Article: 97134 of rec.radio.amateur.homebrew From: "Lynn Coffelt" Subject: Re: Regen with spider web coils ? Date: Wed, 12 Apr 2006 23:32:06 -0700 Message-ID: References: <1144845320.775026.160220@i39g2000cwa.googlegroups.com> wrote in message news:1144845320.775026.160220@i39g2000cwa.googlegroups.com... > Anybody built a regenerative receiver (tube or MOSFET :) using > oldschool spider web coils ? > In theory they have a very low amount of parasitic capacitance, and a > high Q. > Is it worth to use them for amateur bands ? Maybe not worth reading, but in the late 1940's I used a single 01A regen with homemade spider-web coils on the broadcast band. Probably was the root factor for Ms. Farnham kicking me out of high school Latin class. (for sleeping when I was supposed to be listening). From Washington State, XERF in Warez, Mexico came booming in until the wee morning hours. Oh, for the days of snake-oil medicines and Bible thumping! Technical notes: I did find that to find the best orientation for the antenna (with tickler) coil was critical. Using common masonite front panels ment that hand-capacitance greatly affected the amount of regeneration. Usually just left the coil flopping on its leads until the best compromise position was found, then invent a bracket or sticks and glue to hold it in position. Old Chief Lynn...... W7LTQ in 1948 Article: 97135 of rec.radio.amateur.homebrew From: fmmck@aol.com (Fred McKenzie) Subject: Re: Source of info on old transistors Date: Thu, 13 Apr 2006 11:26:46 -0400 Message-ID: References: In article , "Ronnie" wrote: > Anybody have a library of transistor databooks > from the early 60's? I'm trying to find technical > info on the following devices: Ronnie- With the exception of the 2N1192, most of your numbers don't sound like Motorola numbers. It may be that Motorola manufactured standard parts for a company, and marked them with that company's proprietary numbers instead. Under their agreements, Motorola is unlikely to provide any cross-reference information, requiring you to purchase replacements from the other company. Even other divisions of Motorola did this! There may be some cross-reference information, but it would help to know the manufacturer of the equipment the Motorola parts were used in. Have you tried a Google search for each of the numbers? 73, Fred, K4DII Article: 97136 of rec.radio.amateur.homebrew From: You Subject: Re: Lowering the noise figure in a preamp References: <1144845940.982676.234790@j33g2000cwa.googlegroups.com> <1144864101.042830.68540@u72g2000cwu.googlegroups.com> <1144865259.577289.156120@j33g2000cwa.googlegroups.com> Message-ID: Date: Thu, 13 Apr 2006 16:40:12 GMT In article <1144865259.577289.156120@j33g2000cwa.googlegroups.com>, "K7ITM" wrote: > As a point of reference, a typical NE3508M04 > (http://www.cel.com/pdf/datasheets/ne3508m04.pdf) can give you a device > noise figure under 0.4dB, operated at room temperature, at any > frequency across the entire "UHF" frequency range (300MHz to > 3GHz)--better than that at the lower end of the frequency range. > > Cheers, > Tom > Nothing like a Ruby Maser dumped in Liquid Nitrogen and pumped at -12 DBm to bring in those extremely small signals........ all it takes is cold...... Article: 97137 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Source of info on old transistors Date: Thu, 13 Apr 2006 13:52:05 -0500 Message-ID: References: "Fred McKenzie" wrote in message news:fmmck-1304061126460001@ac8c1454.ipt.aol.com... > In article , "Ronnie" > wrote: > > > Anybody have a library of transistor databooks > > from the early 60's? I'm trying to find technical > > info on the following devices: > > Ronnie- > > With the exception of the 2N1192, most of your numbers don't sound like > Motorola numbers. > > It may be that Motorola manufactured standard parts for a company, and > marked them with that company's proprietary numbers instead. Under their > agreements, Motorola is unlikely to provide any cross-reference > information, requiring you to purchase replacements from the other > company. Even other divisions of Motorola did this! > > There may be some cross-reference information, but it would help to know > the manufacturer of the equipment the Motorola parts were used in. > > Have you tried a Google search for each of the numbers? > > 73, Fred, K4DII Ronnie, I concurr. Those (non 2N numbers) are not "public" numbers, but "in-house" numbers belonging to the original equipment's manufacturer. I have some old references, but there IS stuff on the web. AllDataSheet gives some specs on the 2N1192: http://pdf1.alldatasheet.com/datasheet-pdf/view/120668/ETC/2N1192.html Alloy Junction Germanium Transistor PNP 200mw. 40 V Vcb 25 V Vce (R) whatever that means hfe 74 typ 2 MHz Ft TO-5 case 73, Steve, K9DCI Article: 97138 of rec.radio.amateur.homebrew Message-ID: <443EDCA9.4090006@nettally.com> From: **THE-RFI-EMI-GUY** Subject: Re: Lowering the noise figure in a preamp References: <1144845940.982676.234790@j33g2000cwa.googlegroups.com> <1144864101.042830.68540@u72g2000cwu.googlegroups.com> <1144865259.577289.156120@j33g2000cwa.googlegroups.com> <1144964968.399623.321100@u72g2000cwu.googlegroups.com> Date: Thu, 13 Apr 2006 23:17:40 GMT If your modulation is FM, the receiver audio is going to remain the same. And yes, the S meter will jump due to excess noise output of the preamplifier. The Excess gain will reduce the dynamic range of your receiver system and cause intermodulation (IM). 1. Connect a SINAD meter to your receiver . 2. Connect the Cushman directly to the receiver, adjust for +/- 3.0 KHz deviation with 1000 Hz tone. 3. Adjust Cushman generator for 12 dB SINAD 4. Note the generator output in dBm 5. Install preamplifier between Cushman and receiver 6. Adjust generator again for 12 dB SINAD 7. Note the generator output in dBm (should be more negative value than step 4) 8. The difference in dBm from steps 4 and 7 relate to the improvment (if any) in noise figure between the receiver alone and the receiver with the preamplifier. 9. Install a variable attenuator between output of preamplifier and input of receiver. Set to 0 dB attenuation. 10. Adjust generator for 12 dB SINAD 11. Adjust variable attenuator from step 9 until the 12 dB SINAD degrades slighly (numerically < 12 dB). 12. Readjust attenuator 1 dB per step until 12 dB SINAD is restored. 13. You have optimized your receiver and preamplifier for best intermodulation (IM) performance. 14. Install preamplifier close to antenna with a feedline, replace variable attenuator with fixed value equal to the value from step 12 minu the measured loss of the feedline between preamplifier and receiver. 15. If Cushman doesn't display dBM, use microvolts, fewer microvolts for 12 dB SINAD is the goal! 16. The above assumed an unmodified, properly operating preamplifier. Your preamplifier must have some sort of preselector filter between the antenna and it's input. Removing the stock filter exposes the preamplifier to overload from out of band signals, may affect the impedance (stability) of the preamplifier. Try operating it in its stock configuration and frequency prior to modifieing it. Then replace the stock filter with a properly tuned filter for the frequency you desire. Yes, you might have to retune the preamp if the frequency change is too far. Use the SINAD method and a low level signal to tweak the preamplifier sensitivity. Make sure your generator and cables are 50 ohms. A 10 dB 50 ohm pad between generator output and the system, may improve your results if the generator does not provide a 50 ohm source. tucker@conninc.com wrote: >Im guessing at the noise figure, im running a low level >1mv fr0m a >cushman service monitor to the preamp input. Im using a uniden 898t >scanner as a receiver because it has a digital S meter. When i turn on >the preamp jumps up 3-4 bars >but the modulation tone stays the same volume level. By this im >guessing the noise level has increased, the preamp had a ceramic >filter with the 50ohm input going directly into it and its output thur >cap to the 1st amp, the seller on ebay said just remove the filter and >move the input to the filters output trace, thats what i done but >results are poor even thou this is a commercial preamp pulled from >analog cell site. It looks to be a very well made preamp so it should >work if i figure out the >input match? > > > -- Joe Leikhim K4SAT "The RFI-EMI-GUY"İ "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P Article: 97139 of rec.radio.amateur.homebrew From: "stargatesg1" References: <1144845940.982676.234790@j33g2000cwa.googlegroups.com> <1144864101.042830.68540@u72g2000cwu.googlegroups.com> <1144865259.577289.156120@j33g2000cwa.googlegroups.com> <1144964968.399623.321100@u72g2000cwu.googlegroups.com> <443EDCA9.4090006@nettally.com> Subject: Re: Lowering the noise figure in a preamp Message-ID: Date: Fri, 14 Apr 2006 11:12:38 GMT Very nice write up dude! Just had to comment:-) 73's Rod "**THE-RFI-EMI-GUY**" wrote