Article: 97243 of rec.radio.amateur.homebrew From: Bill Turner Subject: Re: The Perfect Gift: A Tool Box Date: Mon, 24 Apr 2006 22:23:56 -0700 Message-ID: References: <444DA7D0.F4A35232@earthlink.net> ORIGINAL MESSAGE: On Tue, 25 Apr 2006 04:39:30 GMT, "Michael A. Terrell" wrote: >I've used surface grinders, drills, and a cutting torch to >remove them to make repairs. *********** REPLY SEPARATOR *********** Often a Dremel tool with a thin grinding wheel will allow you to make a slot and then use a regular screwdriver to remove it. Bill, W6WRT Article: 97244 of rec.radio.amateur.homebrew From: Bill Turner Subject: Re: The Perfect Gift: A Tool Box Date: Mon, 24 Apr 2006 22:43:02 -0700 Message-ID: References: <1248ta74cr2pm3e@corp.supernews.com> ORIGINAL MESSAGE: On Tue, 25 Apr 2006 01:32:43 -0400, "Michael Kennedy" wrote: >I've never seen anything with a posidrive screw in it.. They aren't used >very much in the USA or at least in Florida... *********** REPLY SEPARATOR *********** Tektronix used Pozidriv for many years in their scopes. Sometime after I left the company in 1986 I was told they changed to Torx. You can recognize a Pozidriv screw because it looks like a Phillips but has a fine line scribed between adjacent flutes. Bill, W6WRT Article: 97245 of rec.radio.amateur.homebrew Message-ID: <444DCA30.C51D69F2@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: <444DA7D0.F4A35232@earthlink.net> Date: Tue, 25 Apr 2006 07:06:11 GMT Bill Turner wrote: > > ORIGINAL MESSAGE: > > On Tue, 25 Apr 2006 04:39:30 GMT, "Michael A. Terrell" > wrote: > > >I've used surface grinders, drills, and a cutting torch to > >remove them to make repairs. > > *********** REPLY SEPARATOR *********** > > Often a Dremel tool with a thin grinding wheel will allow you to make > a slot and then use a regular screwdriver to remove it. > > Bill, W6WRT Yes, sometimes, or even a fine toothed blade in a hacksaw, but not when you are standing on top of a ladder and struggling to reach the crappy hardware. The moron who built my four car garage used 4" or longer Robertson screws everywhere, and most of the heads were puled below the surface before the #2 bit slipped and chewed up the head. I broke two crowbars removing a dangerous hanging rack he's built to hold plywood above one of the bays. Both were flimsy, and they hung low enough that you could bump your head on exposed screw points sticking an inch though the bottom 2*4 beams. I had to remove and replace a lot of lumber that split because of the way he screwed things up. -- 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: 97246 of rec.radio.amateur.homebrew Message-ID: <444DCA86.E2B7B7B1@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: <1248ta74cr2pm3e@corp.supernews.com> Date: Tue, 25 Apr 2006 07:07:37 GMT Michael Kennedy wrote: > > I've never seen anything with a posidrive screw in it.. They aren't used > very much in the USA or at least in Florida... I have yet to need a > posidrive screwdriver and I've taken all kinds of things apart in my life.. > I consider a good set of torx and allen wrenches a necessity along with a > set of sockets and wrenches and of course a small set of jewlers > screwdrivers and mini torx bits, hammers, saws, etc... > > The funny thing is I never knew what that weird looking phillips bit I had > was called until today. Microdyne and Lockheed-Martin both use it, although Microdyne has moved out of the area. -- 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: 97247 of rec.radio.amateur.homebrew From: " NI4L" Subject: Amp Supply AT 1-6 Tuned input board Dentron FA Message-ID: Date: Tue, 25 Apr 2006 05:42:01 -0400 This is a complete AT 1-6 Tuned input board and switch from the Amp Supply LK series Amplifiers. This will fit into the Dentrons also. Have schematics for this. If you have a Stock Amp Supply or Dentron amp this is what you need. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=9716726956&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1 Article: 97248 of rec.radio.amateur.homebrew From: "Tom Holden" References: <444DA7D0.F4A35232@earthlink.net> Subject: Re: The Perfect Gift: A Tool Box Message-ID: Date: Tue, 25 Apr 2006 07:34:04 -0400 "Michael A. Terrell" wrote in message news:444DA7D0.F4A35232@earthlink.net... > I despise Robertson screws, along with the "Clutch head" screws. > Every time I run into either of them, someone has put them in with a > worn bit that strips the head and makes them almost impossible to > remove. I've used surface grinders, drills, and a cutting torch to > remove them to make repairs. I generally replace them with hex head > screws and make sure that I always inspect the bit before I start a job. > -- Misdirected feelings - should be towards worn bits of all types that can mess up all types of screws. Don't blame the screw for the fault of the bit and the recklessness of the user. Among the three common wood screws here (slot, Phillips and Robertson), I'll take the Robbie anyday. The ability of the bit to retain the screw is a big advantage. Tom Article: 97249 of rec.radio.amateur.homebrew Message-ID: <444E4230.4F409285@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: <444DA7D0.F4A35232@earthlink.net> Date: Tue, 25 Apr 2006 15:38:10 GMT Tom Holden wrote: > > "Michael A. Terrell" wrote in message > news:444DA7D0.F4A35232@earthlink.net... > > I despise Robertson screws, along with the "Clutch head" screws. > > Every time I run into either of them, someone has put them in with a > > worn bit that strips the head and makes them almost impossible to > > remove. I've used surface grinders, drills, and a cutting torch to > > remove them to make repairs. I generally replace them with hex head > > screws and make sure that I always inspect the bit before I start a job. > > -- > > Misdirected feelings - should be towards worn bits of all types that can > mess up all types of screws. Don't blame the screw for the fault of the bit > and the recklessness of the user. Among the three common wood screws here > (slot, Phillips and Robertson), I'll take the Robbie anyday. The ability of > the bit to retain the screw is a big advantage. > > Tom You can have all of them. I'll keep using hex and torx head screws, thank you! ;-) -- 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: 97250 of rec.radio.amateur.homebrew From: Bill Turner Subject: Re: The Perfect Gift: A Tool Box Date: Tue, 25 Apr 2006 09:06:49 -0700 Message-ID: References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> ORIGINAL MESSAGE: On Tue, 25 Apr 2006 15:38:10 GMT, "Michael A. Terrell" wrote: > You can have all of them. I'll keep using hex and torx head screws, >thank you! ;-) *********** REPLY SEPARATOR *********** I kind of like the square drive myself. I wonder why it's not more popular? Is there an inherent deficiency I'm not aware of? Bill, W6WRT Article: 97251 of rec.radio.amateur.homebrew From: "Greg Neill" References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> Subject: Re: The Perfect Gift: A Tool Box Message-ID: Date: Tue, 25 Apr 2006 13:09:10 -0400 "Bill Turner" wrote in message