page 4.4. The numbers check out; > unfortunately, Wes specifies a value for C3 in the EMRFD example, and > in the Progressive Receiver Article, C3 is the unknown; i.e., how much > additional capacitance you'd have to add in parallel with the coil to > use a specific variable cap in the given configuration. > Now that I can see the "C12v" equation in EMRFD, which is not in the > QST article, but I've modified my spreadsheet to include it I can > check the resonance using the given values for L. > > Dale, when I looked at your jpg's again yesterday, I noticed that > you've modified the receiver internals a lot since I first saw the > rig. Since the links I had were to a directory on your commercial > site, I'm not sure if you have another site where you described what > you did. > > Early last Spring, I got rid of all my new-fangled ham rigs, like the > FT-817 and the not-so-new, but pristine TS-530s and bought an HW-101 > and some equipment to restore. Homebrewing and boatanchors is what > I'm about now. I did the VFO alignment on the HW-101 and was able to > get it within 1kHz, end to end, as indicated on the dial, anyway. That > surprised the heck out of me. I've since acquired an LMO from an > SB-401 that I'm going to put in a project somewhere along the line. I > have a complete set of Heath HFO crystals, and both CW and SSB filters > from another source. I might make myself a broadbanded QRP rig out of > those. > > 73, > Ted KX4OM > Hi Ted, I quickly looked at the VFO schematic in my1994 Handbook that had the PR. I seem to recall in the end I replaced C1 with a short- just eliminating it. Not 100% positive, but think that was what it came down to in order to get good linearity out of my VFO. Dale Article: 97029 of rec.radio.amateur.homebrew Date: Mon, 03 Apr 2006 21:12:59 +0800 From: Richard Hosking Subject: QRP 5W HF linear amp transistors and design Message-ID: <44311f5c$0$2111$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Dear all I want to build a power amp for SSB HF 1.5-30 MHz Specs approx 5W out Cheap/easy to source components Surface Mount parts/small Rugged/stable into any/most loads Gain around 40 dB Flat gain to 1 dB or so Thought I would do something like Class A MMBT2222 -> 2X push pull MMBT2222 -> finals push pull balanced What to do for the finals? I looked at the PD55003 RF MOSFETS - can you get these easily? Will they work down to HF? What other issues? What about transformers? Is this a practical proposition? I havent seen any similar designs I would be grateful for some pointers Thanks Richard Article: 97030 of rec.radio.amateur.homebrew From: Allison-nospam@nouce.bellatlantic.net Subject: Re: QRP 5W HF linear amp transistors and design Message-ID: <1ne2325vph1edmktud7pjbdlp7jsgvg1d6@4ax.com> References: <44311f5c$0$2111$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Date: Mon, 03 Apr 2006 15:13:58 GMT On Mon, 03 Apr 2006 21:12:59 +0800, Richard Hosking wrote: >Dear all >I want to build a power amp for SSB HF 1.5-30 MHz >Specs > approx 5W out > Cheap/easy to source components > Surface Mount parts/small > Rugged/stable into any/most loads > Gain around 40 dB > Flat gain to 1 dB or so > >Thought I would do something like > >Class A MMBT2222 -> 2X push pull MMBT2222 -> finals push pull balanced > >What to do for the finals? >I looked at the PD55003 RF MOSFETS - can you get these easily? >Will they work down to HF? > >What other issues? >What about transformers? >Is this a practical proposition? >I havent seen any similar designs > >I would be grateful for some pointers > >Thanks >Richard You need a stiffer driver than 2222. Common CB finals 2sc1971, 1909, 799 and other are all good for that power level and easily run to 30mhz (some to 6m!). I've found power fets hard to make gain flat over that range. Plan on a fair bit of feedback to stabilize the gain. EMRFD, Experimental Methods in RF Design (arrl press) has a few circuits suited or as base examples. Allison Article: 97031 of rec.radio.amateur.homebrew From: lawrence@hummer.not-here.net Subject: Re: Expanded UTC Page Date: 03 Apr 2006 11:04:29 -0700 Message-ID: <87acb2cz82.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> References: <1144085752.151373.127510@z34g2000cwc.googlegroups.com> "ray13" writes: > Hallo Brian: > > Am I in a time warp of some kind, or is your table all messed up. I'm > talking about your conversion of time zones Ummmm, no. > Towit you have the eastern time zone 7 hours ahead of Zulu time. My > gawd man can I get the same time machine you have? The version of the page dated 2006 April 2 has the following: PST PDT MST MDT CST CDT EST EDT UTC 4 p.m. 5 p.m. 5 p.m. 6 p.m. 6 p.m. 7 p.m. 7 p.m. 8 p.m. 00:00 Which is correct, showing the EST as being 5 hours BEHIND UTC (or 19 hours ahead if you think mod24) > Lastly your conversion table doesn't have all Canadian time zones eh? > Guess Newfoundland doesn't exist in your reality eh? > That is true -- nor does it include time zones for Alaska, Hawaii and the Aleutians. -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Lawrence Statton - lawrenabae@abaluon.abaom s/aba/c/g Computer software consists of only two components: ones and zeros, in roughly equal proportions. All that is required is to sort them into the correct order. Article: 97032 of rec.radio.amateur.homebrew From: "The Magnum" References: <1143821165.443067.147440@e56g2000cwe.googlegroups.com> <1143907034.553864.108030@v46g2000cwv.googlegroups.com> <442eb15c$0$16132$dbd4b001@news.wanadoo.nl> <442fe055$0$81653$dbd4b001@news.wanadoo.nl> Subject: Re: The weeekly FAQ - What Is Ham Radio? Date: Mon, 3 Apr 2006 19:13:48 +0100 Message-ID: <4431747f$0$20106$834e42db@reader.greatnowhere.com> "G-Whiz" wrote in message news:BMidnc6Nl9s7rK3ZRVny2w@bt.com... > On Sun, 02 Apr 2006 16:33:51 +0200, know code wrote: > > >>> Plods Reunited wrote: > >> > Do you shag sheep? > >> > Have you ever shagged a sheep? > >> > Do you entertain thoughts of shagging a sheep? > >> > Does wearing a wooly jumper give you a hard-on? > >> > Do you masturbate wearing said jumper? > >> > How many times a week are you sober? > >> > >> And your answers are? Simple "yes" or "no" answers (sound familiar?) > >> will be fine, except for the last one where a simple figure will > >> suffice. Or are you going to run away with your tail between you legs > >> like you accuse Brian of doing? > > > > > > I see Beanie is a hypocrite who has ran away with his tail between his > > legs as he still hasn't answered the questions! Was it not Beanie that > > said something along the lines of you are proven guilty by your silence? > > Ho hum. > > ISTR The Magnum asked pretty much the same: > > > > also with no answer. Should we presume? > > GW As Mr Evans has often said he never clicks on links to messages then I will repost my questions for him to see and possibly answer if he finds time away >from Harassing Brian Reay Quote.. "So tell us Mr Evans... Have you ever had improper thoughts about sheep?... (No smoke without fire etc...) And have you ever sampled the delight that is known as 'Meths' as an inebriant? And finally, have you ever 'threatened' little girls in any way?... These are the things we wish to know... " End quote, Graham -- -.-. -... / .-. .- -.. .. --- Radio is only a Hobby. Don't let it rule your life... 73/51 - Graham, 26-Golf Charlie-19 Article: 97033 of rec.radio.amateur.homebrew From: "Brian Reay" Subject: 1MHz oscillator modules Message-ID: Date: Mon, 03 Apr 2006 18:31:53 GMT Anyone know of a (ideally) UK source of 1MHz oscillator modules- the little beasts that are about the size of a 14 or 16 pin DIL package? Space for a descreet crystal and other bits is a bit tight. -- 73 Brian, G8OSN www.g8osn.org.uk Article: 97034 of rec.radio.amateur.homebrew From: dplatt@radagast.org (Dave Platt) Subject: Re: QRP 5W HF linear amp transistors and design Date: Mon, 03 Apr 2006 20:54:11 -0000 Message-ID: <12332rj5dtv2t10@corp.supernews.com> References: <44311f5c$0$2111$5a62ac22@per-qv1-newsreader-01.iinet.net.au> <1ne2325vph1edmktud7pjbdlp7jsgvg1d6@4ax.com> In article <1ne2325vph1edmktud7pjbdlp7jsgvg1d6@4ax.com>, wrote: >You need a stiffer driver than 2222. > >Common CB finals 2sc1971, 1909, 799 and other are all good for that >power level and easily run to 30mhz (some to 6m!). FWIW, the Elecraft K2 uses a single 2SC2166 as a driver, feeding a push-pull pair of 2SC1969s. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 97035 of rec.radio.amateur.homebrew From: Eamon Skelton Subject: Re: QRP 5W HF linear amp transistors and design Message-ID: References: <44311f5c$0$2111$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Date: Mon, 03 Apr 2006 22:35:24 +0100 On Mon, 03 Apr 2006 21:12:59 +0800, Richard Hosking wrote: > Dear all > I want to build a power amp for SSB HF 1.5-30 MHz Specs > approx 5W out > Cheap/easy to source components > Surface Mount parts/small > Rugged/stable into any/most loads > Gain around 40 dB > Flat gain to 1 dB or so It is hard to beat CB PA and driver transistors for this job. 2SC2166 makes a great driver. If you only need 5W, you could use them as the final stage. For slightly higher power levels, the 2SC1969 or 2SC2312 are a good choice. The 2SC1945 is particularly attractive because the HS tab is connected to the emitter rather than the collector. Genuine Mitsubishi are usually better than unbranded generic transistors. http://www.grandata.co.uk usually have the best prices for Japanese transistors. > Thought I would do something like > > Class A MMBT2222 -> 2X push pull MMBT2222 -> finals push pull balanced > > What to do for the finals? > I looked at the PD55003 RF MOSFETS - can you get these easily? Will they > work down to HF? My experience with modern devices is that you can easily get them for free as samples but you can't buy them for love nor money :-) The Philips BFGxxx series of surface-mount transistors are readily available on this side of the planet. BFG235 12V 2W and BFG135A 15V 1W have multi-GHz ft and are available from Maplin. > What other issues? Don't let the smoke out. > What about transformers? Broadband ferrite. > Is this a practical proposition? Yes. > I havent seen any similar designs Thats because we are all using CB transistors. BTW, It is nice to see you back on r.r.a.h We all missed you. 73, Ed. EI9GQ. -- Linux 2.6.15 Remove 'X' to reply by e-mail. Yes, my username really is: nospam Article: 97036 of rec.radio.amateur.homebrew From: Allison-nospam@nouce.bellatlantic.net Subject: Re: QRP 5W HF linear amp transistors and design Message-ID: <915332ppos5peeidlqnepoukunf55vmcm7@4ax.com> References: <44311f5c$0$2111$5a62ac22@per-qv1-newsreader-01.iinet.net.au> <1ne2325vph1edmktud7pjbdlp7jsgvg1d6@4ax.com> <12332rj5dtv2t10@corp.supernews.com> Date: Mon, 03 Apr 2006 21:40:55 GMT On Mon, 03 Apr 2006 20:54:11 -0000, dplatt@radagast.org (Dave Platt) wrote: >In article <1ne2325vph1edmktud7pjbdlp7jsgvg1d6@4ax.com>, > wrote: > >>You need a stiffer driver than 2222. >> >>Common CB finals 2sc1971, 1909, 799 and other are all good for that >>power level and easily run to 30mhz (some to 6m!). > >FWIW, the Elecraft K2 uses a single 2SC2166 as a driver, feeding a >push-pull pair of 2SC1969s. That's the class of devices I referred to. The 2166 and 1969 are both excellent devices and can be found cheap. I recently completed a chain for 6m. I used 2n4124, 2SC1306, 2SC1971 as I had them for an overall gain of 35db (design goal) and CW power of 4W or a two tone of 6Wpep at 13V. The goal was good IMD so the devices were run at 50% of what was possible with them power wise and stiffly biased. All of the devices were common stuff or CB pulls. Changing the circuit for a puchpull output of two 1971s would have easily done 10W carrier. Allison Article: 97037 of rec.radio.amateur.homebrew From: References: Subject: Re: Radio tracking a tortoise - help! Message-ID: Date: Mon, 03 Apr 2006 23:12:13 GMT where are you? You would be better with a small receiver and glued to Shelly and a little Ipod booster transmitter you could walk round until you heard the music playing. Get a small cheep FM radio for Shelly and just tune to your own frequency. Totally illegal in the UK of course, but who's going to come looking for you? If your in the UK that would be a cracking project for some interested ham types but they would be unwilling to break any rules. legally You could use 446 PMR about £20 a pair and some of them are tiny. Article: 97038 of rec.radio.amateur.homebrew From: "Caveat Lector" References: Subject: Re: Radio tracking a tortoise - help! Message-ID: Date: Mon, 3 Apr 2006 17:25:59 -0700 Perhaps Shelly is looking for Sheldon So get another turtle (;-) All in good fun A small transmitter and a DF receiver should do it, if you check daily on Shelly's where abouts Or do you have a fast tortise (;-) ? -- CL -- I doubt, therefore I might be ! wrote in message news:hZhYf.2655$BO5.350@newsfe3-win.ntli.net... > where are you? You would be better with a small receiver and glued to > Shelly > and a little Ipod booster transmitter you could walk round until you heard > the music playing. Get a small cheep FM radio for Shelly and just tune to > your own frequency. Totally illegal in the UK of course, but who's going > to > come looking for you? If your in the UK that would be a cracking project > for some interested ham types but they would be unwilling to break any > rules. legally You could use 446 PMR about £20 a pair and some of them are > tiny. > > Article: 97039 of rec.radio.amateur.homebrew Date: Tue, 04 Apr 2006 19:50:54 +0800 From: Richard Hosking Subject: Re: QRP 5W HF linear amp transistors and design References: <44311f5c$0$2111$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Message-ID: <44325d9e$0$2127$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Thanks all I will investigate the CB transistors R Richard Hosking wrote: > Dear all > I want to build a power amp for SSB HF 1.5-30 MHz > Specs > approx 5W out > Cheap/easy to source components > Surface Mount parts/small > Rugged/stable into any/most loads > Gain around 40 dB > Flat gain to 1 dB or so > > Thought I would do something like > > Class A MMBT2222 -> 2X push pull MMBT2222 -> finals push pull balanced > > What to do for the finals? > I looked at the PD55003 RF MOSFETS - can you get these easily? > Will they work down to HF? > > What other issues? > What about transformers? > Is this a practical proposition? > I havent seen any similar designs > > I would be grateful for some pointers > > Thanks > Richard Article: 97040 of rec.radio.amateur.homebrew From: Ted Subject: Re: Eddystone dial and custom dial plates Message-ID: References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143321832.545680.142220@g10g2000cwb.googlegroups.com> <1143385239.766015.160760@i39g2000cwa.googlegroups.com> <8h3h22582psr78h3n6iq7q3thdgr628c1d@4ax.com> Date: Tue, 04 Apr 2006 10:06:19 -0400 On Mon, 03 Apr 2006 01:37:23 GMT, "Dale Parfitt" wrote: >Hi Ted, >I quickly looked at the VFO schematic in my1994 Handbook that had the PR. I >seem to recall in the end I replaced C1 with a short- just eliminating it. >Not 100% positive, but think that was what it came down to in order to get >good linearity out of my VFO. > >Dale > Dale, I'll check that out. My value for C3 from the spreadsheet came out to be 319.1 vs the 127.02 in the magazine. I used the spreadsheet on the example on page 4.4 of EMRFd and it worked out ok. In the QST example, setting C1 to a very low value actually increases the discrepancy with C3, though. More mystery! Tnx, Ted KX4OM Article: 97041 of rec.radio.amateur.homebrew From: "Brian Reay" References: Subject: Re: 1MHz oscillator modules Message-ID: Date: Tue, 04 Apr 2006 17:15:07 GMT "Highland Ham" wrote in message news:Kc-dnZlGv5li1q_ZRVnyjA@pipex.net... > Brian Reay wrote: >> Anyone know of a (ideally) UK source of 1MHz oscillator modules- the >> little beasts that >> are about the size of a 14 or 16 pin DIL package? >> >> Space for a descreet crystal and other bits is a bit tight. >> > ===================== > Suggest you check the following potential suppliers : > > www.modecomponents.co.uk > > I-Q Electronic Design tel/fax : 0208 391 0545 > e-mail : vincent@jakomin.fsnet.co.uk > > www.jabdog.com > > Good luck A thank you to you and all who responded, I've now found a source and (hopefully) bits arrive tomorrow. -- 73 Brian www.g8osn.org.uk Article: 97042 of rec.radio.amateur.homebrew From: "Ronnie" Subject: Question about auto antenna cable and connectors Message-ID: Date: Tue, 04 Apr 2006 19:17:12 GMT Hi, This is not about ham radio, but rather a general question about the type of cable and connectors that were found between the antenna and the AM radio in GM cars in the 60's. I'm trying to locate some technical information about the cable and a source for the cable and connectors. I have an old airplane autopilot system that uses tuned circuit to sense changes in the airplane's attitude and the position of the control servos. Distributed variable inductances and variable capacitors combine to establish the resonant operating frequency of the system. The components are connected together with specific lengths of cable and the service manual points out that the lengths are critical because of the added capacitance of the cable and connectors. The cable is marked as follows: "I. T. & T. Federal Cable R.E.C." It is a shielded cable with a spiral wound center conductor that looks very much like the antenna cable I remember finding in GM cars in the 60's. It also has the same type of connectors. There is a center pin for the center conductor and a metal sleve that extents back over the cable and makes a connection with the shield and chassis of the radio. Friction holds the connector in its mating socket - there are no threads, just a couple of splayed out areas on the sleve. I was hoping one of you might be able to point me to a source of technical information about this cable, such as the capacitance per unit length, etc. The one piece I have measures about 10.5 pF / foot or 415 pF / meter, but my measurements may not be all that accurate. Also, a source where the cable and connectors can be found today would be appreciated. Thanks in advance for any help. Ronnie, N5CSE Article: 97043 of rec.radio.amateur.homebrew From: "Theo" Subject: Codar Message-ID: Date: Tue, 04 Apr 2006 21:05:43 GMT I am looking for an unmodified Codar T28 receiver in good working order, to pair up with my AT5 transmitter. Any assistance to locate one would be greatly appreciated. Theo Article: 97044 of rec.radio.amateur.homebrew From: Skipp is here Subject: Want a Maxcom Antenna Matcher (stop laughing please) Date: Tue, 4 Apr 2006 22:13:46 +0000 (UTC) Message-ID: Re: Want a Maxom Antenna Matcher I'm looking for one of the Maxcom Antenna Matcher Units. If you have one you'd like to part with for a fair price... please email me at the below email address, or take out the NOSPAMPLEASE from the reply header above. I know some of you are laughing because of what the Maxcom really is inside, but I'd like to buy a used one anyway. Thanks for reading this post cheers, skipp skipp025 at yahoo.com Article: 97045 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA: COLLINS 270G-1, 302C-1, SM-2 +PARTS+MO Message-ID: <1JCYf.685540$qk4.262550@bgtnsc05-news.ops.worldnet.att.net> Date: Tue, 04 Apr 2006 22:48:29 GMT These Collins units are from my own station and can be seen at: http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy + Amp parts + 1 & 2 watt selected resistors + other stuff too. tnx, heytubeguy Article: 97046 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: Question about auto antenna cable and connectors Date: Tue, 04 Apr 2006 16:32:17 -0700 Message-ID: <12360g3fgj19iaf@corp.supernews.com> References: The coax used for every car radio of that vintage I ever saw (and I saw a lot) doesn't fit your description. It had a single, small diameter (#28 or so) wire rattling around loosely in a thin polyethylene tube, which was covered by a braided shield. The objective was to minimize the capacitance, but there obviously wasn't any control over Z0 or delay, since the small wire was free to move around inside the much larger diameter PE tube. There was no helically wound conductor. I think you might be looking in the wrong place for what you need. The connector fits your description, though. Roy Lewallen, W7EL Ronnie wrote: > Hi, > > This is not about ham radio, but rather a general question > about the type of cable and connectors that were found > between the antenna and the AM radio in GM cars in the > 60's. I'm trying to locate some technical information about > the cable and a source for the cable and connectors. > > I have an old airplane autopilot system that uses tuned circuit > to sense changes in the airplane's attitude and the position of > the control servos. Distributed variable inductances and > variable capacitors combine to establish the resonant > operating frequency of the system. The components are > connected together with specific lengths of cable and the > service manual points out that the lengths are critical because > of the added capacitance of the cable and connectors. > > The cable is marked as follows: > > "I. T. & T. Federal Cable R.E.C." > > It is a shielded cable with a spiral