in message news:443EDCA9.4090006@nettally.com... > If your modulation is FM, the receiver audio is going to remain the > same. And yes, the S meter will jump due to excess noise output of the > preamplifier. The Excess gain will reduce the dynamic range of your > receiver system and cause intermodulation (IM). > > 1. Connect a SINAD meter to your receiver . > 2. Connect the Cushman directly to the receiver, adjust for +/- 3.0 KHz > deviation with 1000 Hz tone. > 3. Adjust Cushman generator for 12 dB SINAD > 4. Note the generator output in dBm > 5. Install preamplifier between Cushman and receiver > 6. Adjust generator again for 12 dB SINAD > 7. Note the generator output in dBm (should be more negative value than > step 4) > 8. The difference in dBm from steps 4 and 7 relate to the improvment (if > any) in noise figure between the receiver alone and the receiver with > the preamplifier. > > 9. Install a variable attenuator between output of preamplifier and > input of receiver. Set to 0 dB attenuation. > 10. Adjust generator for 12 dB SINAD > 11. Adjust variable attenuator from step 9 until the 12 dB SINAD > degrades slighly (numerically < 12 dB). > 12. Readjust attenuator 1 dB per step until 12 dB SINAD is restored. > 13. You have optimized your receiver and preamplifier for best > intermodulation (IM) performance. > 14. Install preamplifier close to antenna with a feedline, replace > variable attenuator with fixed value equal to the value from step 12 > minu the measured loss of the feedline between preamplifier and receiver. > > 15. If Cushman doesn't display dBM, use microvolts, fewer microvolts for > 12 dB SINAD is the goal! > > 16. The above assumed an unmodified, properly operating preamplifier. > Your preamplifier must have some sort of preselector filter between the > antenna and it's input. Removing the stock filter exposes the > preamplifier to overload from out of band signals, may affect the > impedance (stability) of the preamplifier. Try operating it in its stock > configuration and frequency prior to modifieing it. Then replace the > stock filter with a properly tuned filter for the frequency you desire. > Yes, you might have to retune the preamp if the frequency change is too > far. Use the SINAD method and a low level signal to tweak the > preamplifier sensitivity. Make sure your generator and cables are 50 > ohms. A 10 dB 50 ohm pad between generator output and the system, may > improve your results if the generator does not provide a 50 ohm source. > > > > > tucker@conninc.com wrote: > > >Im guessing at the noise figure, im running a low level >1mv fr0m a > >cushman service monitor to the preamp input. Im using a uniden 898t > >scanner as a receiver because it has a digital S meter. When i turn on > >the preamp jumps up 3-4 bars > >but the modulation tone stays the same volume level. By this im > >guessing the noise level has increased, the preamp had a ceramic > >filter with the 50ohm input going directly into it and its output thur > >cap to the 1st amp, the seller on ebay said just remove the filter and > >move the input to the filters output trace, thats what i done but > >results are poor even thou this is a commercial preamp pulled from > >analog cell site. It looks to be a very well made preamp so it should > >work if i figure out the > >input match? > > > > > > > > -- > Joe Leikhim K4SAT > "The RFI-EMI-GUY"İ > > "Treason doth never prosper: what's the reason? > For if it prosper, none dare call it treason." > > "Follow The Money" ;-P > Article: 97140 of rec.radio.amateur.homebrew From: Galen Watts Subject: Re: Lowering the noise figure in a preamp References: <1144845940.982676.234790@j33g2000cwa.googlegroups.com> <1144864101.042830.68540@u72g2000cwu.googlegroups.com> <1144865259.577289.156120@j33g2000cwa.googlegroups.com> Message-ID: Date: Fri, 14 Apr 2006 12:10:06 GMT You wrote: > In article <1144865259.577289.156120@j33g2000cwa.googlegroups.com>, > "K7ITM" wrote: > > >>As a point of reference, a typical NE3508M04 >>(http://www.cel.com/pdf/datasheets/ne3508m04.pdf) can give you a device >>noise figure under 0.4dB, operated at room temperature, at any >>frequency across the entire "UHF" frequency range (300MHz to >>3GHz)--better than that at the lower end of the frequency range. >> >>Cheers, >>Tom >> > > > Nothing like a Ruby Maser dumped in Liquid Nitrogen and pumped at > -12 DBm to bring in those extremely small signals........ > > all it takes is cold... It still takes cold but InP HEMTs perform much better than ruby masers these days... "Extremely Low-Noise Amplification with Cryogenic FET's and HFET's: 1970-2004" http://www.gb.nrao.edu/electronics/edir/edir314.pdf Happy reading! -Galen, W8LNA Article: 97141 of rec.radio.amateur.homebrew From: "Eike Lantzsch, ZP6CGE" Subject: Does cured Epoxy absorb microwaves? Date: Fri, 14 Apr 2006 08:58:27 -0400 Message-ID: I know that microwaves are sometimes used to cure epoxy but does cured epoxy absorb microwaves? More practically put: can I use epoxy to glue some parts of a double quad for 2.4GHz? Kind regards, Eike -- "The adventurs may be mad, but the adventurer must be sane." - G. K. Chesterton (1908) Article: 97142 of rec.radio.amateur.homebrew From: "Paul VK3DIP" References: <1142687392.568430.122110@e56g2000cwe.googlegroups.com> <7SLXf.22113$dy4.15868@news-server.bigpond.net.au> Subject: Re: Return Loss Bridge Accuracy Questions Message-ID: Date: Fri, 14 Apr 2006 13:17:09 GMT Christer, It looks like Rockby has sold out and removed them from their catalogue, the one you pointed out is indeed not the correct part. The ones I used are as far as I know a standard/common 14mm balun former as used in TV baluns etc.. The Jaycar (www.jaycar.com.au), or Electus (http://www.electusdistribution.com.au) part number LF1220 looks basically identical to those I used, and there are probably lots of equivalents out there. Electus has some data on the M7 material used here http://www.electusdistribution.com.au/images_uploaded/ferrites.pdf I hope this helps, and I would be interested in how you get on if you end up building one, let me know at the email address shown below. 73 Paul VK3DIP pmcmahon@telstra.com "CA" wrote in message news:gS5%f.52591$d5.207697@newsb.telia.net... > Paul VK3DIP wrote: > >> 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... > > I have read your article with great interest. > Do you have a specification for the "balun formers" or maybe a Rockby > Electronics stock no.? > I suppose it is www.rockby.com.au. The only 2-hole ferrite core I could > find is stock no. 10967 but I believe this one is too small. > > 73 > Christer SM6PXJ > > Article: 97143 of rec.radio.amateur.homebrew From: "Mike Andrews" Subject: Re: Does cured Epoxy absorb microwaves? Date: Fri, 14 Apr 2006 14:21:07 +0000 (UTC) Message-ID: References: Eike Lantzsch, ZP6CGE wrote: > I know that microwaves are sometimes used to cure epoxy but does > cured epoxy absorb microwaves? More practically put: can I use > epoxy to glue some parts of a double quad for 2.4GHz? Your best source of information here will be the manufacturer. Next best will be to put a test object (made of things that don't absorb microwaves) glued with the epoxy in your microwave with a cup of water and heat it until the water boils. If the test object isn't uncomfortably hot, the epoxy probably is OK for use in your quad. Microwave ovens here in the US seem to run around 2.45 GHz, which is fairly close to your working frequency, so the test will be a fairly good indication. -- Mike Andrews, W5EGO mikea@mikea.ath.cx Tired old sysadmin Article: 97144 of rec.radio.amateur.homebrew From: "Ronnie" References: <1144987740.390686.297810@g10g2000cwb.googlegroups.com> Subject: Re: Source of info on old transistors Message-ID: <4jO%f.1803$Lm5.1016@newssvr12.news.prodigy.com> Date: Fri, 14 Apr 2006 14:27:12 GMT Thanks Fred, Steve, Tom: I think you guys are correct about these being house numbered devices. They are from an old Piper autopilot that was manufactured for Piper by Mitchell Industries of Mineral Wells, TX (now Century Flight Systems). I noticed that 2 of the 12 power transistors had been replaced at some point in time and are marked with "Mitchell Industries MN92". Since this was an avionics application, it is likely that these were marked specifically for Mitchell, initially with the 48S23 device number and then later with Mitchell's name and MN92 marking. I've made an attempt to see what information Centrury Flight Systems is able and/or willing to provide, but so far they have not been too responsive. I'm also looking for a spare amplifier from the aircraft salvage yards and avionics shops. My main interest in all of this was to generate a schematic of the amplifier and do a bit of reverse engineering in order to better understand the overall design of the system. The service manual for the autopilot system did not include a schematic or any details of the amplifier. Thanks again for the help. Ronnie "K7ITM" wrote in message news:1144987740.390686.297810@g10g2000cwb.googlegroups.com... > As Fred and Steve noted, you have a bunch of "house-numbered" > transistors, and one that's relatively easy. Actually, the MA900 seems > to be from a series of germanium parts. I have numbers on both sides > of it, but not that particular one, in my book. I do have a full > Motorola data sheet on the 2N1192, in my 1969 Motorola "Semiconductor > Data Book." Since I'm about to scan something else, I scanned it into > a PDF (as images, not text). It's not great, but it's legible. Email > me if you'd like a copy. > > Cheers, > Tom > Article: 97145 of rec.radio.amateur.homebrew From: "Mike Rhoads" Subject: freeware for determining mixer products? Message-ID: Date: Fri, 14 Apr 2006 15:29:59 GMT I have a receiver I am considering modifying for other bands outside of what it covers. It is a dual conversion superhet design. Before I modify it, I'd like to see how the new frequencies would affect the mixer output. Is there any decent freeware available that would allow me to see all mixer outputs and to determine if any outputs might be a problem? Thanks, Mike Article: 97146 of rec.radio.amateur.homebrew From: "Ronnie" References: <1144987740.390686.297810@g10g2000cwb.googlegroups.com> <4jO%f.1803$Lm5.1016@newssvr12.news.prodigy.com> <1145027699.517576.210170@g10g2000cwb.googlegroups.com> Subject: Re: Source of info on old transistors Message-ID: Date: Fri, 14 Apr 2006 16:04:36 GMT Tome, I agree with all you've said. In general the autopliot amp is a DC circuit and has a slow response time. However, this system does generate RF signals which are used to sense the pitch and roll attitude and the postion of the servos. This autopilot system uses variable inductors to sense pitch and bank information from the attitude gyro. Each one consists of an iron and aluminum metal vane attached to the corresponding axis of the atitude gyro which moves in front of a iron core coil as a pick up. I found a test box designed for the system that includes a jack that provides a dummy AI gyro allowing the substituion of its inductors in place of the actual gyro for bench testing. It contains standard looking RF coils with tunable slugs. The service manual states an operating frequency of 10 MHz, but that is stated only as an exmaple. I'm not sure it that is the actual freq or not. The resonant frequency is determined by the inductance in the AI gyro, air variable caps in the servos and some variable air caps used for trim and centering adjustments. The circuirt is arranged so that as the airplane changes pitch or bank, the changes in reactance cause the circuit to change frequency. A discriminator in the amp detects the frequency change, produces a DC voltage which is amplified to drive the servo motor in the appropriate direction to bring the circuit back into resonnance via the feedback caps that sense servo postion. This or course moves the control surfaces and brings the airplane back to level flight attitude. The components are connected together with specific lengths of low capacitance cable. The cable and connectors appear to be very similar to that used in GM automobiles in the 1960s. At least my 1966 Pontiac had a similar cable and connector from the antenna to the radio. It is a hollow plastic tube with a very small center conductor that is loosely coiled inside the plastic tube. There is a braided shield over the outside of the plastic tube, and a outer jacket over that. Some people have pointed out it is very similar to RG-62, 93 ohm coax without the spirial wound center insulator / spacer. I measured about 10.5 pF per foot on a 28" piece of this cable with connectors installed on each end. This has been quite a project. I basically have seen all the components work in the airplane at various times, but the system as a whole is intermittent. Most time the wing leveler funciton works correctly but once in a while it wants to turn right. The pitch circuit has been working but is now acting up. The altitude hold was badly out of adjustment, but I was able to get that setup properly and working, but the climb and descent airspeeds are not right yet. I'm not sure if I've got bad connections, intermittent components in the amplifier or both. I'm planning to pull the cable assemblies out along with the amplifier and get it on the bench for testing. Therefore, it would sure help to have a basic understadning of the amp circuit during that process. Therefore, I thought learning about the transistors charateristics and the inductance values would be helpful. I've already measured all the cap values and ranges. Next step is to generate a schematic for the amp and learn how it is supposed to work. It might also be fun to design and built a replacement for the amplifier using modern components. Thanks again for your help. Ronnie "K7ITM" wrote in message news:1145027699.517576.210170@g10g2000cwb.googlegroups.com... > >From that era, and from what you know so far (that they are apparently > pretty much all germanium parts), it shouldn't be too difficult to > deduce how it worked. It's unlikely any of the active parts are > particularly esoteric. Usually you can figure out the polarity of the > parts from the schematic, and assuming about 0.3V for forward junction > bias and current gains typical of the power and signal transistors then > in use should get you close to what you need. I suppose nothing in an > autopilot needs to be very fast, so it's very unlikely any are RF > transistors. It's possible that the circuit requires close tolerance > on some feature (like gain), but that's poor circuit design and I'd > hope for better of them. Once you have a circuit diagram, maybe you > could try "spicing" it, if you're not comfortable with a simple paper > analysis. > > Good luck with it. > > Cheers, > Tom > Article: 97148 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: freeware for determining mixer products? Date: Fri, 14 Apr 2006 14:36:58 -0500 Message-ID: References: Oh boy! In the olden days I have seen mixer products charts. I think the idea was to plot the places where all the harmonics of the two inputs produced products so you could pick an L.O. and IF which didn't have problems. However, I'm at a loss to point to anything. I probably have one buried in the reams of stuff I saved to use in the future...argggg I'm sure Excel can do this if you want to put in all the formulas (and know what to calculate) 73, Steve, K9DCI Perhaps a search on mixing charts or similar terms... Hmmmm Googling this got nil: Receiver mixer "mixing charts" -"23-channel" "Mike Rhoads" wrote in message news:XdP%f.6978$i41.2958@newsread1.news.atl.earthlink.net... > I have a receiver I am considering modifying for other bands outside of what > it covers. It is a dual conversion superhet design. Before I modify it, > I'd like to see how the new frequencies would affect the mixer output. Is > there any decent freeware available that would allow me to see all mixer > outputs and to determine if any outputs might be a problem? > > Thanks, > Mike > > Article: 97149 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Source of info on old transistors Date: Fri, 14 Apr 2006 14:42:49 -0500 Message-ID: References: <1144987740.390686.297810@g10g2000cwb.googlegroups.com> <4jO%f.1803$Lm5.1016@newssvr12.news.prodigy.com> <1145031391.175280.315900@e56g2000cwe.googlegroups.com> "Ronnie" wrote in message news:olQ%f.69733$dW3.64843@newssvr21.news.prodigy.com... > Thanks Harry. > > I do have a service manual for the system published > by Piper, ... I'm also > trying to find out what help the orginal manufacture > can be. It really helps to know how to throw yourself on the mercy of some marketing type to get to an Engineer who is willing to spill his guts or, give away the keys to the kingdom and send you a schematic and info. Done a lot of that over the many years as a Engineer-Ham...or is that Ham-Engineer. 