news:t6is42hddvr5h0gkn7f376evpurmjo78bq@4ax.com... > > I kind of like the square drive myself. I wonder why it's not more > popular? Is there an inherent deficiency I'm not aware of? The Robertson drive screws are ubiquitous in Canada where they were first made (in 1908) and patented. They are less so in the U.S. due to the fact that, after one business fiasco with licensing the right to manufacture to a third party in England, Robertson refused to license it to any one else, including Ford in the U.S. Ford would not adopt any screw for its production lines for which it could not guarantee unbroken availability, despite the fact that the screw proved to save considerable time in the production of cars. So, they never really caught on there like they did in Canada. Article: 97252 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: The Perfect Gift: A Tool Box Date: Tue, 25 Apr 2006 11:58:21 -0700 Message-ID: <124ssafmjsel1da@corp.supernews.com> References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> Greg Neill wrote: > > The Robertson drive screws are ubiquitous in Canada where > they were first made (in 1908) and patented. They are less > so in the U.S. due to the fact that, after one business > fiasco with licensing the right to manufacture to a third > party in England, Robertson refused to license it to any > one else, including Ford in the U.S. Ford would not adopt > any screw for its production lines for which it could not > guarantee unbroken availability, despite the fact that the > screw proved to save considerable time in the production > of cars. So, they never really caught on there like they > did in Canada. > They're catching on. I recently had my deck surface replaced, and nearly all the screws are square drive. (The remainder are Torx.) It's the first use I've seen of them here. They're readily available now at Home Depot and, I assume, other DIY stores. Roy Lewallen, W7EL Article: 97253 of rec.radio.amateur.homebrew Message-ID: <444E8C8B.E96BA3D1@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> <124ssafmjsel1da@corp.supernews.com> Date: Tue, 25 Apr 2006 20:55:26 GMT Roy Lewallen wrote: > > Greg Neill wrote: > > > > The Robertson drive screws are ubiquitous in Canada where > > they were first made (in 1908) and patented. They are less > > so in the U.S. due to the fact that, after one business > > fiasco with licensing the right to manufacture to a third > > party in England, Robertson refused to license it to any > > one else, including Ford in the U.S. Ford would not adopt > > any screw for its production lines for which it could not > > guarantee unbroken availability, despite the fact that the > > screw proved to save considerable time in the production > > of cars. So, they never really caught on there like they > > did in Canada. > > > > They're catching on. I recently had my deck surface replaced, and nearly > all the screws are square drive. (The remainder are Torx.) It's the > first use I've seen of them here. They're readily available now at Home > Depot and, I assume, other DIY stores. > > Roy Lewallen, W7EL They have been used in mobile homes for years in the US. I can buy them bulk at several local building surplus stores. There are several mobile home manufacturers in the area that dump a lot of leftover or damaged items. -- 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: 97254 of rec.radio.amateur.homebrew From: "Steve N." Subject: Re: Class C engineering question Date: Tue, 25 Apr 2006 15:46:55 -0500 Message-ID: References: <49X2g.63477$F_3.25444@newssvr29.news.prodigy.net> A couple of comments not covered by others.... ***** "Mont" wrote in message news:49X2g.63477$F_3.25444@newssvr29.news.prodigy.net... > Following is a note I received from a friend who earnestly believes that a > Class C plate modulated final requires approximately 200% (rather than 50%) > of the final power input to achieve 100% modulation. ...> Thanks, Mont - K0YCN > ------------------------------------------- > Mont, ... > My goal is to be capable of 130% positive peak modulation with 375 watts of > carrier output. ****** WHY?. What could be the possible benefit (thinking on terms of dB)? This is what, 2 dB more power in the sidebands...? This is 69% more power in the sidebands and 2dB is 56% more... > The Eimac 4-400...3000 volts...630 watts high level plate modulated carrier output. So, 630 watts X 4 = 2520 watts pep capability. ***** PEP is a red herring here. I could be wrong because of the contorted reasoning, but I believe he is confusing Peak power and PEP, but I can't be sure 'cuz I don't completely understand what he is trying to reason out. Peak Power is Vpk x Ipk PEP is V(rms at the peak) x I(rms at the peak) > ...375 watts X 4 X 1.30 = 1950 watts pos. peak. > Dividing that by 2 = 975 watts of peak audio output required... **** This appears to be a location for a logic fault. > The 4-125 typical operation indicates 330 watts of AB1 is available.... *** Noted for later. > The negative vs. positive peaks will be controlled by a broadcast quality > Innovonics AM asymmetrical compressor limiter which I am currently using in > the shack. *** This may be a separate issue, but doesn't this suggest that the modulator AND transformer must have the capability of handling the distorted waveform from this "asymmetrical compressor " such that the low frequency response extends low enough to get this extra plate voltage turing the positive peaks? > ... a 375 watt transmitter requires 187.5 watts of audio for > 100% modulation. So, a 4-125, with 330 watts of capability, should be more > than what is needed. *** No argument here... > In practical terms this is very misleading. *** paraphrased = " _I_ can't get _my_ circuit to work." > That is > why I been beating a dead horse for three years while two broadcast > engineers could not explain why I could barely attain near 100 modulation. > Little did I know that I was driving the pants of the poor 4-125's while > trying! *** Are the RF amp and modulator operating properly in the first place? *** Does he have the proper modulation transformer? *** Is he even using a modulation transformer? *** Is he confused between Peak power and PEP? 73, Steve, K9DCI > > Hence, I ordered a custom built filament xfmr that will power two 4-400 > modulators. Hope to have all that working in about two weeks. > > 73, > > Article: 97255 of rec.radio.amateur.homebrew From: "Steve N." Subject: Re: Feedback! Date: Tue, 25 Apr 2006 16:13:20 -0500 Message-ID: References: Pay attention to the placement of speakers. For one, don't try to use mics in front of speakers. The talker needs to have a zone and loud-speakers should not "talk" to that zone. People near the talker don't need to have loud-speakers to hear him/her, so if there are some, disconnect them. They should also "point" where the sound is needed, not oriented because the mounting is easy. You have to walk around and see where the loud-speakers are needed and have them there, but not everywhere. I obviously don't know if this is the case for you, but churches tend to have PA systems thrown at them