wound center conductor > that looks very much like the antenna cable I remember finding > in GM cars in the 60's. It also has the same type of connectors. > There is a center pin for the center conductor and a metal sleve > that extents back over the cable and makes a connection with the > shield and chassis of the radio. Friction holds the connector in > its mating socket - there are no threads, just a couple of splayed out > areas on the sleve. > > I was hoping one of you might be able to point me to a source > of technical information about this cable, such as the capacitance > per unit length, etc. The one piece I have measures about 10.5 pF / foot > or 415 pF / meter, but my measurements may not be all that accurate. > > Also, a source where the cable and connectors can be found today > would be appreciated. > > Thanks in advance for any help. > > Ronnie, N5CSE > > > Article: 97047 of rec.radio.amateur.homebrew Message-ID: <443309E7.D3413253@earthlink.net> From: "Michael A. Terrell" Subject: Re: Question about auto antenna cable and connectors References: Date: Wed, 05 Apr 2006 00:07:36 GMT Ronnie wrote: > > Hi, > > This is not about ham radio, but rather a general question > about the type of cable and connectors that were found > between the antenna and the AM radio in GM cars in the > 60's. I'm trying to locate some technical information about > the cable and a source for the cable and connectors. > > I have an old airplane autopilot system that uses tuned circuit > to sense changes in the airplane's attitude and the position of > the control servos. Distributed variable inductances and > variable capacitors combine to establish the resonant > operating frequency of the system. The components are > connected together with specific lengths of cable and the > service manual points out that the lengths are critical because > of the added capacitance of the cable and connectors. > > The cable is marked as follows: > > "I. T. & T. Federal Cable R.E.C." > > It is a shielded cable with a spiral wound center conductor > that looks very much like the antenna cable I remember finding > in GM cars in the 60's. It also has the same type of connectors. > There is a center pin for the center conductor and a metal sleve > that extents back over the cable and makes a connection with the > shield and chassis of the radio. Friction holds the connector in > its mating socket - there are no threads, just a couple of splayed out > areas on the sleve. > > I was hoping one of you might be able to point me to a source > of technical information about this cable, such as the capacitance > per unit length, etc. The one piece I have measures about 10.5 pF / foot > or 415 pF / meter, but my measurements may not be all that accurate. > > Also, a source where the cable and connectors can be found today > would be appreciated. > > Thanks in advance for any help. > > Ronnie, N5CSE It was RG62 93 ohm coax. The connectors were called "Motorola" plugs. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97048 of rec.radio.amateur.homebrew From: - exray - Subject: Re: Question about auto antenna cable and connectors Date: Tue, 04 Apr 2006 20:27:45 -0400 Message-ID: <12363o61bhj7g5e@corp.supernews.com> References: <443309E7.D3413253@earthlink.net> Michael A. Terrell wrote: > > > It was RG62 93 ohm coax. Certainly not in older radios. I don't know what they sell nowadays. I've seen that 'spiral' type of cable. They basically used the spiral as a means of maintaining the centre conductor in the average 'middle' of the hollow dielectric. The combined inductance and capacitance of the old cable was somewhat critical but the older radios provided an antenna trimmer to compensate for the variations. The electrical model was essentially a "voltage probe" and doesn't necessarily follow common antenna/feedline rules and thought. -Bill Article: 97049 of rec.radio.amateur.homebrew From: "Ronnie" References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: <5eGYf.62116$H71.61164@newssvr13.news.prodigy.com> Date: Wed, 05 Apr 2006 02:48:33 GMT Thanks Bill. The autopilot service manual I have shows a hand drawn figure of the cable that indicates a curly or spiral twist to the center conductor which appears as you stated to help keep the center conductor in the middle of the tube. It also mentions that the characteristics and length of the cable is part of the tuned circuit, but doesn't give any data on the cable. Like you, I'm sure I've seen that type of cable somewhere in the past and thought it was in an automotive antenna application, but it could have been elsewhere. Ronnie "- exray -" wrote in message news:12363o61bhj7g5e@corp.supernews.com... > Michael A. Terrell wrote: > > >> >> >> It was RG62 93 ohm coax. > > Certainly not in older radios. I don't know what they sell nowadays. > > I've seen that 'spiral' type of cable. They basically used the spiral as > a means of maintaining the centre conductor in the average 'middle' of the > hollow dielectric. > > The combined inductance and capacitance of the old cable was somewhat > critical but the older radios provided an antenna trimmer to compensate > for the variations. The electrical model was essentially a "voltage > probe" and doesn't necessarily follow common antenna/feedline rules and > thought. > > -Bill Article: 97050 of rec.radio.amateur.homebrew From: "Ronnie" References: <12360g3fgj19iaf@corp.supernews.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Date: Wed, 05 Apr 2006 02:48:33 GMT Thanks Roy. Now that you mention it, I do remember the straight center conductor inside the much larger diameter PE tube. The autopilot service manual I have shows a hand drawn figure of the cable that indicates a curly or spiral twist to the center conductor which appears to help keep the center conductor in the middle of the tube. I also mentions that the characteristics and length of the cable is part of the tuned circuit, but doesn't give any data on the cable. The connectors are like the connectors that were on the auto radios back then. I wonder where those could be found today. I can't seem to find them in any of the distributor catalogs I have. Maybe a trip to an automobile junk yard. Ronnie "Roy Lewallen" wrote in message news:12360g3fgj19iaf@corp.supernews.com... > The coax used for every car radio of that vintage I ever saw (and I saw a > lot) doesn't fit your description. It had a single, small diameter (#28 or > so) wire rattling around loosely in a thin polyethylene tube, which was > covered by a braided shield. The objective was to minimize the > capacitance, but there obviously wasn't any control over Z0 or delay, > since the small wire was free to move around inside the much larger > diameter PE tube. There was no helically wound conductor. I think you > might be looking in the wrong place for what you need. The connector fits > your description, though. > > Roy Lewallen, W7EL > > Ronnie wrote: >> Hi, >> >> This is not about ham radio, but rather a general question >> about the type of cable and connectors that were found >> between the antenna and the AM radio in GM cars in the >> 60's. I'm trying to locate some technical information about >> the cable and a source for the cable and connectors. >> >> I have an old airplane autopilot system that uses tuned circuit >> to sense changes in the airplane's attitude and the position of >> the control servos. Distributed variable inductances and >> variable capacitors combine to establish the resonant >> operating frequency of the system. The components are >> connected together with specific lengths of cable and the >> service manual points out that the lengths are critical because >> of the added capacitance of the cable and connectors. >> >> The cable is marked as follows: >> >> "I. T. & T. Federal Cable R.E.C." >> >> It is a shielded cable with a spiral wound center conductor >> that looks very much like the antenna cable I remember finding >> in GM cars in the 60's. It also has the same type of connectors. >> There is a center pin for the center conductor and a metal sleve >> that extents back over the cable and makes a connection with the >> shield and chassis of the radio. Friction holds the connector in >> its mating socket - there are no threads, just a couple of splayed out >> areas on the sleve. >> >> I was hoping one of you might be able to point me to a source >> of technical information about this cable, such as the capacitance >> per unit length, etc. The one piece I have measures about 10.5 pF / foot >> or 415 pF / meter, but my measurements may not be all that accurate. >> >> Also, a source where the cable and connectors can be found today >> would be appreciated. >> >> Thanks in advance for any help. >> >> Ronnie, N5CSE >> >> Article: 97051 of rec.radio.amateur.homebrew From: "James Thompson" Subject: home made pcb Date: Tue, 4 Apr 2006 22:58:44 -0400 Message-ID: <39212$44333267$438c83b0$32223@ALLTEL.NET> Just wanted to share this link for anyone that is thinking of making your own pcb's. This link is to the web site of tom gootee. It is a very well detailed step through on making pcb's using the toner transfer method, but not with the expensive toner transfer paper. I have tested this ( Jet PRINTPHOTO - Multi-project photo paper ) with much better results then I got with the high priced ttp. http://www.fullnet.com/u/tomg/gooteepc.htm Take a look, I was very impressed with the results.. JTT..kf4huf Article: 97052 of rec.radio.amateur.homebrew From: John Wilkinson Subject: filtering of LO signals Date: Wed, 5 Apr 2006 08:04:00 +0100 Message-ID: <1bl9r8lwo1ndy$.82388xlnw61j$.dlg@40tude.net> Hi, In my dual conversion receiver, I have a 45.455MHz second LO and a 45 - 75MHz first LO. First IF 45MHz second IF 455KHz Both these feed double balanced diode 7dBm mixers. Also I have not filtered these signals at all, and the first harmonic is roughly -20dBc - -30dBc. Is it imperitive that I filter these for my receiver to work? If so by how much? Best regards, John. Article: 97053 of rec.radio.amateur.homebrew From: "Jeff" Subject: Re: Question about auto antenna cable and connectors Date: Wed, 5 Apr 2006 12:32:51 +0100 Message-ID: References: <12360g3fgj19iaf@corp.supernews.com> <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Those connectors are still in use today in UK & Europe at least. A UK supplier is Maplin electronics. www.maplin.co.uk part no HHH12N Reagrds Jeff Article: 97054 of rec.radio.amateur.homebrew From: "Stargatesg1" References: <39212$44333267$438c83b0$32223@ALLTEL.NET> Subject: Re: home made pcb Message-ID: Date: Wed, 05 Apr 2006 11:39:08 GMT That is a very good, informative