73, Steve, K9DCI Article: 97150 of rec.radio.amateur.homebrew From: "Erik Waterhouse" References: <1145038796.634811.265160@i39g2000cwa.googlegroups.com> Subject: Re: freeware for determining mixer products? Message-ID: Date: Fri, 14 Apr 2006 20:27:09 GMT Thanks! Already downloading it! "K7ITM" wrote in message news:1145038796.634811.265160@i39g2000cwa.googlegroups.com... > The free RFSim99 package, which has a wonderful set of tools just in > the RFSim99 application itself, also includes a separate program called > "Spur Search" which should do just what you want. A Google or similar > search should turn up several places from which you can download > RFSim99. > > Cheers, > Tom > Article: 97151 of rec.radio.amateur.homebrew From: dplatt@radagast.org (Dave Platt) Subject: Re: freeware for determining mixer products? Date: Fri, 14 Apr 2006 21:17:34 -0000 Message-ID: <12404beks815mb9@corp.supernews.com> References: In article , Steve Nosko wrote: >Oh boy! In the olden days I have seen mixer products charts. I think the >idea was to plot the places where all the harmonics of the two inputs >produced products so you could pick an L.O. and IF which didn't have >problems. However, I'm at a loss to point to anything. I probably have one >buried in the reams of stuff I saved to use in the future...argggg >I'm sure Excel can do this if you want to put in all the formulas (and know >what to calculate) Shouldn't be dreadfully hard, I think. Assuming two frequencies F1 and F2, you'll get mixing products at the sum (F1+F2) and difference (abs(F1-F2)). To deal with harmonics and higher-order mixing products, I believe you can generalize this by including two integer multiplier factors M and N whose values run from 1 up to as high as you care to go. Then, expect mixing products to be at (M*F1)+(N*F2) and abs((M*F1)-(N*F2)). The amplitudes of the mixing products will be lower as the multipliers go up... you could probably kluge in an estimation formula of some sort. Calculate the various mixing frequencies, and estimated levels in a square matrix, link the data to a two-column arrangement, and generate a plot of level vs. frequency. -- 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: 97152 of rec.radio.amateur.homebrew Message-ID: <44404805.1060709@nettally.com> From: **THE-RFI-EMI-GUY** Subject: Re: Lowering the noise figure in a preamp References: <1144845940.982676.234790@j33g2000cwa.googlegroups.com> <1144864101.042830.68540@u72g2000cwu.googlegroups.com> <1144865259.577289.156120@j33g2000cwa.googlegroups.com> <1144964968.399623.321100@u72g2000cwu.googlegroups.com> <443EDCA9.4090006@nettally.com> Date: Sat, 15 Apr 2006 01:07:58 GMT This is a multi-part message in MIME format. --------------070700020500090407020300 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Thanks! stargatesg1 wrote: >Very nice write up dude! Just had to comment:-) > >73's >Rod > >"**THE-RFI-EMI-GUY**" wrote in message >news:443EDCA9.4090006@nettally.com... > > >>If your modulation is FM, the receiver audio is going to remain the >>same. And yes, the S meter will jump due to excess noise output of the >>preamplifier. The Excess gain will reduce the dynamic range of your >>receiver system and cause intermodulation (IM). >> >>1. Connect a SINAD meter to your receiver . >>2. Connect the Cushman directly to the receiver, adjust for +/- 3.0 KHz >>deviation with 1000 Hz tone. >>3. Adjust Cushman generator for 12 dB SINAD >>4. Note the generator output in dBm >>5. Install preamplifier between Cushman and receiver >>6. Adjust generator again for 12 dB SINAD >>7. Note the generator output in dBm (should be more negative value than >>step 4) >>8. The difference in dBm from steps 4 and 7 relate to the improvment (if >>any) in noise figure between the receiver alone and the receiver with >>the preamplifier. >> >>9. Install a variable attenuator between output of preamplifier and >>input of receiver. Set to 0 dB attenuation. >>10. Adjust generator for 12 dB SINAD >>11. Adjust variable attenuator from step 9 until the 12 dB SINAD >>degrades slighly (numerically < 12 dB). >>12. Readjust attenuator 1 dB per step until 12 dB SINAD is restored. >>13. You have optimized your receiver and preamplifier for best >>intermodulation (IM) performance. >>14. Install preamplifier close to antenna with a feedline, replace >>variable attenuator with fixed value equal to the value from step 12 >>minu the measured loss of the feedline between preamplifier and receiver. >> >>15. If Cushman doesn't display dBM, use microvolts, fewer microvolts for >>12 dB SINAD is the goal! >> >>16. The above assumed an unmodified, properly operating preamplifier. >>Your preamplifier must have some sort of preselector filter between the >>antenna and it's input. Removing the stock filter exposes the >>preamplifier to overload from out of band signals, may affect the >>impedance (stability) of the preamplifier. Try operating it in its stock >>configuration and frequency prior to modifieing it. Then replace the >>stock filter with a properly tuned filter for the frequency you desire. >>Yes, you might have to retune the preamp if the frequency change is too >>far. Use the SINAD method and a low level signal to tweak the >>preamplifier sensitivity. Make sure your generator and cables are 50 >>ohms. A 10 dB 50 ohm pad between generator output and the system, may >>improve your results if the generator does not provide a 50 ohm source. >> >> >> >> >>tucker@conninc.com wrote: >> >> >> >>>Im guessing at the noise figure, im running a low level >1mv fr0m a >>>cushman service monitor to the preamp input. Im using a uniden 898t >>>scanner as a receiver because it has a digital S meter. When i turn on >>>the preamp jumps up 3-4 bars >>>but the modulation tone stays the same volume level. By this im >>>guessing the noise level has increased, the preamp had a ceramic >>>filter with the 50ohm input going directly into it and its output thur >>>cap to the 1st amp, the seller on ebay said just remove the filter and >>>move the input to the filters output trace, thats what i done but >>>results are poor even thou this is a commercial preamp pulled from >>>analog cell site. It looks to be a very well made preamp so it should >>>work if i figure out the >>>input match? >>> >>> >>> >>> >>> >>-- >>Joe Leikhim K4SAT >>"The RFI-EMI-GUY"İ >> >>"Treason doth never prosper: what's the reason? >>For if it prosper, none dare call it treason." >> >>"Follow The Money" ;-P >> >> >> > > > > -- Joe Leikhim K4SAT "The RFI-EMI-GUY"İ "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P --------------070700020500090407020300 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Thanks!

stargatesg1 wrote:
Very nice write up dude! Just had to comment:-)

73's
Rod

"**THE-RFI-EMI-GUY**" <rhyolite@nettally.com> wrote in message
news:443EDCA9.4090006@nettally.com...
  
If your modulation is FM, the receiver audio is going to remain the
same. And yes, the S meter will jump due to excess noise output of the
preamplifier. The Excess gain will reduce the dynamic range of your
receiver system and cause intermodulation (IM).

1. Connect a SINAD meter to your receiver .
2. Connect the Cushman directly to the receiver, adjust for +/- 3.0 KHz
deviation with 1000 Hz tone.
3. Adjust Cushman generator for 12 dB SINAD
4. Note the generator output in dBm
5. Install preamplifier between Cushman and receiver
6. Adjust generator again for 12 dB SINAD
7. Note the generator output in dBm (should be more negative value than
step 4)
8. The difference in dBm from steps 4 and 7 relate to the improvment (if
any) in noise figure between the receiver alone and the receiver with
the preamplifier.

9. Install a variable attenuator between output of preamplifier and
input of receiver. Set to 0 dB attenuation.
10. Adjust generator for 12 dB SINAD
11. Adjust variable attenuator from step 9 until the 12 dB SINAD
degrades slighly (numerically < 12 dB).
12. Readjust attenuator 1 dB per step until 12 dB SINAD is restored.
13. You have optimized your receiver and preamplifier for best
intermodulation (IM) performance.
14. Install preamplifier close to antenna with a feedline, replace
variable attenuator with fixed value equal to the value from step 12
minu the measured loss of the feedline between preamplifier and receiver.

15. If Cushman doesn't display dBM, use microvolts, fewer microvolts for
12 dB SINAD is the goal!

16. The above assumed an unmodified, properly operating preamplifier.
Your preamplifier must have some sort of preselector filter between the
antenna and it's input. Removing the stock filter exposes the
preamplifier to overload from out of band signals, may affect the
impedance (stability) of the preamplifier. Try operating it in its stock
configuration and frequency prior to modifieing it. Then replace the
stock filter with a properly tuned filter for the frequency you desire.
Yes, you might have to retune the preamp if the frequency change is too
far. Use the SINAD method and a low level signal to tweak the
preamplifier sensitivity. Make sure your generator and cables are 50
ohms. A 10 dB 50 ohm pad between generator output and the system, may
improve your results if the generator does not provide a 50 ohm source.




tucker@conninc.com wrote:

    
Im guessing at the noise figure, im running a low level >1mv fr0m a
cushman service monitor to the preamp input. Im using a uniden 898t
scanner as a receiver because it has a digital S meter.  When i turn on
the preamp jumps up 3-4 bars
but the modulation tone stays the same volume level. By this im
guessing the noise level has increased,  the preamp had a ceramic
filter with the 50ohm input going directly into it and its output thur
cap to the 1st amp,  the seller on ebay said just remove the filter and
move the input to the filters output trace, thats what i done but
results are poor even thou this is a commercial preamp pulled from
analog cell site.  It looks to be a very well made preamp so it should
work if i figure out the
input match?