rather than designed. You can "notch" the preferred frequency, for a few db of feedback margin, with an equalizer. However, when you notch the primary frequency, the next pops up a few dB down and you can keep chasing them until you have reduced the gain all thougth the spectrum. Plus, just move a foot or two and the path changes and the preferred frequency changes. I am unfamiliar with DSP feedback eliminators, but the job should be easier if you start at the source (of speaker / mic proximity) 73, Steve, K9DCI "James Thompson" wrote in message news:a5c67$444c2f44$438c8615$26880@ALLTEL.NET... > Has anyone got a good but cheap circuit to eliminate or surpress feedback. > Im making my son some low power fm mikes to use in his church, but they get > feedback real easy. Is there a simple notch filter per say that I can add > the the mike section of this. My pcb is only 1.5 by 2" right now. Thanks. > > Article: 97256 of rec.radio.amateur.homebrew From: biascomms Subject: Re: Feedback! References: Message-ID: <3Yx3g.59668$wl.5610@text.news.blueyonder.co.uk> Date: Tue, 25 Apr 2006 23:06:39 GMT James Thompson wrote: > Has anyone got a good but cheap circuit to eliminate or surpress feedback. > Im making my son some low power fm mikes to use in his church, but they > get feedback real easy. Is there a simple notch filter per say that I can > add > the the mike section of this. My pcb is only 1.5 by 2" right now. > Thanks. You can try an equaliser in the amplifier input feed, and try to notch out the worst feedback frequencies. This will work, but is quite a limited approach. The best method is to use a frequency shifter that moves the whole audio spectrum a few hertz up or down. Surrey Electronics here in England make such a device, and it's transparent in use - you can't hear it working, but feedback problems are almost entirely eliminated. http://reflectionseurope.com/surreyelectronics.html Chris -- Everything gets easier with practice, except getting up in the morning! Article: 97257 of rec.radio.amateur.homebrew From: Adrian Brentnall Subject: Re: Feedback! Date: Wed, 26 Apr 2006 08:17:12 +0100 Message-ID: <0s6u42lcslmukrgcg8chlkc7accgnbvluq@4ax.com> References: <3Yx3g.59668$wl.5610@text.news.blueyonder.co.uk> Hi On Tue, 25 Apr 2006 23:06:39 GMT, biascomms wrote: >James Thompson wrote: > >> Has anyone got a good but cheap circuit to eliminate or surpress feedback. >> Im making my son some low power fm mikes to use in his church, but they >> get feedback real easy. Is there a simple notch filter per say that I can >> add >> the the mike section of this. My pcb is only 1.5 by 2" right now. >> Thanks. > We had the same problem in our local Church. The 'system' involved a couple of bass guitar speakers hung on the wall, a guitar amp and a not-so-cheap omnidirectional mic at the lectern. The whole thing 'rang' like a bell at the slightest provovation. The Church is in a smallish room - probably 30ft x 50ft - with a low ceiling - and partly divided half-way by a couple of stub walls - which made it very hard for people at the back of the Church to hear wht was being said, unless the speakers at the front of the church were turned up loud enough that you got feedback... The solution was to replace the lot ! - but as a lot of it was homebrewed it didn't cost a fortune. The lectern mics were replaced by a pair of electret boundary mics with a cardiod response (didn't pick up sound from the direciton of the speakers. The giant bass speakers were replaced by two pairs of decent 2nd-hand hi-fi speakers - one pair near the front of the Church and the other pair at the stub walls, facing backwards. The amp was replaced with a custom unit, containing three (mono) 40Watt IC amp modules - one for the front speakers, one for the back speakers and the third one for future use to drive an inductive hearing aid loop. Volume is independantly controllable between the front and rear speakers. This, of course, is a specific solution for our specific situation. What you probably need to do is start with a simple plan of your Church - showing the areas where mics are needed, and where you can put speakers. If possible, you'll find that multiple, independantly-controllable speakers will allow you to keep the sound level high enough for intelligibilty without getting feedback - you might find that you only need amplification 'at the back' of the Church.... Look closely at mics - the closer and more directional the better - may even be worthwhile using radio mics, if your people can be trained to use them. The notch filter will work - but it's only a 'band-aid' solution - get the accoustic design right and you won't need one ! Hope this helps Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply Article: 97258 of rec.radio.amateur.homebrew From: Adrian Brentnall Subject: Re: Feedback! Date: Wed, 26 Apr 2006 08:21:04 +0100 Message-ID: References: <3Yx3g.59668$wl.5610@text.news.blueyonder.co.uk> Hi again James Should have read your original post more carefully - sorry ! On Tue, 25 Apr 2006 23:06:39 GMT, biascomms wrote: >James Thompson wrote: > >> Has anyone got a good but cheap circuit to eliminate or surpress feedback. >> Im making my son some low power fm mikes to use in his church, but they >> get feedback real easy. Is there a simple notch filter per say that I can >> add >> the the mike section of this. My pcb is only 1.5 by 2" right now. >> Thanks. I guess that you could build a speicific notch into the mic pcb - but that'll only work if the feedback is at one specific (resonant) frequency. I think the best filtering systems are 'adaptive' - in that they can spot feedback happening and can drop a tunable notch on top of it in real time. Complicated though - and tends to be done at the amp, rather than at the mic. All the stuff in the other post applies though - look at the system first...... Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply Article: 97259 of rec.radio.amateur.homebrew Subject: Re: Microwave Projects? From: JJ References: <4cc36$4447a312$d135c4af$31881@MDI.CA> <1145727069.586990.95580@j33g2000cwa.googlegroups.com> Message-ID: <647bb$444fa79d$d135c4af$23197@MDI.CA> Date: Wed, 26 Apr 2006 13:02:21 -0400 skavanagh72nospam@yahoo.ca wrote in news:1145727069.586990.95580 @j33g2000cwa.googlegroups.com: > What do you mean by simple receivers ? What are you trying to receive, > with what stability and sensitivity ? Amateurs have traditionally used > crystal-controlled downconverters in front of lower frequency > receivers, but this is generally suited only for receiving small > segments of spectrum and doesn't usually have a very small parts count. > The local oscillator usually involves several multiplier stages and > tunable filters. The performance can be very good though. Something that can be built with 1 chip just to experiment for now. >From what I read, regular fiberglass boards don't work well above 1 GHz. Where do you get teflon boards? JJ Article: 97260 of rec.radio.amateur.homebrew Subject: Re: Microwave Projects? From: JJ References: <4cc36$4447a312$d135c4af$31881@MDI.CA> <9Fz2g.6699$kg.5945@news02.roc.ny> <1145899710.712380.229440@j33g2000cwa.googlegroups.com> Message-ID: <153d6$444fa813$d135c4af$23197@MDI.CA> Date: Wed, 26 Apr 2006 13:04:19 -0400 "tucker@conninc.com" wrote in news:1145899710.712380.229440@j33g2000cwa.googlegroups.com: > Seems you could take advantage of all the old Ku & C band > receivers,lnbs and other big dish stuff that people are throwing away, > i > remember the reciever tunes a 950-1400 mhz input span or somewhere > close, from the lnb. Should be alot easier to convert one of > these yardsale items than start from scratch. Ive got a bunch of these > setting around & wanted to put one on the 33cm 902-928mhz > amateur tv band, but the satellite starts alittle higher than that so i > put it on hold for now. Cool, how much are these cheap receivers? Can you use them for a radio telescope @1420MHz? These would need to recieve AM mode. JJ Article: 97261 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: Microwave Projects? Date: Wed, 26 Apr 2006 10:27:49 -0700 Message-ID: <124vbcmg1q6u305@corp.supernews.com> References: <4cc36$4447a312$d135c4af$31881@MDI.CA> <1145727069.586990.95580@j33g2000cwa.googlegroups.com> <647bb$444fa79d$d135c4af$23197@MDI.CA> "JJ" wrote in message news:647bb$444fa79d$d135c4af$23197@MDI.CA... > skavanagh72nospam@yahoo.ca wrote in news:1145727069.586990.95580 > From what I read, regular fiberglass boards don't work well above 1 GHz. That's a bit of an overgeneralization. We routinely use "generic" FR-4 to 3GHz, and you'll find that many wireless routers at 2.4GHz do as well. As long as the paths are relatively short and you're just using the board to get a signal from point A to point B, it works pretty well. The folks who suggest you use Teflon or other high-quality board materials are probably thinking of building distributed circuits on it -- stuff like filters, where the board's loss (its Q) significantly impact how good your filter's response is. (Building something like a bandpass WiFi filter -- ~25MHz wide at ~2.45GHz -- on FR-4 using coupled lines is probably not such a hot idea -- this would be a good test case to simulate.) > Where do you get teflon boards? All the decent-sized board houses (e.g., Advanced Circuits, DDI, etc.) have low-loss board materials available. Nelco (http://www.parknelco.com/) and Rogers (http://www.rogers-corp.com/acm/index.htm) are two of the big players here. We have many boards done in Nelco 4000-13, which is a "mid-loss" material... only somewhat better than FR-4 when it comes to absolute loss, but considerably better when it comes to the specs not drifting over process, temperature, etc., all at a relatively small pricing premium. If you can afford it, by all means, get low-loss boards. However, in many cases in the low-GHz area you end up with more loss from items such as coax cable, connectors, impedances mismatches, etc. than the PCB material itself. ---Joel Kolstad Article: 97262 of rec.radio.amateur.homebrew Date: Thu, 27 Apr 2006 21:01:03 +0800 From: Richard Hosking Subject: Re: HB VHF low-pass filter References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> Message-ID: <4450c090$0$30749$5a62ac22@per-qv1-newsreader-01.iinet.net.au> Is it a single pager? I once watched the local pager band with a spectrum analyser, and there were at least a dozen pagers coming on and off at different times and on different frequencies, the lowest of which was below 149MHz. (This is in Australia) Several of them actually produced IM products between them that were *not* from the spec an front end. I surmise that these are actually produced locally. Apparently transmitter output stages can produce these when there are antennas located close to each other (within a few metres) on the same tower. Others have proposed a stub configuration - you may have to consider beefing up the front end for better strong signal handling as well if there are several signals. Richard paul@burridge8333.fsbusiness.co.uk wrote: > Hi gang, > > And old chum of mine suffers badly from pager interference when he's > trying to listen on the 2m band. The interference is strong to him > (S9+) and takes out all his reception, despite the fact that it's quite > a way up-band at 153Mhz. > I've been looking into designing a filter for him to cut off by 153Mhz > to better than -20db but it turns out to be rather more tricky than I'd > imagined. Even with a seven element butterworth configuration, the > difference between the 146Mhz (wanted) and the 153Mhz (unwanted is an > insignificant 6db or so. I'm just not getting enough roll-off and need > something much sharper. Worse still, the roll-off I'm seeing is on a > computer simulation of the filter with ideal components and would no > doubt be even worse with real-world Ls and Cs. Any suggestions as to > how to tackle the problem, guys? > Thanks, > P. > Article: 97263 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Regen Question Message-ID: <0dn152l7mtg3mj5n91ukaqm31ehn8jmj3t@4ax.com> References: <1146097667.588709.301120@v46g2000cwv.googlegroups.com> <1146126829.180068.76090@v46g2000cwv.googlegroups.com> <1146136445.610283.93380@i39g2000cwa.googlegroups.com> Date: Thu, 27 Apr 2006 15:12:21 GMT On 27 Apr 2006 04:14:05 -0700, dconley@lawfacts.com wrote: >Hi Mark, > >The resistor is definetly 6 Mohm, but you bring up an interesting point >about moisture. > >I have noticed that the set seems to fade out more during rainy or high >humidity days. I didn't even want to mention it because it sounded >silly, but I did wonder if humidity might be a factor. > >On some clear, dry days, I have not had any trouble at all. So, maybe >you have something there. > >I will carefully go back over the items you mentioned and maybe replace >all of the caps in the circuit. Replacing tubes hasn't made a >difference. Thanks. If anything the caps are least suspect as they are storing a charge where poor caps are leaky and would tend to not store a charge. I'd make sure the path from the grid to ground (one or the other side of the filiment) is a valid one. Sounds like the grid is floating (ungrounded). Also for Regens I've made I've always used a ceramic socket or insured the socket used was of the highest insulation quality. When you working with megohms a leakage path can be very sneaky. Flux residue on the socket or possible other places can become conductive and some absorb moisture well. Acetone, Isopropnal are good solvents from removing solder flux. *** Use caution as they are flamable.