site! I have read it several times in the past few months and finally have tried it. It does work very well. -- RoD KD0XX PG-6-29404 "James Thompson" wrote in message news:39212$44333267$438c83b0$32223@ALLTEL.NET... > Just wanted to share this link for anyone that is thinking of making your > own pcb's. > This link is to the web site of tom gootee. It is a very well detailed step > through on making pcb's using the toner transfer method, but not with the > expensive toner transfer paper. I have tested this ( Jet PRINTPHOTO - > Multi-project photo paper ) with much better results then I got with the > high priced ttp. > http://www.fullnet.com/u/tomg/gooteepc.htm > Take a look, I was very impressed with the results.. JTT..kf4huf > > > Article: 97055 of rec.radio.amateur.homebrew From: "Ronnie" References: <12360g3fgj19iaf@corp.supernews.com> <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: Date: Wed, 05 Apr 2006 13:40:34 GMT Thanks for the lead. I see them on their web site. Ronnie "Jeff" wrote in message news:e109sn$jr0$1@emma.aioe.org... > Those connectors are still in use today in UK & Europe at least. A UK > supplier is Maplin electronics. > > www.maplin.co.uk part no HHH12N > > Reagrds > Jeff > Article: 97056 of rec.radio.amateur.homebrew From: "David G. Nagel" Subject: Re: Question about auto antenna cable and connectors Date: Wed, 05 Apr 2006 10:36:05 -0500 Message-ID: <1237p0ba92lo86c@corp.supernews.com> References: <12360g3fgj19iaf@corp.supernews.com> <5eGYf.62115$H71.16177@newssvr13.news.prodigy.com> Ronnie wrote: > Thanks for the lead. I see them on their web site. > Ronnie > > "Jeff" wrote in message news:e109sn$jr0$1@emma.aioe.org... > >>Those connectors are still in use today in UK & Europe at least. A UK >>supplier is Maplin electronics. >> >>www.maplin.co.uk part no HHH12N >> >>Reagrds >>Jeff >> > > > Jeff and Ronnie; That type of connector is known as a "Motorola Connector". Developed by Motorola for their automobile radios. Dave N Article: 97057 of rec.radio.amateur.homebrew From: Lawrence Statton N1GAK/XE1 Subject: Re: 20A 24v to 12v DC voltage dropper Date: 05 Apr 2006 09:12:46 -0700 Message-ID: <87hd58f1c1.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> References: <1144251776.987794.309360@i40g2000cwc.googlegroups.com> paul@burridge8333.fsbusiness.co.uk writes: > Hi all, > > Just bought this power supply and it turns out to be 24V as opposed to > 12 as I'd hoped. It's a heafty beast and should be good for running my > HF mobile if I can drop the voltage down to 13.8 whilst retaining about > 20 amps for the rig's TX current draw. I know I can buy a commercial > dropper, but that'd be cheating, so can anyone suggest how I might > acheive such a device through HB-ing? Which active devices would be > best for this purpose? I'd like over-voltage protection built-into any > design put forward if possible. Any pointers, please. > What you're saying is: You want to build a 20A 13.8V power supply with OVP. That it happens to take 24Vdc instead of 120Vac is trivial. Your options are -- design a nice switching converter (which based on the tenor of your question is beyond your mettle at the moment) or build an enormous linear regulator and dissipate a couple hundred watts making a very nice place for the cat to nap :) Best to set that 24V supply on the shelf, hope some day to find a good use for it, and either buy or build a 13.8V supply from scratch. > Thanks! > -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Lawrence Statton - lawrenabae@abaluon.abaom s/aba/c/g Computer software consists of only two components: ones and zeros, in roughly equal proportions. All that is required is to sort them into the correct order. Article: 97058 of rec.radio.amateur.homebrew From: Lawrence N1GAK/XE2 Subject: Re: 20A 24v to 12v DC voltage dropper Date: 05 Apr 2006 09:19:03 -0700 Message-ID: <8764lof11k.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> References: <1144251776.987794.309360@i40g2000cwc.googlegroups.com> <87hd58f1c1.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> Lawrence Statton N1GAK/XE1 writes: > What you're saying is: You want to build a 20A 13.8V power supply with > OVP. That it happens to take 24Vdc instead of 120Vac is trivial. Oops, just noticed the .co.uk in the OP - replace that 120 with a 240 :) 73 N1GAK -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Lawrence Statton - lawrenabae@abaluon.abaom s/aba/c/g Computer software consists of only two components: ones and zeros, in roughly equal proportions. All that is required is to sort them into the correct order. Article: 97059 of rec.radio.amateur.homebrew From: "RST Engineering" References: <1144251776.987794.309360@i40g2000cwc.googlegroups.com> Subject: Re: 20A 24v to 12v DC voltage dropper Date: Wed, 5 Apr 2006 10:11:22 -0700 Message-ID: Light aircraft switched over to 24 volt electrical systems sometime in the mid 1970s. You can sell that thing for a pretty penny to an avionics repair shop and get what you wanted in the first place. If there is a small civilian airport near you, inquire about where they get their radios fixed and take a trip to the one that seems most viable. Jim wrote in message news:1144251776.987794.309360@i40g2000cwc.googlegroups.com... > Hi all, > > Just bought this power supply and it turns out to be 24V as opposed to > 12 as I'd hoped. It's a heafty beast and should be good for running my > HF mobile if I can drop the voltage down to 13.8 whilst retaining about > 20 amps for the rig's TX current draw. I know I can buy a commercial > dropper, but that'd be cheating, so can anyone suggest how I might > acheive such a device through HB-ing? Which active devices would be > best for this purpose? I'd like over-voltage protection built-into any > design put forward if possible. Any pointers, please. > > Thanks! > Article: 97060 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: 20A 24v to 12v DC voltage dropper Date: Wed, 5 Apr 2006 13:02:20 -0500 Message-ID: References: <1144251776.987794.309360@i40g2000cwc.googlegroups.com> <87hd58f1c1.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> "Lawrence Statton N1GAK/XE1" wrote in message news:87hd58f1c1.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me... > paul@burridge8333.fsbusiness.co.uk writes: > > Hi all, > > > > Just bought this power supply ... 24V ...It's a heafty beast ... > > ... if I can drop the voltage down to 13.8 whilst retaining about > > 20 amps for the rig's TX current draw. ...Any pointers, please. > > > > What you're saying is: You want to build a 20A 13.8V power supply with > OVP. That it happens to take 24Vdc instead of 120Vac is trivial. > > Your options are -- design a nice switching converter (which based on > the tenor of your question is beyond your mettle at the moment) or > build an enormous linear regulator and dissipate a couple hundred > watts making a very nice place for the cat to nap :) Best to set that > 24V supply on the shelf, hope some day to find a good use for it, and > either buy or build a 13.8V supply from scratch. OR...OR...how about ... Unwind about half of the transformer secondary and fiddle with the regulator (appropriately). You should maintain the current level it originally had. The potential (sorry for the pun) for a fault causing a disastrous overvoltage is less as well. However be aware of the overhead voltage-- that is the difference in filter output voltage relative to 13.8, so you have enough room for the regulators, the ripple and mains dips. I did something like this with a 24V 5A supply long ago to get 5V 25A (5V. TTL logic was big then). I actually rewound the secondary with bigger wire to get the higher current capacity. ( also a slight tweek on the regulator topology for improved overhead). It had the common 723 regulator topology, so changing voltage was simply changing a zener and I must have beefed up the series pass transistors. Of course not knowing what your regulator topology is, this could be hard. I also have a 15 amp., Kepco, rack-mount linear hernia generator. Then, recently, a $99 MFJ 25 amp, hold-it-in-one-hand switcher. The ham fund had it and it took a lot less time than the re-wind. 73, Steve, K9DCI Article: 97061 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Question about auto antenna cable and connectors Date: Wed, 5 Apr 2006 13:13:54 -0500 Message-ID: References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <5eGYf.62116$H71.61164@newssvr13.news.prodigy.com> Nope. That's where. Autos. A piece of spiral plastic "rod" around the solid wire center conductor to space it in the center of the over-sized-hole dielectric. I thought it was also a "Motorola" connector, but didn't want to sound arrogant (still working at the circle M Ranch, you know). The AM receiver antenna was (is) nothing more that a capacitive probe hooked to the input, so the smaller the loading cap the better. Gee, if I shill have some around, perhaps some experimentation to determine the Z0 ... OK ... project 9,735, on the list for retirement. (yea, right) 73, Steve, K9DCI I only saw it referred to as low capacitance cable. Don't know if the Z0 was specified "Ronnie" wrote in message news:5eGYf.62116$H71.61164@newssvr13.news.prodigy.com... > Thanks Bill. > > The autopilot service manual I have shows a hand > drawn figure of the cable that indicates a curly or spiral twist > to the center conductor which appears as you stated to help > keep the center conductor in the middle of the tube. It also > mentions that the characteristics and length of the cable is part > of the tuned circuit, but doesn't give any data on the cable. > > Like you, I'm sure I've seen that type of cable somewhere in > the past and thought it was in an automotive antenna application, > but it could have been elsewhere. > > Ronnie > > "- exray -" wrote in message > news:12363o61bhj7g5e@corp.supernews.com... > > Michael A. Terrell wrote: > > > > > >> > >> > >> It was RG62 93 ohm coax. > > > > Certainly not in older radios. I don't know what they sell nowadays. > > > > I've seen that 'spiral' type of cable. They basically used the spiral as > > a means of maintaining the centre conductor in the average 'middle' of the > > hollow dielectric. > > > > The combined inductance and capacitance of the old cable was somewhat > > critical but the older radios provided an antenna trimmer to compensate > > for the variations. The electrical model was essentially a "voltage > > probe" and doesn't necessarily follow common antenna/feedline rules and > > thought. > > > > -Bill > > Article: 97062 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: Question about auto antenna cable