      
-- 
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P

    


  

-- 
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P
--------------070700020500090407020300-- Article: 97153 of rec.radio.amateur.homebrew From: Alfred Green Subject: Accurate voltage calibration Message-ID: Date: Fri, 14 Apr 2006 19:47:03 -0700 I have recently aquired a nice 5.1/2 digit DVM, and would like to assess the absolute accuracy. Many years ago I had a 'Standard Cell', but that got lost in one of my several relocations. What is a good alternative these days? I would think that there is a semiconductor device that has a known threshold. I am familiar with the Wheatstone bridge method to measure voltage without affecting the reference. Once I have a good DC reference, getting AC & RMS calibration is fairly easy. Having a GPS locked time and frequency reference, I am used to being at the 1e-10 accuracy level for those, but if I can get to 1e-5 for analog voltage I would be very happy. Any suggestions gratefully received. 73 Alf NU8I Scottsdale AZ DM43an 160m - 10 Gigs Article: 97155 of rec.radio.amateur.homebrew From: "Alex" References: <27AZf.72889$A83.1739689@twister1.libero.it> Subject: Re: IC756/TL922 keying - Any Suggestion? Message-ID: Date: Sun, 16 Apr 2006 17:43:58 GMT "Highland Ham" wrote: > Would a high voltage switching transistor with/without an opto-coupler > circuit not be more reliable ? > The opto-coupler circuit can be tailored for the transceiver's output > and a cheap High Voltage transistor could excite the amplifier. > Just a thought. > > Frank GM0CSZ / KN6WH ---------------------------------------------------------------------------- --- Many thanks Frank i'm searching for this kind of circuit, have you a printable (.jpg, .bmp, .gif, .tif etc.)) version with the complete parts list? best 73 de Alex IK8XIR / N6XIR Article: 97156 of rec.radio.amateur.homebrew From: internetDotComs.com Subject: for sale: internetDotComs.com Date: Sun, 16 Apr 2006 19:47:31 +0200 Message-ID: domain for sale: internetdotcoms.com http://www.afternic.com/name.php?id=11866440 Article: 97157 of rec.radio.amateur.homebrew From: "Alex" References: <27AZf.72889$A83.1739689@twister1.libero.it> Subject: Re: IC756/TL922 keying - Any Suggestion? Message-ID: Date: Sun, 16 Apr 2006 17:53:23 GMT "on4ahf" wrote > Use an extern relais , otherwise you burn the very little tx relais (my > friend dit it with the tl922 ) > because the key voltage is 120v > suc6 > Thank you for your help, I know that (about the very little reed relay inside the rtx), for this reason i'm searching for a electronic circuit, with an switching absorption "greater" less than 500mA @ 16Vdc (as declared by Icom). A transistor feat. circuit i believe will be fine. 73 de Alex IK8XIR / N6XIR Article: 97158 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA:VIBROPLEX BUG,amp parts,tubes,+stuff Message-ID: Date: Sun, 16 Apr 2006 18:12:01 GMT Vibroplex 'Presentation' in original box, more amp parts, tubes, fixed vac caps, + other stuff too; see at http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy tnx for looking: more tubes and 'stuff' coming--check back often: heytubeguy Article: 97159 of rec.radio.amateur.homebrew From: bg998@FreeNet.Carleton.CA (Martin Potter) Subject: Re: Does cured Epoxy absorb microwaves? Date: 17 Apr 2006 00:28:18 GMT Message-ID: References: "Eike Lantzsch, ZP6CGE" (eikelan@gmx.net) writes: > I know that microwaves are sometimes used to cure epoxy but does > cured epoxy absorb microwaves? More practically put: can I use > epoxy to glue some parts of a double quad for 2.4GHz? > Not sure if it is relevant to modern materials, but when I worked for the National Research Council (Canada) many years ago, I used to make dummy loads by mixing a powdered ferrite material with the then-available epoxy cement and pouring a tapered slab of this mix into the waveguide. (These were used as the flat load at liquid nitrogen temperatures in a Dicke radiometer at S and X bands.) ... Martin VE3OAT Article: 97160 of rec.radio.amateur.homebrew From: fmmck@aol.com (Fred McKenzie) Subject: The Perfect Gift: A Tool Box Date: Mon, 17 Apr 2006 17:13:18 -0400 Message-ID: Most everyone has a screwdriver or two laying around the house, but not everyone has a minimum collection stored in a tool box. If you know a young person graduating from high school, a single relative, or even yourself, a tool box with a minimum complement of tools may be the perfect gift. Based on my own experience, the BASIC TOOL BOX should include: A plastic or metal box such as the 13² plastic box from Walmart or the 14² plastic box from Lowes. The box should have a secure latch that wonıt come open when picked up. #1 Philips screwdriver #2 Philips screwdriver 1/8² Flat blade screwdriver 1/4² Flat blade screwdriver Standard pair of slip-joint pliers with insulated handle Diagonal cutters with insulated handle Long nose pliers with side cutter and insulated handle Small claw hammer such as Sears 3805 - 7 oz. Depending on your knowledge of the individualıs needs and the size of the box, additional items might include: Full-size hammer Crowbar or pry-lever Flashlight Tire pressure gauge(s) Pocket knife & sharpening stone Soldering iron & solder & soldering braid Digital multimeter Set of nut drivers Set of Allen wrenches Set of Torx drivers You get the idea! 73, Fred, K4DII Article: 97161 of rec.radio.amateur.homebrew From: jakdedert Subject: Re: The Perfect Gift: A Tool Box References: Message-ID: Date: Mon, 17 Apr 2006 16:41:02 -0500 Fred McKenzie wrote: > Most everyone has a screwdriver or two laying around the house, but not > everyone has a minimum collection stored in a tool box. If you know a > young person graduating from high school, a single relative, or even > yourself, a tool box with a minimum complement of tools may be the perfect > gift. > > Based on my own experience, the BASIC TOOL BOX should include: > > A plastic or metal box such as the 13² plastic box from Walmart or the 14² > plastic box from Lowes. The box should have a secure latch that wonıt > come open when picked up. > > #1 Philips screwdriver > > #2 Philips screwdriver > > 1/8² Flat blade screwdriver > > 1/4² Flat blade screwdriver > > Standard pair of slip-joint pliers with insulated handle > > Diagonal cutters with insulated handle > > Long nose pliers with side cutter and insulated handle > > Small claw hammer such as Sears 3805 - 7 oz. > > Depending on your knowledge of the individualıs needs and the size of the > box, additional items might include: > > Full-size hammer > > Crowbar or pry-lever > > Flashlight > > Tire pressure gauge(s) > > Pocket knife & sharpening stone > > Soldering iron & solder & soldering braid > > Digital multimeter > > Set of nut drivers > > Set of Allen wrenches > > Set of Torx drivers > > You get the idea! > > 73, Fred, K4DII > Dunno why it didn't occur to me...thankfully it 'did' occur to my wife: Bought almost the exact (above) setup for my prospective son-in-law for Christmas. He's mechanically dis-inclined. We're gonna fix that. Can't have a s-in-l who can't fix stuff.... jak Article: 97162 of rec.radio.amateur.homebrew From: Alfred Green Subject: Re: Accurate voltage calibration References: <1145097545.334257.20180@e56g2000cwe.googlegroups.com> Message-ID: Date: Mon, 17 Apr 2006 17:20:40 -0700 Leon wrote: > Alfred Green wrote: > >>I have recently aquired a nice 5.1/2 digit DVM, and would like to assess >>the absolute accuracy. Many years ago I had a 'Standard Cell', but that >>got lost in one of my several relocations. > > I don't think there is an easy to do what you want, otherwise people > wouldn't spend lots of money getting their standards calibrated at > national standards labs like NPL. Your best bet might be to find > someone who has access to a regularly calibrated DVM and check it > against that, or send it away to get it calibrated. > Well, maybe askimg for 1e-5 was very optimistic, but I would like to see what can be done in a home environment. For ham use I couldn't justify getting it professionally calibrated, but I'll check with the test-equipment guy at work to see if we have something recently done that I can do a comparison from. > Standard voltage diodes are available and are used as secondary > standards, but are probably quite expensive and difficult to find. > That was kind of what I was looking for. I really am prepared to pay a few bob for something that I can reliably use as a reference in my lab. > You should have kept your Weston cell. 8-) BTW, NPL even offers a > calibration service for them, the volt is defined using a Josephson > junction, these days. > Oh yep. I think it was amongst the stuff that got lost in the move from UK to the States back in '85. They do show up on Ebay occaisionally, but I'd like to think there was something newer that could do the job. Interesting to hear about the current Volt definition: I'll do some searching for some more info on that. Thanks for your comments, 73 Alf NU8I (aka G4ABB, amongst others) Article: 97163 of rec.radio.amateur.homebrew From: Alfred Green Subject: Re: Accurate voltage calibration References: <1145112749.276559.84010@u72g2000cwu.googlegroups.com> Message-ID: Date: Mon, 17 Apr 2006 17:53:05 -0700 K7ITM wrote: > I'd suggest you either find a calibrator to connect your meter to, or > make something you can use as a transfer standard. Maxim, for example, > has some reasonably low cost voltage references with good stability > (very few ppm/C). Yes, that's pretty much what I'm looking for. The only problem with Maxim is that they have SO MUCH good stuff it makes it hard for me to find what I'm looking for. I'll try a more directed search. > Then calibrate the transfer standard against some > known in-calibration volt meter or calibrator, at a known temperature, > and use it. Yes, I can do that. I already have a temperature controlled environment for my frequency sources. > I'd think in Scottsdale you could find a calibration > service that would do the job for you, or maybe you know someone who > has access to an accurate voltmeter. Of course, you should really do > it