*** If built on wood, the rule was to bake (at under 200F) for a for several hours to a day till very dry and then varnish to insure the wood cannot absorb water as easily. Some thoughts, Allison Article: 97264 of rec.radio.amateur.homebrew From: "Brian Murrey" Subject: Transistor Deal Message-ID: Date: Thu, 27 Apr 2006 18:52:14 GMT I just came into possession of several thousand brand new Motorola brand PN2222A transistors in the TO-92 package. So I have them 100 for $7.00 including shipping in the USA. These are new (old stock), unused parts, still on the paper tape they were born with. The part is clearly labeled and is genuine Motorola goods. Order Item: PN2222 - Motorola Send your order payable to: Brian Murrey 47 Grassy Drive New Whiteland IN 46184 or Paypal to orders@hamradparts.com -- ========================================= Radio Amateurs - Fill your junk box, from my junkbox! http://www.hamradparts.com 73 de KB9BVN ========================================= Article: 97265 of rec.radio.amateur.homebrew From: "amdx" Subject: Test Date: Thu, 27 Apr 2006 14:43:27 -0500 Message-ID: Yes, I did post to a test group and it worked! But my last four posts here didn't show up. Sorry (maybe) Mike Article: 97266 of rec.radio.amateur.homebrew From: "amdx" Subject: Size of pcb for pin diode switch? Date: Thu, 27 Apr 2006 15:34:16 -0500 Message-ID: Hi All, I'm looking at the pcb on page 8 of the following; http://www.avagotech.com/pc/downloadDocument.do?id=3369 (It is an HP application note #1049) The way I figure it the pcb is 4" x 4" and the in/out and bias traces are .125" wide, necking down to .050". The vias compute to .170". Does any of this make sense for a surface mount pcb with so few parts? Mike Article: 97267 of rec.radio.amateur.homebrew Subject: Re: Microwave Projects? From: JJ References: <4cc36$4447a312$d135c4af$31881@MDI.CA> <1146140523.697972.318490@u72g2000cwu.googlegroups.com> Message-ID: <6082f$445136ed$d135c4af$8000@MDI.CA> Date: Thu, 27 Apr 2006 17:26:05 -0400 "Saandy , 4Z5KS" wrote in news:1146140523.697972.318490@u72g2000cwu.googlegroups.com: > one of the most widespread is is the 1N5711. I used them a lot. one of > their best features, besides the the 70 Volts reverse operating voltage > is that they are so uniform that i never had to select among them to > get a matched pair. > Saandy 4Z5KS > What is the maximum freq. for the 1N5711? I like something that works to 2.4GHz at least. JJ Article: 97268 of rec.radio.amateur.homebrew From: "stargatesg1" Subject: Plastic Antenna Insulators Message-ID: Date: Thu, 27 Apr 2006 22:39:22 GMT Anyone ever try using plastic drywall anchors for yagi antenna insulators? I'm wondering how they will hold up to UV and the weather in general. Thanks, RoD Article: 97269 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: Checkin' out dummy loads with a VNA... Date: Thu, 27 Apr 2006 16:04:24 -0700 Message-ID: <1252jfpmve2o79a@corp.supernews.com> References: <1146178584.921966.197090@y43g2000cwc.googlegroups.com> wrote in message news:1146178584.921966.197090@y43g2000cwc.googlegroups.com... > Problem is, all the documentation I have for my VNA shows devices to be > tested having *two* connectors (an 'in' and an 'out' if you will) like > filters for example. I can only connect to the *one* connection that > dummy loads typically have, since it'a a termination device rather than > a through one like a filter or attenuator. Does that mean I can't > analyse its > characteristics? Tell your VNA you want to measure S11; it won't even touch the second port (feel free to hook it up to a high-gain antenna and point it at the nearest cell phone tower in your neighborhood...) Unless your VNA is 20+ years old, it'll be happy to display the S11 measurement in the form of a Smith chart, real/imaginary impedances, VSWR, etc... Article: 97270 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Checkin' out dummy loads with a VNA... References: <1146178584.921966.197090@y43g2000cwc.googlegroups.com> Message-ID: Date: Thu, 27 Apr 2006 23:19:03 GMT Hello Paul, > > I'd like to see what this new dummy load I just bought on e-bay looks > like under test at its purported frequency limit of one Gig. > Problem is, all the documentation I have for my VNA shows devices to be > > tested having *two* connectors (an 'in' and an 'out' if you will) like > filters for example. I can only connect to the *one* connection that > dummy loads typically have, since it'a a termination device rather than > > a through one like a filter or attenuator. Does that mean I can't > analyse its > characteristics? Or is there a work around/special cable configuration > that would solve > this problem? A quick and dirty one would be to use a resistor from VNA-out to dummy load, then another from dummy load to VNA-in. 50 ohms or less. With next to nothing reactive, of course. All nicely RF fashioned, chip resistors maybe. It's not going to be matched but you can have the analyzer do the math to calculate out the dummy load. Mind the power limits. Sometimes I do this with an HP resistive splitter when the impedance analyzer is down (like it is right now, again....%*&#!!). Regards, Joerg http://www.analogconsultants.com Article: 97271 of rec.radio.amateur.homebrew From: biascomms Subject: Re: Plastic Antenna Insulators References: Message-ID: Date: Fri, 28 Apr 2006 05:54:38 GMT stargatesg1 wrote: > Anyone ever try using plastic drywall anchors for yagi antenna insulators? > I'm wondering how they will hold up to UV and the weather in general. It depends on the plastic material - it's worth doing the microwave oven test before using it. I find that PVC that's OK in the microwave oven usually stands up to UV well. Bob -- Everything gets easier with practice, except getting up in the morning! Article: 97272 of rec.radio.amateur.homebrew From: "Bernard caron" Subject: test Message-ID: Date: Fri, 28 Apr 2006 09:30:04 GMT Article: 97273 of rec.radio.amateur.homebrew From: "amdx" References: <1146190452.983863.54720@v46g2000cwv.googlegroups.com> Subject: Re: Size of pcb for pin diode switch? Date: Fri, 28 Apr 2006 10:55:46 -0500 Message-ID: <3f0a$44523afb$45011502$495@KNOLOGY.NET> "K7ITM" wrote in message news:1146190452.983863.54720@v46g2000cwv.googlegroups.com... > It was probably just a convenient size...but FWIW, if I measure the > traces compared with the SOT-23 size (lead spacing, for example), I get > that the input/output traces are 0.054", plus or minus a bit. To be 50 > ohms on an FR-4 board, that must mean the distance to the ground plane > is about 1/32 inch (which seems quite reasonable), and the board would > be about 1.8" across. > > Cheers, > Tom > Hi Tom, Thanks for your info, I recomputed using the lead spacing and got about the same 1.8" as you say. My first computation used the info from the article that the diode spacing is 0.27" apart, this is how I got 4". I'm still not sure about the size, because using either computation I should get the same answer. You are correct on the 1/32" FR-4, it is somewhere in the article. If I make this circuit it will be a 75 ohm pcb for a cable tv switch. I'll need to look for a stripline calculator. Mike Article: 97274 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Checkin' out dummy loads with a VNA... References: <1146178584.921966.197090@y43g2000cwc.googlegroups.com> <1146188811.527595.197470@j73g2000cwa.googlegroups.com> <1146222971.004296.183710@i39g2000cwa.googlegroups.com> Message-ID: Date: Fri, 28 Apr 2006 17:21:46 GMT Hello Paul, > Okay guys, thanks. > Yes, as you've surmised, I'm only just beginning to get to grips with > this complex piece of kit and there is *much* to learn indeed. In my > defence, I have to say although I purchased