and connectors Date: Wed, 05 Apr 2006 12:45:46 -0700 Message-ID: <12387jdrj3qgsd8@corp.supernews.com> References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> Michael A. Terrell wrote: > . . . > One of the engineers at Delco told me it was RG-62, and 93 ohms when > I was going to their annual car radio training back in the early '70s. > IBM also used RG-62 on their coaxial computer networking, but they used > BNC connectors. The automotive coax I'm familiar with isn't RG-62. Like automotive coax, RG-62 has a thin walled hollow insulating tube. But RG-62 has a polyethylene "string" which is helically wound around the center conductor to keep it centered in the hollow tube. The coax in every old automotive installation I've seen lacks this PE "string", so the center conductor is free to flop around inside the hollow tube. The effect of the "string" is to make RG-62's Z0 constant and predictable, and it will also increase the capacitance somewhat. Constant Z0 isn't important for the automotive application, and low capacitance is important. It seems to me the center conductor is smaller in the automotive coax than in RG-62, also. Roy Lewallen, W7EL Article: 97063 of rec.radio.amateur.homebrew From: "Ronnie" References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> Subject: Re: Question about auto antenna cable and connectors Message-ID: Date: Wed, 05 Apr 2006 20:57:14 GMT Roy is right. I looked up RG62 and this is not the cable I have. Here's what the autopilot service manual has to say about this cable. "The coaxial harness assembly CD-1, 2 and 3 is manufacued to specific lenghts and since the cable is a part of the tuned circuit, these lengths must not be altered. The sensor leads are made of very fine wires that are fed through a hollow insulator. Note that the fine wire has been coiled to provide flexibility and reduce the possibility of beaking and causing an open in the circuit." The diagram shows a hollow tube with a fine wire that is coiled running through it, a braid style shield over the hollow tube and an outer jacket over the braid. It seems to be a variant of the auto coax where the fine wire center conductor has been coiled instead of being left straight. Thanks for all the help with this, but don't worry yourselves about it. I have all the orginal pieces with connectors intact, but I was hoping to find the technical specs on the cable so I could understand the cable's impact on the resonant frequency. Ronnie "Roy Lewallen" wrote in message news:12387jdrj3qgsd8@corp.supernews.com... > Michael A. Terrell wrote: >> . . . >> One of the engineers at Delco told me it was RG-62, and 93 ohms when >> I was going to their annual car radio training back in the early '70s. >> IBM also used RG-62 on their coaxial computer networking, but they used >> BNC connectors. > > The automotive coax I'm familiar with isn't RG-62. > > Like automotive coax, RG-62 has a thin walled hollow insulating tube. But > RG-62 has a polyethylene "string" which is helically wound around the > center conductor to keep it centered in the hollow tube. The coax in every > old automotive installation I've seen lacks this PE "string", so the > center conductor is free to flop around inside the hollow tube. The effect > of the "string" is to make RG-62's Z0 constant and predictable, and it > will also increase the capacitance somewhat. Constant Z0 isn't important > for the automotive application, and low capacitance is important. > > It seems to me the center conductor is smaller in the automotive coax than > in RG-62, also. > > Roy Lewallen, W7EL Article: 97064 of rec.radio.amateur.homebrew Message-ID: <44343447.3080508@nowhere.com> From: Leif Holmgren Subject: Re: 20A 24v to 12v DC voltage dropper References: <1144251776.987794.309360@i40g2000cwc.googlegroups.com> <1144254585.496785.306960@i39g2000cwa.googlegroups.com> Date: Wed, 05 Apr 2006 23:19:03 +0200 mrhaney wrote: > Sell the 24 VDC power supply,Boatanchor people still use 24V supplies.. I feel offended. I have a pretty new 100W+ 432MHz amp that runs on 24V and a even newer 100W+ 1296MHz amp that runs on 34V! Article: 97065 of rec.radio.amateur.homebrew Subject: ** FLEA at MIT ** Sunday April 16th Cambridge MA From: w1gsl@mit.edu (Steven L. Finberg) Date: 06 Apr 2006 03:00:28 GMT Message-ID: <4434844c$0$560$b45e6eb0@senator-bedfellow.mit.edu> The Seasons First.... +++ Now even more Buyers Parking !!! Thanks to TKT we have use of their new parking lot across Albany St from the SWAPFEST !!! !! ** More Buyers PARKING is available ** for details see http://web.mit.edu/w1gsl/Public/flyer *** !!!! In our Traditional GARAGE and the adjacent lot !!!! **** so come rain or shine or super heat the Flea is on !!! ********* $1 buyers discount with hardcopy of this notice ******** COMPUTERS - ELECTRONICS - HAM RADIO - COMPUTERS - ELECTRONICS - HAM RADIO FLEA all SUMMER at MIT Sunday April 16th 2006 9AM-2PM Come to the city for a great flea - plenty of free parking. MIT's electronics and ham radio flea will take place on the third Sunday of each month this summer, April thru October. There is tailgate space for over 600 sellers and free, off-street parking for >2000 cars! Buyers admission is $5 (you get $1 off if you're lucky enough to have a copy of our ad) and sellers spaces are $20 for the first and $15 for each additional at the gate. The flea will be held at the corner of Albany and Main streets in Cambridge; right in the Kendall Square area from 9AM to 2PM, with sellers set-up time starting at 7AM. SEASON PASS + Advance Seller Discount A sellers discount season pass is available which offers a 30% discount. By prepaying you get a discount and earlier admission. See the registration form. *** Attention Sellers *** Prepaid vendors.. Season Pass or monthly, will be admitted FIRST. Separate lines will form prior to gate opening for prepaid and nonprepaid vendors !! RAIN or SHINE !! Have no fear of rain, a covered well illuminated tailgate area is available for all sellers (6'8" clearance). Talk-in: 145.23- (PL 88.5) W1BOS/R and W1XM/R-449.725/444.725 (PL 114.8/2A). Sponsors: MIT Electronics Research Society MIT UHF Repeater Association (W1XM) MIT Radio Society (W1MX) Harvard Wireless Club (W1AF) For more info / advanced reservations 617 253 3776 ********** $1 buyers discount with hard copy of this notice ************ <<<<<<<<<<<<<<<<<<<<<<<< cut here >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mail the coupon below by the 5th of the month to be a Prepaid Vendor. FLEA at MIT 2006 Rates SELLERS To use your prepaid spaces the named vendor MUST be present. Rates include one admission per space. Season Pass $99 First Space includes all 7 2006 meets $70 each additional Space Must be received by April 16th Advance $17 First space $12 Additional Spaces Must be received by the 5th of the month. Gate Admission $20 First Space $15 Additional Spaces Admission is after the prepaid vendors Early Bird Buyer -Admission after the prepaid vendor line is admitted. ~ 7:15AM ** You may not sell. ** $15 per person at the gate. ****************************** cut here ******************************* FLEA at MIT 2006 Advance Space Application ____April ____May ____June ____ July ____Aug ___Sept ____Oct @ $17 for the first each month + $12 each additional ____ Season Pass @$99 _____ Additional Season Spaces @$70 Name ________________________ Call __________ $ Included______ Address ________________________ Phone __________ Make Check to The MIT Radio Society City ____________________ State _______ Zip _______ PO Box 397082 Cambridge MA 02139 E-mail _____________________________________________ ******************************************************************************* Steve Finberg W1GSL w1gsl@mit.edu PO Box 82 MIT Br Cambridge MA 02139-7082 617 258 3754 ******************************************************************************* Article: 97066 of rec.radio.amateur.homebrew Message-ID: <44348C60.D9909E41@earthlink.net> From: "Michael A. Terrell" Subject: Re: Question about auto antenna cable and connectors References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> Date: Thu, 06 Apr 2006 03:35:28 GMT Roy Lewallen wrote: > > Michael A. Terrell wrote: > > . . . > > One of the engineers at Delco told me it was RG-62, and 93 ohms when > > I was going to their annual car radio training back in the early '70s. > > IBM also used RG-62 on their coaxial computer networking, but they used > > BNC connectors. > > The automotive coax I'm familiar with isn't RG-62. > > Like automotive coax, RG-62 has a thin walled hollow insulating tube. > But RG-62 has a polyethylene "string" which is helically wound around > the center conductor to keep it centered in the hollow tube. The coax in > every old automotive installation I've seen lacks this PE "string", so > the center conductor is free to flop around inside the hollow tube. The > effect of the "string" is to make RG-62's Z0 constant and predictable, > and it will also increase the capacitance somewhat. Constant Z0 isn't > important for the automotive application, and low capacitance is important. > > It seems to me the center conductor is smaller in the automotive coax > than in RG-62, also. > > Roy Lewallen, W7EL I saw both types on car radio antennas, and some was clearly marked RG-62. Both types meet the original RG62 specification, they just use two different methods to minimize dielectric losses, like fused disk hardline used in CATV and other applications that require low loss cabling. Also, why would one of the Delco engineers who designed their car radios lie about the coax they used? He was explaining the then brand new AM/FM/8-track combo when I asked a number of questions about the RF front end. As usual, you will continue to believe whatever you want to. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97067 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: Question about auto antenna cable and connectors Date: Wed, 05 Apr 2006 23:50:15 -0700 Message-ID: <1239ehalkdecf1c@corp.supernews.com> References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> <44348C60.D9909E41@earthlink.net> Michael A. Terrell wrote: > > I saw both types on car radio antennas, and some was clearly marked > RG-62. Both types meet the original RG62 specification, they just use > two different methods to minimize dielectric losses, like fused disk > hardline used in CATV and other applications that require low loss > cabling. Also, why would one of the Delco engineers who designed their > car radios lie about the coax they used? He was explaining the then > brand new AM/FM/8-track combo when I asked a number of questions about > the RF front end. As usual, you will continue to believe whatever you > want to. I happened to find a piece of the automotive cable -- complete with connector -- in my junk box, which I'm pretty sure was cut from a replacement antenna probably purchased in the '70s. This particular cable lacks the PE "string", but the ~#31 center conductor is crimped in a sort of zig-zag shape to keep it in place in the hollow tube. The aviation cable apparently has the center conductor bent into a (presumably loose) helix for the same purpose. I've never seen RG-62 cable without the PE "string", but don't have any trouble believing that someone might manufacture it without the "string". I also don't have trouble believing that some auto manufacturers might use RG-62. Although I saw a lot of auto installations in the '60s, when I moonlighted repairing such things, I never saw RG-62. But I certainly didn't see anywhere near every possibility, and I could have missed seeing a marking. Roy Lewallen, W7EL Article: 97068 of rec.radio.amateur.homebrew From: Alan Peake Subject: Re: Chebyshev low-pass / Amp questions / Etc. Date: Thu, 06 Apr 2006 17:13:33 +1000 Message-ID: <4434BF9D.7030404@killspam.internode.on.net> References: <1144285527.509158.72800@e56g2000cwe.googlegroups.com> > However, when I drove it on 14Mhz, the SWR was good when I drove it > with 10 watts or below, but when the drive power goes up, so does the > SWR. If the amplifier is distorting, you may be getting 2nd or 3rd harmonics of the 14MHz. Perhaps the output impedance of the amplifier is not 50 ohms at the harmonic frequencies and so you will see increased VSWR. I don't know what the topology of your amplifier is but if it's push-pull like many solid-state amps, then it's probable that the harmonics are third order. Alan VK2ADB Article: 97069 of rec.radio.amateur.homebrew From: Paul Keinanen Subject: Re: Chebyshev low-pass / Amp questions / Etc. Message-ID: <3bi932l6b35bdg6otpfapg63do4kckpsi0@4ax.com> References: <1144285527.509158.72800@e56g2000cwe.googlegroups.com> Date: Thu, 06 Apr 2006 11:07:46 +0300 On 5 Apr 2006 18:05:27 -0700, KC2PIH@gmail.com wrote: > >However, when I drove it on 14Mhz, the SWR was good when I drove it >with 10 watts or below, but when the drive power goes up, so does the >SWR. > >Any ideas on what is causing that? Assuming your SWR instrument is reliable at 10 W (which you should test with a reliable, say 100 ohm dummy load), an other suggestion is that there are some flashovers in some reactive components. Is any capacitor or inductor getting hot after a long test ? Paul OH3LWR Article: 97070 of rec.radio.amateur.homebrew From: "Paul VK3DIP" References: <1142687392.568430.122110@e56g2000cwe.googlegroups.com> <7SLXf.22113$dy4.15868@news-server.bigpond.net.au> <1144071661.354064.32740@z34g2000cwc.googlegroups.com> Subject: Re: Return Loss Bridge Accuracy Questions Message-ID: Date: Thu, 06 Apr 2006 12:19:52 GMT Steve, Yes the connectors can make all the difference, as you would have seen >from the write-up I used BNC's and even though they were reasonably good quality at the extremes just wiggling the connectors slightly to vary the contact resistance ( and probably capacitance etc.) a bit can make dB's of difference to the measured directivity. Thankfully this is not a big problem under normal usage. Your PL259's would probably have similar effects though possibly not quite as noticeable at the directivities and frequencies you were looking at. Paul. VK3DIP Article: 97071 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <1143049636.448285.24980@j33g2000cwa.googlegroups.com> <1143321832.545680.142220@g10g2000cwb.googlegroups.com> <1143385239.766015.160760@i39g2000cwa.googlegroups.com> <8h3h22582psr78h3n6iq7q3thdgr628c1d@4ax.com> Subject: Re: Eddystone dial and custom dial plates Message-ID: Date: Thu, 06 Apr 2006 12:44:39 GMT "Ted" wrote in message news:u9v432dso5qnjt426519a5mfln1090htk4@4ax.com... > On Mon, 03 Apr 2006 01:37:23 GMT, "Dale Parfitt" > wrote: > > >>Hi Ted, >>I quickly looked at the VFO schematic in my1994 Handbook that had the PR. >>I >>seem to recall in the end I replaced C1 with a short- just eliminating it. >>Not 100% positive, but think that was what it came down to in order to >>get >>good linearity out of my VFO. >> >>Dale >> > Dale, > I'll check that out. My value for C3 from the spreadsheet came out to > be 319.1 vs the 127.02 in the magazine. I used the spreadsheet on the > example on page 4.4 of EMRFd and it worked out ok. In the QST > example, setting C1 to a very low value actually increases the > discrepancy with C3, though. More mystery! > > Tnx, > Ted KX4OM Hi Ted, No doubt, the VFO could be put on the correct freq range with C3 included- it was just very nonlinear. Dale Article: 97072 of rec.radio.amateur.homebrew From: mcalhoun@ksu.edu Subject: How get RF through a sealed window? Date: 6 Apr 2006 11:06:22 -0500 Message-ID: I gave a presentation on "How Ham Radio Can Help You in an Emergency" to 70 Emergency Management types last week, and the windows in the building which hosted the meeting were NOT open-able (so I "made do" with an inside VHF antenna and didn't even try to demonstrate HF). But in emergency/expedient situations, it would be really handy if one could pass at HF, say, 100 watts of RF energy through a window (I visualize some foil strips and an inductor or two to "tune out" the capacitance) to an external antenna. I've been told that the April, 1989, issue of Ham Radio magazine carried an article "Easy antenna access for urban apartment dwellers" (for 15 meters) by Bryan Bergeron, NU1N, starting on page 18. I'd sure like to read that article; can anyone send me a copy? -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 97073 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Chebyshev low-pass / Amp questions / Etc. Date: Thu, 6 Apr 2006 10:41:21 -0500 Message-ID: References: <1144285527.509158.72800@e56g2000cwe.googlegroups.com> wrote in message news:1144285527.509158.72800@e56g2000cwe.googlegroups.com... > Hello - I've got my hands on an HF amp and I just don't know about the > quality of the low-pass filter in it. It appears to have a 5-element > Chebyshev low pass filter in it. You don't say if this is on the input or output of said amp - based on your question the assumption is input. Why do you say Chebyshev if you don't know values? I don't have anyway to measure the > values of the inductors or capacitors used in that circuit. When I > drive it above 25Mhz (into a dummy load of course), the SWR is low. How low, (give numbers) and what ate you measuring it with? It > has four MRF-454 transitors in it and when I drive it with 25-30 watts, > I see 400+ watts out PEP. The SSB audio sounds clear too, so without > understanding the circuitry fully, it seems to be biased "above" class > C. This may or may not be any indication of linearity. A better check would be to listen off channel. > > However, when I drove it on 14Mhz, the SWR was good when I drove it > with 10 watts or below, but when the drive power goes up, so does the > SWR. ... Thanks! > Scott McClements Again, how far "UP" give numbers. 73, Steve, K9DCI Article: 97074 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: making a uhf bandpass filter using semi rigid or hardline? Date: Thu, 6 Apr 2006 11:12:27 -0500 Message-ID: References: <1144259278.805899.268620@z34g2000cwc.googlegroups.com> Depending on the type of ceramic filter, some can be moved either up or down (yep, down) in frequency with a dremel and diamond wheel. I have done this when designing AMPS transceivers for a different frequency range (lower) when the lead time on sample filters from Murata in a different range was too long. Moving them relatively small amounts, the bandwidth stays quite close. I think I went down something like 15-20 MHz. Moving them as far as you want far may be (probably is) a stretch You are trying to go from the cellular base receive to the ham band. Depending on what the amp is between the filter and output, the amp may need some tweeking for this difference in frequency. IF you had some mobile receive (45 MHz higher) filters, going that far would be easier, but I'm sure you don't. A Comb-line ceramic filter is a block that has holes in it. It is like a box with 1/4 wave rods in a line except the box is filled with ceramic. It is about 1/4 inch thick, maybe 1/2 inch 'high' and long enough for as many hole-resonators as it has in a line. Each hole is plated inside and is a "shortened quarter wave transmission line" resonator. The "ground" or "shield" equivalent of the transmission line resonators is the two plated sides of the block. It is filed with a high-K dielectric having a very good temperature characteristics and therefore the 1/4 wave is very short -- the virtue of these filters. Ours typically had three poles (holes-resonators) for the receive and 5 for the exciter filter. One end (the 'bottom' or the shorted end of the quarter wave resonators) is all metal plating and holes in a line. The opposite end (the resonator open end) has little or no plating and may even show the effects of grinding to tune it. However, some are constructed with this end mounted down and therefore covered by the mounting bracket which will probably be soldered or glued on and allow limited access. Coupling for the desired bandwidth and ripple is achieved by the spacing of the resonator-holes in the solid high-k ceramic dielectric therefore, you can't buck about with coupling and must take what you get after moving. To move up, you remove resonator from the "open" end, shortening it. To move down, you remove small areas of the ground plating at the base of the resonator-holes. I used the Dishall method and they came right on. If the filters are comb-line with top coupling for input and output, moving them *up* far (by shortening the resonator -- which *is* the hole), I think will be hard because you will loose coupling between resonator and coupling tab when you shorten the resonator...however you could regain coupling by attaching a wire to the coupling tab and run it down the hole (the "correct" amount) to proper get coupling back. 73, Steve K9DCI wrote in message news:1144259278.805899.268620@z34g2000cwc.googlegroups.com... > Im trying to build a preamp for the 902-928 band, I bought several > surplus cellular preamps > in a auction, these had 824-855mhz ceramic filters. I took the filter > out and the noise floor > took off, i need to replace the bandpass with one in the 902-928 mhz > range. I have some > semi rigid coax .080 and of various sizes of small hardline .250 - > .540. In the past ive