for several ranges. You can maybe calibrate a voltage divider > yourself, but it would save a lot of trouble if you could just do it > directly. If you don't know anyone who works with more accurate > instruements regularly and don't want to pay for a calibration, perhaps > you could pay a visit to the EE or physics department in Tempe and use > one of their instruments. > All good points. I have friends at ASU that could help with this, but at the end of the day it still has to come home with me. Back to the transfer standard issue. > I've thought of making a secondary standard myself--I have several of > the reference boards from HP3455 DMMs that have single specific things > wrong with them, but combining them I have at least one good voltage > reference, and one good DC 10:1 divider. > Hmm. The unit in question is a HP3478A. It has a 'CAL' button, but I haven't hunted for a manual yet so I dont know what it does. Any ideas? > Don't EVER expect to get to voltage measurements with accuracy or even > repeatability like you can with frequency Oh no, I wasn't expecting that. Even my comment about 1e-5 was really tongue-in-cheek. However, I really can't point to anything in my shack that can even approach 1e-2 in any repeatable way as far as voltage or current measurement goes. I just feel that in this day and age I should be able to do better that that. 73 Alf NU8I Article: 97164 of rec.radio.amateur.homebrew From: fmmck@aol.com (Fred McKenzie) Subject: Re: The Perfect Gift: A Tool Box Date: Mon, 17 Apr 2006 23:18:19 -0400 Message-ID: References: In article , Highland Ham wrote: > What about Posidrive screwdrivers ? These are similar to Philips type of > screwdrivers but have additional 'notches' (if that is the correct word) > for better grip . The relevant screw heads are accordingly. Frank- I've heard of Posidrive. I think they are used in an old Hewlett Packard counter I have. However, the tool dealers I asked had never heard of them. I ended up using a common Phillips driver for my counter. Certainly Posidrive would be a better choice where they are more commonly used. Fred Article: 97165 of rec.radio.amateur.homebrew From: "Mr Fed UP" References: Subject: Re: The Perfect Gift: A Tool Box Message-ID: Date: Tue, 18 Apr 2006 00:04:42 -0500 Heh heh dont forget the asprin and $50 for the headache and one tool you'll always have to go get for each job. And a 6" or 8" knuckle buistin adjustable wrench. LOL Good luck K4TWO Gary "Fred McKenzie" wrote in message news:fmmck-1704061713180001@ac801112.ipt.aol.com... > > Most everyone has a screwdriver or two laying around the house, but not > everyone has a minimum collection stored in a tool box. If you know a > young person graduating from high school, a single relative, or even > yourself, a tool box with a minimum complement of tools may be the perfect > gift. > > Based on my own experience, the BASIC TOOL BOX should include: > > A plastic or metal box such as the 13² plastic box from Walmart or the 14² > plastic box from Lowes. The box should have a secure latch that wonıt > come open when picked up. > > #1 Philips screwdriver > > #2 Philips screwdriver > > 1/8² Flat blade screwdriver > > 1/4² Flat blade screwdriver > > Standard pair of slip-joint pliers with insulated handle > > Diagonal cutters with insulated handle > > Long nose pliers with side cutter and insulated handle > > Small claw hammer such as Sears 3805 - 7 oz. > > Depending on your knowledge of the individualıs needs and the size of the > box, additional items might include: > > Full-size hammer > > Crowbar or pry-lever > > Flashlight > > Tire pressure gauge(s) > > Pocket knife & sharpening stone > > Soldering iron & solder & soldering braid > > Digital multimeter > > Set of nut drivers > > Set of Allen wrenches > > Set of Torx drivers > > You get the idea! > > 73, Fred, K4DII Article: 97166 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: The Perfect Gift: A Tool Box Date: Mon, 17 Apr 2006 22:12:35 -0700 Message-ID: <1248ta74cr2pm3e@corp.supernews.com> References: Fred McKenzie wrote: > I've heard of Posidrive. I think they are used in an old Hewlett Packard > counter I have. However, the tool dealers I asked had never heard of > them. I ended up using a common Phillips driver for my counter. > > Certainly Posidrive would be a better choice where they are more commonly used. I'd consider looking for some other tool dealers to do business with. Pozidriv (a registered trademark of Phillips Screw Co.) screws and drivers are very common, sold by just about every tool company from Snap-on through Stanley to Sears. Tektronix used Pozidriv screws exclusively for many years, until they converted over to Torx. A standard Phillips bit fits poorly in a Pozidriv screw, making it really easy to chew up the screw with this combination. Any decent toolbox should include some Pozidriv drivers or bits. Roy Lewallen, W7EL Article: 97167 of rec.radio.amateur.homebrew From: mike Subject: Finding short duration interference? Date: Tue, 18 Apr 2006 03:40:12 -0700 Message-ID: <1249ghuscr3fneb@corp.supernews.com> What's a good method for finding short duration interference? My 440 repeater is plagued by an interfering signal that lasts a small fraction of a second, just long enough to bring up the repeater, and repeats randomly every 20 seconds or so. Comes and goes...Seems to be dependent on outside temperature. Sometimes sounds like there's hum on the signal. First thought was that it was one of those oscillating Winegard RV TV antennas, but it doesn't seem to drift around like they typically do. I hooked the repeater antenna up to the spectrum analyzer, but the duration is too short to get thru the filters at the bandwidth required to get any sensitivity. I can hear it on the mobile. I've driven around the neighborhood, but the duration is so short that I've not been able to track it down. Strength seems to peak at different places blocks apart...but it's hard to tell. I have some experience with a double duckey and started designing a doppler system, but it occurs that the short duration signal will be completely washed out by the Switched Cap Filter. Don't see how I'm gonna get the low rep-rate signal past the noise. Filter types that I know about ain't gonna work. Ideas? Thanks, mike Article: 97168 of rec.radio.amateur.homebrew Message-ID: <4444EA45.304C5072@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: Date: Tue, 18 Apr 2006 13:32:29 GMT Mr Fed UP wrote: > > Heh heh dont forget the asprin and $50 for the headache and one > tool you'll always have to go get for each job. And a 6" or 8" > knuckle buistin adjustable wrench. LOL Don't forget a 4" pipe wrench for those tight spots! It has been a real life saver to remove broken studs and broken pieces of bolts. I have one made by Rigid. BTW, you won't bust your knuckles if you buy a real wrench. 8" is too short to get a good grip on things. I have a 12" and a 14" "New Britain" adjustable, along with a 4" Xcelite in my electronics tools. The only tools I usually have to buy these days are new ones to replace what walks away. :( -- 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: 97169 of rec.radio.amateur.homebrew From: John Wilkinson Subject: shielded multiway connector Date: Tue, 18 Apr 2006 14:39:43 +0100 Message-ID: Hi, I am using an LMS485 chips to send a differential 1MHz clock to multiple PLL's via twisted screened cable. Does anyone know of a screened small 2 way connector I could use on my PCB for this? Thanks, John. Article: 97170 of rec.radio.amateur.homebrew From: Silfax Subject: Re: The Perfect Gift: A Tool Box References: Message-ID: Date: Tue, 18 Apr 2006 13:56:02 GMT On 2006-04-17, Fred McKenzie wrote: > > A plastic or metal box such as the 13² plastic box from Walmart or the 14² > plastic box from Lowes. The box should have a secure latch that wonıt > come open when picked up. > 6" and 12" adjustable wench 12' tape measure (25' would be better) mechanical pencil, extra leads and a small notepad Article: 97171 of rec.radio.amateur.homebrew From: Silfax Subject: Re: The Perfect Gift: A Tool Box References: Message-ID: Date: Tue, 18 Apr 2006 13:58:06 GMT On 2006-04-18, Silfax wrote: > > 6" and 12" adjustable wench oops I meant wrench, although a flexible wench might not be a bad idea either (but she should be bigger than 12 inches....) Article: 97172 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Buildig block IF amplifiers? Message-ID: References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> Date: Tue, 18 Apr 2006 15:21:47 GMT On 18 Apr 2006 07:45:08 -0700, "Tim Shoppa" wrote: >clifto wrote: >> Has anyone played with any of the new high-bandwidth op amps in IF >> amplifier circuits? I've got an idea I want to experiment with, and >> not a whole lot of analog design ability (though I do better with >> building blocks than with compensating discretes), and now that >> GBw products are cheap above 1 MHz it might look practical to >> pursue. I have no standards for comparison since I know nothing >> about parameters like noise figures and the like in standard >> discrete circuits. > >GBw products above 1MHz have been around for a long time in op amps, if >you don't mind dropping the bucks then you can even get GHz numbers. >There's very little stopping anyone from using even the old >high-bandwidth op amps in IF's. But there's not much need to. > >In IF strips for FM receivers, most op-amps do really bad things when >they hit their limiting amplitudes. Google for "phase reversal" with >"op amp". > >"Straight" op-amps are not easily amenable to AGC action, but I've done >some playing around with for example LED/CdS optocouplers as very >linear controllable-loss blocks for AGC action and they work fine up >through the low MHz. Above a few MHz I think capacitance across the CdS >photocell gives too much leakage in typical receiver use, although if >you only want a limited amount of AGC I think you're good to go. > >It is MOST interesting to use chips like AD603's in IF's if you want >AGC action. Many many app notes and construction articles on the web >will show you examples of use. > >Are you perhaps