this thing 5 months ago, > I've only now been able to assemble the ancilliary cables, loads, > splitters and whatnot to be able to check it out properly. All I could > do back in December was to switch it on and check for signs of life. > Now, however, things start to get rather more complicated ( but > hopefully stimulating, too). > Just curious, which VNA are you using? Tentec has a really nice one. Only goes to 100MHz but for around $700 it seems like a good deal. Some of my clients could have used these but unfortunately this VNA does not seem to have an industry-standard calibration scheme. Wish they did, then I could probably get rid of my heavy 4191 in the lab. Regards, Joerg http://www.analogconsultants.com Article: 97275 of rec.radio.amateur.homebrew From: Bill Turner Subject: Re: The Perfect Gift: A Tool Box Date: Fri, 28 Apr 2006 12:04:33 -0700 Message-ID: References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> <124ssafmjsel1da@corp.supernews.com> <444E8C8B.E96BA3D1@earthlink.net> ORIGINAL MESSAGE: On Tue, 25 Apr 2006 20:55:26 GMT, "Michael A. Terrell" wrote: > They have been used in mobile homes for years in the US. I can buy >them bulk at several local building surplus stores. There are several >mobile home manufacturers in the area that dump a lot of leftover or >damaged items. *********** REPLY SEPARATOR *********** I would think one advantage of square drive would be it is nearly impossible to strip the drive hole, unlike Phillips and especially hex (Allen). I think I'll scout around for some for my next building project in 6-32, 8-32 and 10-32. Who knows, might even try metric sizes. Bill, W6WRT Article: 97276 of rec.radio.amateur.homebrew From: Win Subject: Roller Inductor Squeak Date: Fri, 28 Apr 2006 15:15:10 -0500 Message-ID: What is a good conductive lub to use on roller indictors? The inductor in my tunert squeaks like an old door. Any other tips to keep that roller noise down? Win, w0lz Article: 97277 of rec.radio.amateur.homebrew Message-ID: <44528AB4.CFFE7F50@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> <124ssafmjsel1da@corp.supernews.com> <444E8C8B.E96BA3D1@earthlink.net> Date: Fri, 28 Apr 2006 21:38:00 GMT Bill Turner wrote: > > ORIGINAL MESSAGE: > > On Tue, 25 Apr 2006 20:55:26 GMT, "Michael A. Terrell" > wrote: > > > They have been used in mobile homes for years in the US. I can buy > >them bulk at several local building surplus stores. There are several > >mobile home manufacturers in the area that dump a lot of leftover or > >damaged items. > > *********** REPLY SEPARATOR *********** > > I would think one advantage of square drive would be it is nearly > impossible to strip the drive hole, unlike Phillips and especially hex > (Allen). I think I'll scout around for some for my next building > project in 6-32, 8-32 and 10-32. > > Who knows, might even try metric sizes. > > Bill, W6WRT I have never seen them with machine screw threads, only as wood screws. -- 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: 97278 of rec.radio.amateur.homebrew From: "Greg Neill" References: <444DA7D0.F4A35232@earthlink.net> <444E4230.4F409285@earthlink.net> <124ssafmjsel1da@corp.supernews.com> <444E8C8B.E96BA3D1@earthlink.net> <44528AB4.CFFE7F50@earthlink.net> Subject: Re: The Perfect Gift: A Tool Box Message-ID: Date: Fri, 28 Apr 2006 17:45:46 -0400 "Michael A. Terrell" wrote in message news:44528AB4.CFFE7F50@earthlink.net... > Bill Turner wrote: > > > > I would think one advantage of square drive would be it is nearly > > impossible to strip the drive hole, unlike Phillips and especially hex > > (Allen). I think I'll scout around for some for my next building > > project in 6-32, 8-32 and 10-32. > > > > Who knows, might even try metric sizes. > > > > Bill, W6WRT > > > > I have never seen them with machine screw threads, only as wood > screws. Ah, you poor deprived person! Got 'em aplenty up here in the Great White North! Article: 97279 of rec.radio.amateur.homebrew From: Dr. Anton T. Squeegee Subject: Re: Eavesdropping Video Receives 5 Stars Review Date: Fri, 28 Apr 2006 21:00:44 -0700 Message-ID: References: <1146238788.142978.81160@y43g2000cwc.googlegroups.com> In article <1146238788.142978.81160@y43g2000cwc.googlegroups.com>, ctaylor@pinpoint-productions.com (known to some as ctaylor@pinpoint- productions.com) scribed... > The newspapers and journals are full of information about warrantless > wiretapping and eavesdropping... And Usenet groups are obviously full of posts that are off-topic and irrelevant to the given subject of the group. Your drivel was an excellent example of such. *PLONK!* -- Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute (Known to some as Bruce Lane, KC7GR) http://www.bluefeathertech.com -- kyrrin a/t bluefeathertech d-o=t calm "Salvadore Dali's computer has surreal ports..." Article: 97280 of rec.radio.amateur.homebrew From: "Greg Neill" References: <1146323696.956339.201070@j73g2000cwa.googlegroups.com> <1146324280.967879.213460@e56g2000cwe.googlegroups.com> Subject: Re: 13.8V high current power supply Message-ID: Date: Sat, 29 Apr 2006 12:11:10 -0400 wrote in message news:1146324280.967879.213460@e56g2000cwe.googlegroups.com... > This is probably a stupid idea for some reason that's beyond me right > now, but how about losing the extra volts with a series of diode drops? > Provided the diodes were high forward current types with adequate heat > sinking. I know it wouldn't be as stable as a proper design, but would > it work well enough to run a mobile 100W rig? I think you'll end up with lousy regulation and a ripple problem. Article: 97281 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Regen Question Message-ID: <7k6752hdq16jsgo6e9ncopssl504mk3d28@4ax.com> References: <1146097667.588709.301120@v46g2000cwv.googlegroups.com> <1146302393.723665.188730@j33g2000cwa.googlegroups.com> <1146315252.554822.314130@g10g2000cwb.googlegroups.com> <1146317168.517145.160430@u72g2000cwu.googlegroups.com> Date: Sat, 29 Apr 2006 17:06:18 GMT On 29 Apr 2006 06:26:08 -0700, jvereker@wp.pl wrote: >My mistake, it's a triode, no screen grid. :) I'm not used to American >symbols, here in Europe we have easier sytem (EC-triode, ECC-double >triode, etc.). For me 1H2GT and 1T4T is the same tube ;) >What are the differences, advantages and disadvantages between methods >with a pot in plate circuit, screen grid circuit, throttle cap ? Apples and potatoes. Seriously screen grid valves(tubes) of the tetrode/pentatode flavor are different animals than triodes so applying comparison of regen throttle techniques across them is difficult to compare. However.. with that said. Throttle cap is usally the best as you can optimize the tube operating point and then only adjust the amount of feedback. Disadvantage is there is RF on the capacitor and that means careful layout and good mechanical mounting for stability. The other two vary the plate(anode) voltage and vary the screen grid voltage are similar as they both affect the gain of the tube by altering it's operating point. Disadvantage is that you may have to play more with the feedback winding (or tap) so that regeration occurs at the best point on the variable resistor or performance will suffer. Advantage, no RF on any of the wires to the resistor so placement and mounting is more flexible. Both can be made to work equally well with care. Allison Article: 97282 of rec.radio.amateur.homebrew From: "James Thompson" References: <1146323696.956339.201070@j73g2000cwa.googlegroups.com> Subject: Re: 13.8V high current power supply Date: Sat, 29 Apr 2006 13:22:10 -0400 Message-ID: <12b2e$4453a0c3$438c87aa$11884@ALLTEL.NET> wrote in message news:1146323696.956339.201070@j73g2000cwa.googlegroups.com... > Hi all, > > You may recall me mentioning I was thinking about adapting a 24V PSU > for use at 13.8V for powering up mobile HF rigs and stuff. I had some > spare time yesterday and took this thing to bits for a better look > inside. It turns out the mains transformer has several secondary > tapping points. I discontected the DC-stab/reg side of the supply > circuitry and reconnected the secondary tapping points to lower voltage > tappings. > Now I measure 16.8V after the transformer's output has been rectified > and applied across the *big* electrolytic. This is under no-load > conditions. Now, is that 3V enough 'headroom' to use up in regulation > and stabilisation for 13.8V final output if I throw the old 28V > reg/stab away and build something from scratch? There are 6 pass > transistors plus a driver (2n3055) already mounted which I plan to use > in the adapted version, so basically I'll just junk the existing > control board and re-use everything else. Any observations/tips? > Thanks, > P. > I would cobble together a simple, say lm317 regulator to drive your series pass driver and see what you come up with under some small loads. You may be ok with that big transformer. The power supply I built uses 4 2n3055 in parralel like what you have. Have fun.. JTT Article: 97283 of rec.radio.amateur.homebrew From: texassparky@subdimension.com Subject: 1N23W source? Date: Sat, 29 Apr 2006 12:46:52 -0500 Message-ID: Does anyone know of a source for a couple of 1N23W mixer diodes? This is not a new design, they are for repair. So, I must use the old style cartridge unit. Thanks! Mike, WB5MYY Article: 97284 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Checkin' out dummy loads with a VNA... References: <1146178584.921966.197090@y43g2000cwc.googlegroups.com> <1146188811.527595.197470@j73g2000cwa.googlegroups.com> <1146222971.004296.183710@i39g2000cwa.googlegroups.com> <1146322957.717097.248560@v46g2000cwv.googlegroups.com> Message-ID: Date: Sat, 29 Apr 2006 18:13:11 GMT Hello Paul, > It's an HP 8754A (4 to 1300Mhz) and luckily old enough to be reasonably > serviceable and repairable! > This is just as well since there is a fault with the rectangular trace, > which just appears to 'flatline' with nothing visible other than the > sweep + markers. So no nice bod plots of filters, I'm afraid. However, > the polar and phase displays seem absolutely fine. If I can just get > that one fault fixed, it'll be a great piece of test gear to have > around. I've never worked on anything this complicated before, though, > so it'll be something of a challenge! > That looks like a problem in the digital section. Just hope that none of the EPROMs suffered a memory loss. I am not sure whether they'd report a checksum error in the 8754. I had found one that had become unseated on another analyzer and the instrument produced only garbage output but reported nothing on self-test. That disappointed me a bit. The only reason I found the cause was that I opened it and looked at it long enough. Complicated they are. However, while on the troubleshooting trail in my HP4191 I sometimes came upon a large conglomeration of discretes and banged my head, asking myself "Why didn't they do that with a uA733?". And on the directional bridge they seem to have left about 10dB of dynamic range on the table for the test channel versus the ref channel. I'd have put a wee amp before the sampler. Regards, Joerg http://www.analogconsultants.com Article: 97285 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: 13.8V high current power supply Message-ID: References: <1146323696.956339.201070@j73g2000cwa.googlegroups.com> Date: Sat, 29 Apr 2006 18:51:21 GMT On 29 Apr 2006 08:14:57 -0700, paul@burridge8333.fsbusiness.co.uk wrote: >Hi all, > >You may recall me mentioning I was thinking about adapting a 24V PSU >for use at 13.8V for powering up mobile HF rigs and stuff. I had some >spare time yesterday and took this thing to bits for a better look >inside. It turns out the mains transformer has several secondary >tapping points. I discontected the DC-stab/reg side of the supply >circuitry and reconnected the secondary tapping points to lower voltage >tappings. >Now I measure 16.8V after the transformer's output has been rectified >and applied across the *big* electrolytic. This is under no-load >conditions. Now, is that 3V enough 'headroom' to use up in regulation >and stabilisation for 13.8V final output if I throw the old 28V >reg/stab away and build something from scratch? There are 6 pass >transistors plus a driver (2n3055) already mounted which I plan to use >in the adapted version, so basically I'll just junk the existing >control board and re-use everything else. Any observations/tips? >Thanks, >P. Put a load across that BIG cap and measure the voltage and ripple. I bet with a decent 20A load the ripple will be more than 3V. I suspect you do not have enough headroom to regulate it without going to a lowvoltage switchmode regulator. You want at least 16-17V at the trough of the ripple for any series pass linear regulator to work. Unloaded peak votages do not mean much. Allison Article: 97286 of rec.radio.amateur.homebrew From: ken scharf Subject: Re: Regen Question References: <1146097667.588709.301120@v46g2000cwv.googlegroups.com> <1146302393.723665.188730@j33g2000cwa.googlegroups.com> <1146315252.554822.314130@g10g2000cwb.googlegroups.com> <1146317168.517145.160430@u72g2000cwu.googlegroups.com> <7k6752hdq16jsgo6e9ncopssl504mk3d28@4ax.com> Message-ID: Date: Sat, 29 Apr 2006 18:01:58 -0400 The regeneration control either varies the amount of feedback (throttle cap, movable tickler coil, or pot across the tickler coil) OR varies the gain of the valve (or solid state device) by varying the plate voltage (pot or series resistor), screen voltage (consider the screen of the tetrode or pentode as the plate of the triode and the plate of the tetrode that of a cascaded second stage), or grid voltage (yes you can also add negative bias to the grid to lower the gain, rarely used in a regen using tubes but the ONLY way with FET's). If the variable gain method is used, then the tickler coil must have JUST the right number of turns so there is JUST the right amount of feedback for regeneration to start when the valve (or other active device) is operating at the optimal gain setting for detection. If TOO much feedback is provided the gain of the detector must be set so low that poor sensitivity results. Also adjustment of the regen will be