seem articles on making preamps & filters using > semi rigid coax but cant find any now that im ready to start building a > ATV receiver. > Article: 97075 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: How get RF through a sealed window? Date: Thu, 6 Apr 2006 10:59:36 -0700 Message-ID: <123alpjhjjbva3@corp.supernews.com> References: wrote in message news:e13e9u$q3u@unix1.cc.ksu.edu... > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. In an emergency I'd say... uh... just leave the window open? :-) Over on eHam.net there's a recent article on building yourself a simple rectangular wooden panel to stick in the frame of an (open) window. You then just drive holes in the panel as needed to run cables, etc. I've even seen people who didn't have, e.g., a drill or jigsaw do the same thing using a thick-ish chunk of stiff foam (insulation material or even presentation poster board) and an X-acto knife. Article: 97076 of rec.radio.amateur.homebrew From: Lawrence Statton N1GAK/XE1 Subject: Re: How get RF through a sealed window? Date: 06 Apr 2006 11:30:13 -0700 Message-ID: <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> References: <123alpjhjjbva3@corp.supernews.com> "Joel Kolstad" writes: > wrote in message news:e13e9u$q3u@unix1.cc.ksu.edu... > > But in emergency/expedient situations, it would be really handy if one > > could pass at HF, say, 100 watts of RF energy through a window (I > > visualize some foil strips and an inductor or two to "tune out" the > > capacitance) to an external antenna. > > In an emergency I'd say... uh... just leave the window open? :-) But be sure to bring a hefty brick along to create the opening in the first place :) The OP's dilema was that the window COULD NOT open, and therefore some way to pass RF through glass would have been Useful. -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Lawrence Statton - lawrenabae@abaluon.abaom s/aba/c/g Computer software consists of only two components: ones and zeros, in roughly equal proportions. All that is required is to sort them into the correct order. Article: 97077 of rec.radio.amateur.homebrew From: "Cecil Moore" References: Subject: Re: How get RF through a sealed window? Message-ID: Date: Thu, 06 Apr 2006 18:44:48 GMT wrote: > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. What I have done is plan ahead by drilling two small holes in the glass and plugging them with nylon screws when not in use. That works best on the first floor. :-) -- 73, Cecil, W5DXP Article: 97078 of rec.radio.amateur.homebrew From: "Brian Murrey" References: Subject: Re: How get RF through a sealed window? Message-ID: Date: Thu, 06 Apr 2006 18:46:02 GMT You'd have better luck with HF than VHF or UHF making it through any solid object. I have used a homebrew mag loop in a hotel room on several ocassions with some luck..on 20 and 40. I have a 40m dipole in my attic, and I runn less than 5w HF most of the time and I have WAS on several ocassions, I try to WAS every year. 73 -- ========================================= Radio Amateurs - Fill your junk box, from my junkbox! http://www.hamradparts.com 73 de KB9BVN ========================================= wrote in message news:e13e9u$q3u@unix1.cc.ksu.edu... > I gave a presentation on "How Ham Radio Can Help You in an Emergency" > to 70 Emergency Management types last week, and the windows in the > building which hosted the meeting were NOT open-able (so I "made do" > with an inside VHF antenna and didn't even try to demonstrate HF). > > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. > > I've been told that the April, 1989, issue of Ham Radio magazine carried > an article "Easy antenna access for urban apartment dwellers" (for 15 > meters) by Bryan Bergeron, NU1N, starting on page 18. > > I'd sure like to read that article; can anyone send me a copy? > -- > --Myron A. Calhoun. > Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge > PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 > NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 97079 of rec.radio.amateur.homebrew From: dplatt@radagast.org (Dave Platt) Subject: Re: How get RF through a sealed window? Date: Thu, 06 Apr 2006 19:05:48 -0000 Message-ID: <123apkcflafh49@corp.supernews.com> References: <123alpjhjjbva3@corp.supernews.com> <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> In article <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me>, Lawrence Statton N1GAK/XE1 wrote: >But be sure to bring a hefty brick along to create the opening in the first >place :) > >The OP's dilema was that the window COULD NOT open, and therefore some >way to pass RF through glass would have been Useful. A lot of modern buildings have glass windows which not only cannot be opened, but which have a "low-E" (low thermal emission) coating on the glass. This is (I believe) a very thin layer of vapor-deposited metal. Its RF attenuation is considerable. Some years ago, we had our house windows (1960s-era glass) replaced with new ones using a low-E-coated glass. A previously-workable signal path for 802.11 signals, which got to the back of the house from an access point in the garage by going through the garage door and a couple of exterior windows, suddently became quite unusable - I had to install an additional access point to cover that part of the house. The more obviously shaded or reflective the glass, the more of a problem for RF transmission or coupling this stuff is likely to present. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 97080 of rec.radio.amateur.homebrew From: dplatt@radagast.org (Dave Platt) Subject: Re: icom ic-t2h tx expand diode 18 removal mods and findings Date: Thu, 06 Apr 2006 19:32:19 -0000 Message-ID: <123ar638jtmse50@corp.supernews.com> References: <1144313197.648935.326340@i40g2000cwc.googlegroups.com> In article <1144313197.648935.326340@i40g2000cwc.googlegroups.com>, wrote: >after doing the remove diode 18 on my icom ic-t2h to expand tx i >noticed that my reception in the higher (170mhz and above) was >distorted. i also noticed a marked reduction in transmitting power in >the high frequencies, stations i could reach at 140.20 couldn't be >reached at 172.15, they couldn't reach me either at 172.15 though we >easily could reach each other at 140.20 > >the low (140-148mhz) seemed to work ok. > >i am studying the electrical diagram if i also have to remove the other > >diode to improve higher VHF freek reception. > > >what you guys find out so far? The fact that you can persuade the radio's synthesizer to tune frequencies outside of the 2-meter band, does not mean that either the transmitter or receiver circuitry is necessarily going to work well on those frequencies. The transmitter circuit is very probably "tuned" for operation in the 2-meter band, and forcing it to operate outside of its tuning range will probably result in degraded performance. The radio almost certainly has a low-pass filter between the RF module and the antenna. This is necessary in order to keep the radio's transmitter from emitting spurs or harmonics in excess of the FCC limits. This filter is likely to "roll off" any transmissions above the 2-meter band to some extent, and (if it's in the receive pathway) will probably reduce the received signal strength as well. It's even possible that transmitted at such a high frequency might damage the radio's power amplifier... the amp's likely to be looking into a severe impedance mismatch and the high SWR might overstress it. You don't say where you live, but you should be aware that here in the U.S. it's illegal to transmit outside of the 2-meter band with a radio modified in this fashion. Google for "Jack Gerritsen" to understand some of the potential consequences. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 97081 of rec.radio.amateur.homebrew From: mcalhoun@ksu.edu Subject: Re: How get RF through a sealed window? Date: 6 Apr 2006 15:07:17 -0500 Message-ID: References: <123alpjhjjbva3@corp.supernews.com> >> But in emergency/expedient situations, it would be really handy if one >> could pass at HF, say, 100 watts of RF energy through a window .... >Over on eHam.net there's a recent article on building yourself a simple >rectangular wooden panel to stick in the frame of an (open) window. You then >just drive holes in the panel as needed to run cables, etc.... I can just see me now: * Drive to the High-n-Mighty Hotel where I'm to provide communications for the Red Cross (or Salvation Army) shelter * Ask the desk clerk for someone to help me carry my sledgehammer and other stuff in my grab-n-go kit to the shelter * Walk into shelter where x-hundred shelterees are fast asleep * Take sledgehammer and bash a hole through a window * .... Nope, that's just not gonna work! -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 97082 of rec.radio.amateur.homebrew From: mcalhoun@ksu.edu Subject: Re: How get RF through a sealed window? Date: 6 Apr 2006 15:13:53 -0500 Message-ID: References: >You'd have better luck with HF than VHF or UHF making it through any solid >object. I have used a homebrew mag loop in a hotel room on several >ocassions with some luck..on 20 and 40. Even in an emergency situation, I just don't think it would be a good idea to string some kind of an antenna above the heads of shelterees and then start soaking them with RF, especially depending on the HF frequency in use. In fact, I suspect the FCC's RF-exposure regulations would frown on one doing so! -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 97083 of rec.radio.amateur.homebrew Message-ID: <4435804C.B3342CE2@earthlink.net> From: "Michael A. Terrell" Subject: Re: Question about auto antenna cable and connectors References: <443309E7.D3413253@earthlink.net> <12363o61bhj7g5e@corp.supernews.com> <44340C37.B9A3788D@earthlink.net> <12387jdrj3qgsd8@corp.supernews.com> <44348C60.D9909E41@earthlink.net> <1239ehalkdecf1c@corp.supernews.com> Date: Thu, 06 Apr 2006 20:56:34 GMT Roy Lewallen wrote: > > Michael A. Terrell wrote: > > > > I saw both types on car radio antennas, and some was clearly marked > > RG-62. Both types meet the original RG62 specification, they just use > > two different methods to minimize dielectric losses, like fused disk > > hardline used in CATV and other applications that require low loss > > cabling. Also, why would one of the Delco engineers who designed their > > car radios lie about the coax they used? He was explaining the then > > brand new AM/FM/8-track combo when I asked a number of questions about > > the RF front end. As usual, you will continue to believe whatever you > > want to. > > I happened to find a piece of the automotive cable -- complete with > connector -- in my junk box, which I'm pretty sure was cut from a > replacement antenna probably purchased in the '70s. This particular > cable lacks the PE "string", but the ~#31 center conductor is crimped in > a sort of zig-zag shape to keep it in place in the hollow tube. The > aviation cable apparently has the center conductor bent into a > (presumably loose) helix for the same purpose. I've never seen RG-62 > cable without the PE "string", but don't have any trouble believing that > someone might manufacture it without the "string". I also don't have > trouble believing that some auto manufacturers might use RG-62. Although > I saw a lot of auto installations in the '60s, when I moonlighted > repairing such things, I never saw RG-62. But I certainly didn't see > anywhere near every possibility, and I could have missed seeing a marking. > > Roy Lewallen, W7EL Some of the third party replacement antennas were made with military surplus RG62, and had hand soldered motorola plugs instead of the OEM crimped plugs. I cut up a lot of old antenna cables and stripped the copper braid to use as solder wick by dipping it into liquid rosin. Some had the plastic spacer for the center conductor, but most didn't. Some weeks we replaced a half dozen car radio antennas, so I always had plenty of copper braid at hand. years later I worked for a CATV company repairing converters. The braid from the control cables was a little under 1/8" when it was pulled tight and flattened by pulling it around the blade of a screwdriver. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97084 of rec.radio.amateur.homebrew From: Bob Liesenfeld Subject: OT: Brain pick Date: Thu, 06 Apr 2006 16:01:53 -0500 Message-ID: <443581C1.328877BE@visi.com> Hi gang, I know there are a number of people on this list who work in 2 way and other RF fields. I used to, but have been out of the loop for a while so I need your current expertise. Specifically, I need to determine what transmitting type services currently (or may soon) use amplitude modulation of the radiated signal in the 80MHz to 1GHz range. In my day it was restricted to aircraft comms in the 108MHz to 138MHz range and the video carrier of broadcast TV. Is this still the case, or have things changed? I don't need to know about 'closed circuit' paths such as cable TV and the like, only services that radiate RF. Also, if anyone has any knowledge of the general picture of frequency allocations in the same range quoted above in Europe and Asia, I would appreciate it. Thanks a lot and please respond off list. Bob WB0POQ wb0poq@visi.com Article: 97085 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: How get RF through a sealed window? Date: Thu, 6 Apr 2006 14:49:11 -0700 Message-ID: <123b38gspg7kg65@corp.supernews.com> References: <123alpjhjjbva3@corp.supernews.com> <87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me> "Lawrence Statton N1GAK/XE1" wrote in message news:87y7yieeve.fsf@hummer.i-did-not-set--mail-host-address--so-shoot-me... > The OP's dilema was that the window COULD NOT open, and therefore some > way to pass RF through glass would have been Useful. Oops, sorry I missed that! Article: 97086 of rec.radio.amateur.homebrew From: "James Thompson" References: <1144344552.349256.25410@e56g2000cwe.googlegroups.com> Subject: Re: Radio-Electronics Sept 89 Date: Fri, 7 Apr 2006 00:12:57 -0400 Message-ID: <23eaa$4435e6ca$438c8615$2065@ALLTEL.NET> wrote in message news:1144344552.349256.25410@e56g2000cwe.googlegroups.com... > Hi All, > > I am looking for a spectrum monitor article, part 1 which appears in RE > Sept 89. > If you have the issues, would like to get a copy of this article, > either scanned or otherwise. > > de KJ4UO > I just went through a stack of old mags and that sounds familier. I will check tomorrow and get back to you on that. JTT kf4huf.. Article: 97087 of rec.radio.amateur.homebrew Subject: Re: How get RF through a sealed window? From: "Allan R. Batteiger" References: Message-ID: Date: Fri, 07 Apr 2006 05:45:28 GMT mcalhoun@ksu.edu wrote in news:e13e9u$q3u@unix1.cc.ksu.edu: > I gave a presentation on "How Ham Radio Can Help You in an Emergency" > to 70 Emergency Management types last week, and the windows in the > building which hosted the meeting were NOT open-able (so I "made do" > with an inside VHF antenna and didn't even try to demonstrate HF). > > But in emergency/expedient situations, it would be really handy if one > could pass at HF, say, 100 watts of RF energy through a window (I > visualize some foil strips and an inductor or two to "tune out" the > capacitance) to an external antenna. > > I've been told that the April, 1989, issue of Ham Radio magazine carried > an article "Easy antenna access for urban apartment dwellers" (for 15 > meters) by Bryan Bergeron, NU1N, starting on page 18. > > I'd sure like to read that article; can anyone send me a copy? I do not have the article but one solution that was proposed and tried worked great. Use tinfoin and rubber glue, cut the tin foil to fit the glass. Apply rubber glue to hold the foil to each side of the glass, Thickness of teh glass is not important. In my case I used the metal frame of the glass to carry the gound signal through the window frame. I then used an antenna tuner to adjust out the capacitor I just created. Worked great, no drilling no running coax in and out so I can close the window etc. Allan WB5QNG Article: 97088 of rec.radio.amateur.homebrew From: Allison-nospam@nouce.bellatlantic.net Subject: Re: filtering of LO signals Message-ID: References: <1bl9r8lwo1ndy$.82388xlnw61j$.dlg@40tude.net> <1144241239.572370.217140@g10g2000cwb.googlegroups.com> Date: Fri, 07 Apr 2006 12:04:19 GMT I have gotten similar results using level-7 DBMs. So I tried it with simple balanced mixers such as CA3028, NE602 and confirmed that a clean LO is desireable using any mixer. Allison Fri, 7 Apr 2006 00:51:30 -0500, "Pete KE9OA" wrote: >I have been characterizing some of the new Mini-Circuits LAVI-XXX series >mixers. These devices have an IP3 in the +35 to +40dBm range. Using HP 8644 >signal generators to characterize IP3, I was only able to achieve >+33dBm.......IP2 was only in the low 60s. Return loss at the RF and I.F. >ports was only measured at 12 to 13dB. >I spoke to Mr. Lu Chen at Mini-Circuits and he explained that all sources >must have all harmonics down by at least -65dBc, and that the 6th and 9th >harmonics of the LO can be especially troublesome in degrading the >performance. >Using a low-pass filter on the LO improved the return loss to 20dB, while >the IP2 improved to +72dBm and the IP3 improved to +40dBm. It is always good >to have a clean LO source. If your 2nd harmonic is below -25dBc and higher >order terms are below -40dBc, you will have pretty good performance from the >receiver. A low-pass filter ahead of the 1st mixer will help reject that 90 >to 120MHz image band. > >Pete > >"MadEngineer" wrote in message >news:1144241239.572370.217140@g10g2000cwb.googlegroups.com... >> Hi John, >> >> If by 'first harmonic' you actually mean the second harmonic of your LO >> (the 'first harmonic' usually refers to the fundamental frequency), the >> answer depends a lot on how well your input is filtered, and on what >> you have after the mixers. >> >> This sounds like a 0-30Mhz shortwave receiver. If your input does not >> have a good low pass filter for example, you may find strong FM signals >> getting into the first IF passband as a result of the 2nd LO harmonic. >> Note that your mixer inherently responds at odd harmonics of the LO >> (3rd,5th...) and filtering odd harmonics out at the LO port does >> little, so a good low pass filter is necessary anyway. >> The second mixer is probably not as critical. Others will probably add >> some more information. >> >> Regards, >> Glenn AC7ZN >> > Article: 97089 of rec.radio.amateur.homebrew From: "Brian Murrey" References: Subject: Re: How get RF through a sealed window? Message-ID: Date: Fri, 07 Apr 2006 12:40:12 GMT Perhaps. In an emergency situation though, you do what you need to do and try not to let the regulations keep you from saving lives and/or property..while still keeping the regs in mind. When I use my portable mag loop for 20 and 40, from my hotel room, I try to place it outside my room...but that hasn't always been possible. At my low power I would have to guess the RF I'm bathing in should only be slightly more harmful than the X rays leaking out of my cheap "Made in Turdistan" TV set. I certainly wouldn't attempt using this setup with much more than a few watts of power. As for my attic dipoles, I have never tried to measure the exposure level in my home. I'll check in to that..but again, at 5w or less it can't be too dangerous. 73 -- ========================================= Radio Amateurs - Fill your junk box, from my junkbox! http://www.hamradparts.com 73 de KB9BVN ========================================= wrote in message news:e13sq1$fev@unix1.cc.ksu.edu... > >You'd have better luck with HF than VHF or UHF making it through any solid > >object. I have used a homebrew mag loop in a hotel room on several > >ocassions with some luck..on 20 and 40. > > Even in an emergency situation, I just don't think it would be a good idea > to string some kind of an antenna above the heads of shelterees and then > start soaking them with RF, especially depending on the HF frequency in > use. In fact, I suspect the FCC's RF-exposure regulations would frown on > one doing so! > > -- > --Myron A. Calhoun. > Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge > PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 > NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 97090 of rec.radio.amateur.homebrew From: "Rick Mintz" Subject: Plexi, Lexan or ??? Message-ID: Date: Fri, 07 Apr 2006 13:26:30 GMT Hi. I am building an amp and will be using a clear plastic over the front panel graphics. I could use some help in choosing the material, such as Plexi or Lexan. Since I will be drilling couple of 2" holes to mount panel meters, I need some suggestions for which material is the best to work with. A hole saw in Plexi is prone to crack and maybe there is a better choice. There also may be a better method for creating the holes than a standard hole saw. Suggestions??? de Rick W1TY Email: Rmintz@Rochester.rr.com Article: 97091 of rec.radio.amateur.homebrew From: "Rick Mintz" Subject: Drake Panel Meter Message-ID: Date: Fri, 07 Apr 2006 14:03:33 GMT Hi. Looking for the panel meter from a Drake W-4 wattmeter. This is the same meter as used in the MN-4, MN-2000, etc. Please reply direct. de Rick W1TY Rmintz@Rochester.rr.com