really talking about RC active filters to replace >crystal or mechanical IF filters? I have always been VERY PESSIMISTIC >about this, usually even few percent tolerance capacitors (not cheap) >cause your passband/ultimate rejection to be way way worse than what >you expect. Different filter topologies have different tradeoffs, but >RC active filters when you want the Q to be >100 and want even mediocre >ultimate rejection are economically unfeasible in every analysis I've >done. > >Tim. Tim, Same here. though at one point I did try a 2 quadrant multiplier for AGC using opamps and while it worked the realization was you needed a lot of parts and it was not quiet. It's the job then of AGC to prevent hitting the rails. What really seperates a good IF from a poor one is behavour under AGC. Often the detector for the AGC system is a weaker link. I've designed enough that exotica is often less an answer then just plain good design with reasonable parts. The cheap item is gain, controlling bandwidth, noise and gain are harder. Allison Article: 97173 of rec.radio.amateur.homebrew From: jakdedert Subject: Re: The Perfect Gift: A Tool Box References: <4444EA45.304C5072@earthlink.net> Message-ID: Date: Tue, 18 Apr 2006 10:48:15 -0500 Michael A. Terrell wrote: > Mr Fed UP wrote: >> Heh heh dont forget the asprin and $50 for the headache and one >> tool you'll always have to go get for each job. And a 6" or 8" >> knuckle buistin adjustable wrench. LOL > > > Don't forget a 4" pipe wrench for those tight spots! It has been a > real life saver to remove broken studs and broken pieces of bolts. I > have one made by Rigid. > > BTW, you won't bust your knuckles if you buy a real wrench. 8" is too > short to get a good grip on things. I have a 12" and a 14" "New Britain" > adjustable, along with a 4" Xcelite in my electronics tools. > A common problem is to turn the adjustable wrench around the *wrong way*! I've had people argue that there is no wrong orientation for the common 'C' (Crescent) wrench, but there most certainly is. Do it wrong and you'll be fine 75% of the time; but that one time when you need it to really bite--and you do it wrong--*you* are the one who gets bitten. > The only tools I usually have to buy these days are new ones to > replace what walks away. :( Boy Howdy! I recently moved my office/shop and salvaged the buildings on the property at the same time. I'm still trying to find all my tools.... jak > Article: 97174 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: The Perfect Gift: A Tool Box Date: Tue, 18 Apr 2006 08:50:07 -0700 Message-ID: <124a2mmbs6uflca@corp.supernews.com> References: <1248ta74cr2pm3e@corp.supernews.com> Roy, "Roy Lewallen" wrote in message news:1248ta74cr2pm3e@corp.supernews.com... > Tektronix used Pozidriv screws exclusively for many years, until they > converted over to Torx. A standard Phillips bit fits poorly in a Pozidriv > screw, making it really easy to chew up the screw with this combination. How well does it work the other way around -- using Pozidriv screwdrivers on "regular old" Phillips-head screws? Article: 97175 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: Buildig block IF amplifiers? Date: Tue, 18 Apr 2006 08:57:44 -0700 Message-ID: <124a34vfq7l3ie3@corp.supernews.com> References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> "Tim Shoppa" wrote in message news:1145371508.131596.99210@i40g2000cwc.googlegroups.com... > Are you perhaps really talking about RC active filters to replace > crystal or mechanical IF filters? I have always been VERY PESSIMISTIC > about this, usually even few percent tolerance capacitors (not cheap) > cause your passband/ultimate rejection to be way way worse than what > you expect. I'm not as pessimistic as you, but I share your disappointment to some extent. However, if a filter doesn't need to be in "active duty" 100% of the time, having it self-calibrate seems potentially viable, at least for lower order filters. > Different filter topologies have different tradeoffs, but > RC active filters when you want the Q to be >100 and want even mediocre > ultimate rejection are economically unfeasible in every analysis I've > done. I'm usually after active filters for the sake of space, and consider Q>100 difficult to achieve at HF with any physically small design. I do enjoy the occasional posts from people whose SPICE simulations show ultimate rejections in the couple hundred dB ballpark. :-) ---Joel Article: 97176 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA:MOUSER 24VCT 1 A + OTHER STUFF Message-ID: Date: Tue, 18 Apr 2006 17:12:56 GMT NOS MOUSER 24VCT AT 1AMP XFMRS LESS THAN 9 HRS LEFT: + more tubes, fixed vac caps,+ vac relays and other stuff; see at: http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy Tnx , heytubeguy Article: 97177 of rec.radio.amateur.homebrew Message-ID: <4445212A.7878413@earthlink.net> From: "Michael A. Terrell" Subject: Re: Buildig block IF amplifiers? References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> Date: Tue, 18 Apr 2006 17:26:43 GMT Tim Shoppa wrote: > > clifto wrote: > > Has anyone played with any of the new high-bandwidth op amps in IF > > amplifier circuits? I've got an idea I want to experiment with, and > > not a whole lot of analog design ability (though I do better with > > building blocks than with compensating discretes), and now that > > GBw products are cheap above 1 MHz it might look practical to > > pursue. I have no standards for comparison since I know nothing > > about parameters like noise figures and the like in standard > > discrete circuits. > > GBw products above 1MHz have been around for a long time in op amps, if > you don't mind dropping the bucks then you can even get GHz numbers. > There's very little stopping anyone from using even the old > high-bandwidth op amps in IF's. But there's not much need to. > > In IF strips for FM receivers, most op-amps do really bad things when > they hit their limiting amplitudes. Google for "phase reversal" with > "op amp". > > "Straight" op-amps are not easily amenable to AGC action, but I've done > some playing around with for example LED/CdS optocouplers as very > linear controllable-loss blocks for AGC action and they work fine up > through the low MHz. Above a few MHz I think capacitance across the CdS > photocell gives too much leakage in typical receiver use, although if > you only want a limited amount of AGC I think you're good to go. > > It is MOST interesting to use chips like AD603's in IF's if you want > AGC action. Many many app notes and construction articles on the web > will show you examples of use. > > Are you perhaps really talking about RC active filters to replace > crystal or mechanical IF filters? I have always been VERY PESSIMISTIC > about this, usually even few percent tolerance capacitors (not cheap) > cause your passband/ultimate rejection to be way way worse than what > you expect. Different filter topologies have different tradeoffs, but > RC active filters when you want the Q to be >100 and want even mediocre > ultimate rejection are economically unfeasible in every analysis I've > done. > > Tim. The engineers at my last job liked the Mini Circuits ERA and similar monolithic amps. They also liked to do most of the AGC on the front end rather than at the IF. This sometimes included an electronic attenuator to drop the gain by 20 dB to prevent overloading a critical stage. The customers liked the way they worked, they ordered plenty of them at $20,000 USD each. -- 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: 97178 of rec.radio.amateur.homebrew From: "Bill Turner" Subject: Re: The Perfect Gift: A Tool Box References: <1248ta74cr2pm3e@corp.supernews.com> Message-ID: <44452ce3_2@newsfeed.slurp.net> Date: 18 Apr 2006 13:16:03 -0500 ORIGINAL MESSAGE: Roy Lewallen wrote: > Tektronix used Pozidriv screws exclusively for many years, until they > converted over to Torx. A standard Phillips bit fits poorly in a > Pozidriv screw, making it really easy to chew up the screw with this > combination. Any decent toolbox should include some Pozidriv drivers > or bits. *********** REPLY SEPARATOR *********** The flutes on a Phillips bit are tapered; on a Pozidrive they are parallel. In many cases you can use either bit on the other, but if available, use the correct one. A Phillips bit can "lever" itself out due to the taper, where a Pozidrive will not. Bill, W6WRT ex Tektronix employee Article: 97179 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: The Perfect Gift: A Tool Box Date: Tue, 18 Apr 2006 11:53:39 -0700 Message-ID: <124addnke4t1qcd@corp.supernews.com> References: <1248ta74cr2pm3e@corp.supernews.com> <124a2mmbs6uflca@corp.supernews.com> Joel Kolstad wrote: > Roy, > > "Roy Lewallen" wrote in message > news:1248ta74cr2pm3e@corp.supernews.com... >> Tektronix used Pozidriv screws exclusively for many years, until they >> converted over to Torx. A standard Phillips bit fits poorly in a Pozidriv >> screw, making it really easy to chew up the screw with this combination. > > How well does it work the other way around -- using Pozidriv screwdrivers on > "regular old" Phillips-head screws? In my experience, it works better than using a Phillips driver on a Pozidriv screw. But it still doesn't fit really well. Roy Lewallen Article: 97180 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Fading signals Date: Tue, 18 Apr 2006 13:45:13 -0500 Message-ID: References: "clifto" wrote in message news:nnaeh3-r41.ln1@remote.clifto.com... > Has anyone gotten a good oscilloscope look at the type of signals > that distort by cancellation of part of the carrier, i.e. the > signals that synchronous detectors detect much better than other > types? I'm wondering about the characteristics that make these > signals so hard to understand when they "fade" into that condition. > > -- > All relevant people are pertinent. > All rude people are impertinent. > Therefore, no rude people are relevant. > -- Solomon W. Golomb Not sure just what you mean, but AM needs a carrier to work. In an envelope detector, the carrier is needed to have the correct waveform so that the audio can be extracted. If there is no carrier, or too little, the waveform is not what is needed for the detector to work. Listen on a sideband receiver and you don't need the carrier and only the fade occurs with no distortion. Just look at the waveforms for AM and Single sideband in tutorials which are all over the web and it is obvious. If the carrier goes down, you don't get that waveform. I couldn't find any good papers on the web showing the waveforms of AM and what happens as you reduce the carrier, but,... Here are some references that may help you. http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/RadCom/part9/page2.html http://www.radio-electronics.com/info/receivers/synchdet/sync_det.php http://www.radio-electronics.com/info/receivers/am_demod/diode_am_demod.php Compare the waveforms in those with what is here. See Fig 1 in this paper. http://www.scott-inc.com/ham/ssb_im.pdf It is what you see when the carrier fades compared to the classical waveform you see for AM above. Note the nice sine wave is gone. 73, Steve, K9DCI Article: 97181 of rec.radio.amateur.homebrew From: - exray - Subject: Re: Regen with spider web coils ? Date: Tue, 18 Apr 2006 17:40:40 -0400 Message-ID: <124an70425ttu93@corp.supernews.com> References: <1144845320.775026.160220@i39g2000cwa.googlegroups.com> <123pumofq556ic8@corp.supernews.com> <1144854845.624672.120090@z34g2000cwc.googlegroups.com> <123qfv7n2242bb9@corp.supernews.com> <1144869558.093043.141280@t31g2000cwb.googlegroups.com> <123ql49hqub4368@corp.supernews.com> <1145387883.001442.49690@u72g2000cwu.googlegroups.com> jvereker@wp.pl wrote: > OK, inductances are: > 30 uH, 7.5 uH, 1.9 uH. > Hi, Using a 90mm form with the centre as 50mm in diameter (like the ones in my previous photos) 2mm thickness with #22 wire you'll have 18 turns, 8-3/4 turns and 4 turns respectively. I wound my tickler on the outside...that makes it easier to adjust. Depends on your circuit but I'd guess maybe 4, 2 and 1 would be in the ballpark. Let us know how it turns out. GL, Bill Article: 97182 of rec.radio.amateur.homebrew From: fmmck@aol.com (Fred McKenzie) Subject: Re: The Perfect Gift: A Tool Box Date: Tue, 18 Apr 2006 22:30:43 -0400 Message-ID: References: <1248ta74cr2pm3e@corp.supernews.com> In article <1248ta74cr2pm3e@corp.supernews.com>, Roy Lewallen wrote: > I'd consider looking for some other tool dealers to do business with. > Pozidriv (a registered trademark of Phillips Screw Co.) screws and > drivers are very common, sold by just about every tool company from > Snap-on through Stanley to Sears. OK Guys! I've done some more checking, and still can't find a store that sells Posidrive or Pozidrive. I have one lead to a specialty tool store across the state, but the local Ace, Sears and Lowes don't carry either the screws or the drivers. I can see where the Posidrive may be used in some electronic equipment, but all of the screws in the hinges in my house, as well as the screws holding the locks on the doors, are definitely Phillips. Are Posidrive screws used for those applications in other countries? I can see now that my original list should have stopped without the additional items. The purpose was to define a really BASIC set of tools for use around the home! Fred Article: 97183 of rec.radio.amateur.homebrew From: Alfred Green Subject: Re: Accurate voltage calibration References: Message-ID: Date: Tue, 18 Apr 2006 19:36:50 -0700 jack wrote: > Thaler has the best voltage references -- there was a design in one of the > rags (Nuts n Volts or QEX) a few years ago in which 3 Thaler references > were placed in parallel for a super reference. Email me privately if you > would like a copy. > > Also, get a copy of Linear Technology Application Note 86 "A Standards Lab > Grade 20 bit DAC with 0.1ppm/degC Drift" -- Jim Williams is the author -- > and make sure to read the appendices. Williams also did an ApNote with a > comprehensive history of voltage measurement techniques, but I forget the > application number. > > Thanks for the suggestion. I must admit to never having heard of of 'Thaler', but a quick search has thrown up some really interesting stuff. No online ordering, but an 800 number to find the distributors. I'll follow up on that. I'll get the LT AppNote. Thanks for the info. 73 Alf NU8I Article: 97184 of rec.radio.amateur.homebrew From: Alfred Green Subject: Re: Accurate voltage calibration References: <1145097545.334257.20180@e56g2000cwe.googlegroups.com> Message-ID: Date: Tue, 18 Apr 2006 19:50:43 -0700 clifto wrote: > Alfred Green wrote: > >>That was kind of what I was looking for. I really am prepared to pay a >>few bob for something that I can reliably use as a reference in my lab. > > > I'm no expert, but I wonder what you might be able to do with a > temperature-compensated design around a LMV431BI. > That looks like an interesting part, cheap enough and available. I'll give it a try! Article: 97185 of rec.radio.amateur.homebrew From: kb9rqz@markmorgan.net Subject: Re: Finding short duration interference? Date: Tue, 18 Apr 2006 22:57:54 -0400 Message-ID: References: <1249ghuscr3fneb@corp.supernews.com> On Tue, 18 Apr 2006 03:40:12 -0700, mike wrote: >What's a good method for finding short duration interference? > >My 440 repeater is plagued by an interfering signal that lasts a small >fraction of a second, just long enough to bring up the repeater, >and repeats randomly every 20 seconds or so. >Comes and goes...Seems to be dependent on outside temperature. >Sometimes sounds like there's hum on the signal. >First thought was that it was one of those oscillating Winegard >RV TV antennas, but it doesn't seem to drift around like they >typically do. > >I hooked the repeater antenna up to the spectrum analyzer, >but the duration is too short to get thru the filters at >the bandwidth required to get any sensitivity. > >I can hear it on the mobile. >I've driven around the neighborhood, but the duration is so short >that I've not been able to track it down. Strength seems to peak >at different places blocks apart...but it's hard to tell. > >I have some experience with a double duckey and started designing >a doppler system, but it occurs that the short duration signal >will be completely washed out by the Switched Cap Filter. Don't see >how I'm gonna get the low rep-rate signal past the noise. Filter >types that I know about ain't gonna work. > >Ideas? >Thanks, mike can you just duck the problem and use a PL tone Iknwo when we lived in sprinfeild it worked welll a 2 m repeater and another 440repeater in the general area that worked out well too _________________________________________ Usenet Zone Free Binaries Usenet Server More than 140,000 groups Unlimited download http://www.usenetzone.com to open account Article: 97186 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: The Perfect Gift: A Tool Box Date: Tue, 18 Apr 2006 20:37:26 -0700 Message-ID: <124bc3r5csvlp1b@corp.supernews.com> References: <1248ta74cr2pm3e@corp.supernews.com> Fred McKenzie wrote: > In article <1248ta74cr2pm3e@corp.supernews.com>, Roy Lewallen > wrote: > >> I'd consider looking for some other tool dealers to do business with. >> Pozidriv (a registered trademark of Phillips Screw Co.) screws and >> drivers are very common, sold by just about every tool company from >> Snap-on through Stanley to Sears. > > > OK Guys! I've done some more checking, and still can't find a store that > sells Posidrive or Pozidrive. I have one lead to a specialty tool store > across the state, but the local Ace, Sears and Lowes don't carry either > the screws or the drivers. There's sure no problem finding mail order sources: http://www.stanleytools.com/default.asp?TYPE=CATEGORY&CATEGORY=HT+PZDRV+AND+MULTI+SDRVRS http://www.vermontamerican.com/products/subcategorybrowse.htm?G=157721 http://buy1.snapon.com/catalog/search_keyword.asp?keyword=POZIDRIV http://www.aaronsscrewdrivers.com/PowerBits.htm http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00973645000&subcat=Screwdrivers > I can see where the Posidrive may be used in some electronic equipment, > but all of the screws in the hinges in my house, as well as the screws > holding the locks on the doors, are definitely Phillips. Are Posidrive > screws used for those applications in other countries? > > I can see now that my original list should have stopped without the > additional items. The purpose was to define a really BASIC set of tools > for use around the home! The real advantage of Pozidriv is in applications where something is mass produced with the screws put in by power drivers, so they're fairly common in manufactured goods. I was really directing my earlier comment that every toolbox should have some Posidriv bits or drivers to people doing any kind of work on electronic equipment or other kinds of manufactured goods. Posidriv tools probably wouldn't be of much use for most household repairs, so wouldn't be appropriate for a very basic household tool box. The same goes for Torx. You can identify Pozidriv screws by a ding in between the slots. There's a good picture at http://www.aaronsscrewdrivers.com/PowerBits.htm. Roy Lewallen, W7EL Article: 97187 of rec.radio.amateur.homebrew From: dplatt@radagast.org (Dave Platt) Subject: Re: The Perfect Gift: A Tool Box Date: Wed, 19 Apr 2006 04:07:00 -0000 Message-ID: <124bdr4idtfus73@corp.supernews.com> References: <1248ta74cr2pm3e@corp.supernews.com> In article , Fred McKenzie wrote: >OK Guys! I've done some more checking, and still can't find a store that >sells Posidrive or Pozidrive. I have one lead to a specialty tool store >across the state, but the local Ace, Sears and Lowes don't carry either >the screws or the drivers. I haven't seen complete Pozidrive drivers anywhere around here, but Orchard Supply (local hardware outlet) has Pozidrive bits in several sizes, which will go into the usual magnetic-hex-socket driver handles. In fact, just yesterday I glanced over their $2.99 "17 bits in a small carrying case" assortment by the cash register, and found that it contains 3 Phillips and 3 similarly-sized Pozidrive bits. -- 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!