tricky. If too little feedback is provided regeneration may not happen or the detector gain will have to be so high that the detector will be unstable. For some reason most triodes seem to operate as detectors with about 30-50 volts on the plate, and pentodes with 20-50 volts on the screen. Using a regulated supply for the detector is a good idea, especially if you want to try and receive SSB signals. The fade out problem with your regen sounds familiar, I had this problem on an old AA5 radio. It would stop playing after a while and came back if I touched the signal grid lead (antenna tuning cap hot side) of the 12BE6 tube (I actually held one end of a .01 cap and touched the OTHER side of the cap to the grid as it was a hot chassis set). Weird! Maybe I had a bad cap in the agc circuit, not sure. Allisonnospam@nouce.bellatlantic.net wrote: > On 29 Apr 2006 06:26:08 -0700, jvereker@wp.pl wrote: > > >>My mistake, it's a triode, no screen grid. :) I'm not used to American >>symbols, here in Europe we have easier sytem (EC-triode, ECC-double >>triode, etc.). For me 1H2GT and 1T4T is the same tube ;) > > >>What are the differences, advantages and disadvantages between methods >>with a pot in plate circuit, screen grid circuit, throttle cap ? > > > Apples and potatoes. Seriously screen grid valves(tubes) of the > tetrode/pentatode flavor are different animals than triodes so > applying comparison of regen throttle techniques across them > is difficult to compare. However.. with that said. > > Throttle cap is usally the best as you can optimize the tube operating > point and then only adjust the amount of feedback. Disadvantage is > there is RF on the capacitor and that means careful layout and good > mechanical mounting for stability. > > The other two vary the plate(anode) voltage and vary the screen > grid voltage are similar as they both affect the gain of the tube by > altering it's operating point. Disadvantage is that you may have > to play more with the feedback winding (or tap) so that regeration > occurs at the best point on the variable resistor or performance will > suffer. Advantage, no RF on any of the wires to the resistor so > placement and mounting is more flexible. > > Both can be made to work equally well with care. > > > Allison > > Article: 97287 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Checkin' out dummy loads with a VNA... References: <1146178584.921966.197090@y43g2000cwc.googlegroups.com> <1146188811.527595.197470@j73g2000cwa.googlegroups.com> <1146222971.004296.183710@i39g2000cwa.googlegroups.com> <1146322957.717097.248560@v46g2000cwv.googlegroups.com> <1146345471.954882.23880@v46g2000cwv.googlegroups.com> Message-ID: Date: Sat, 29 Apr 2006 23:22:46 GMT Hello Paul, > I think this item pre-dates a lot of this digital stuff; I doubt > there's a single eprom in it - and no custom chips, either! > It was built in about 1980 and doesn't go through any self-testing > routines. One has to carry out manual tests oneself. This wonderful > simplicity should hopefully enable me to keep it running indefinitely, > once I can get it fixed. Serviceability is one of my main criteria when > choosing an item of test equipment. > The HP4191A is from that era as well. However, it is one heck of a complicated machine with a computer board as large as a family-size pizza. Lots of PROMs and stuff :-( Regards, Joerg http://www.analogconsultants.com Article: 97288 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Regen Question Message-ID: References: <1146097667.588709.301120@v46g2000cwv.googlegroups.com> <1146302393.723665.188730@j33g2000cwa.googlegroups.com> <1146315252.554822.314130@g10g2000cwb.googlegroups.com> <1146317168.517145.160430@u72g2000cwu.googlegroups.com> <7k6752hdq16jsgo6e9ncopssl504mk3d28@4ax.com> Date: Sun, 30 Apr 2006 00:36:58 GMT On Sat, 29 Apr 2006 18:01:58 -0400, ken scharf wrote: >The regeneration control either varies the amount of feedback >(throttle cap, movable tickler coil, or pot across the tickler coil) >OR varies the gain of the valve (or solid state device) by varying the >plate voltage (pot or series resistor), screen voltage (consider the >screen of the tetrode or pentode as the plate of the triode and the >plate of the tetrode that of a cascaded second stage), or grid voltage >(yes you can also add negative bias to the grid to lower the gain, >rarely used in a regen using tubes but the ONLY way with FET's). I found that was not the best with fets. However, fets work best when run at best gain and the amount of feedback (regeneration) is controlled via pot or throttle cap. >If the variable gain method is used, then the tickler coil must have >JUST the right number of turns so there is JUST the right amount of >feedback for regeneration to start when the valve (or other active >device) is operating at the optimal gain setting for detection. If >TOO much feedback is provided the gain of the detector must be set >so low that poor sensitivity results. Also adjustment of the regen >will be tricky. If too little feedback is provided regeneration may >not happen or the detector gain will have to be so high that the >detector will be unstable. Mostly what I said. >For some reason most triodes seem to operate as detectors with >about 30-50 volts on the plate, and pentodes with 20-50 volts on >the screen. Using a regulated supply for the detector is a good >idea, especially if you want to try and receive SSB signals. It does help. I have a 5 tube 80m RX I built that uses a regenative detector. I didn't need the gain but for selectivity using very loose couped IF. Stability was hard to maintain without a regulated screen (6BA6 detector) source from interactions of agc and audio amp pulling the supply. Once I nailed it down it performs extemely well and is a bit narrow for AM phone with only 2 IF cans. Also for radios using tubes with directly heated filliments dropping the filiment voltage can tame the regneration a bit. >The fade out problem with your regen sounds familiar, I had this problem >on an old AA5 radio. It would stop playing after a while and came back >if I touched the signal grid lead (antenna tuning cap hot side) of the >12BE6 tube (I actually held one end of a .01 cap and touched the OTHER >side of the cap to the grid as it was a hot chassis set). Weird! The problem was likely an open antenna or oscilator coil, I've seen that before. The coil opens (broken connection) and the grid floats till its self bias drives it nuts. Inject noise and you bleed off the charge for a while. I suspect the 6M grid resistor is too high for the tube used and it's building space charge bias till it cuts off. I tried a regen using some 1AD5 (submini 1.5V filliment tube) and it didn't like grid resistors over about 4meg and it behaved the same way. the solution was lower (2.2m) grid resistor and 100PF cap. >Maybe I had a bad cap in the agc circuit, not sure. Could be. Allison > >Allisonnospam@nouce.bellatlantic.net wrote: >> On 29 Apr 2006 06:26:08 -0700, jvereker@wp.pl wrote: >> >> >>>My mistake, it's a triode, no screen grid. :) I'm not used to American >>>symbols, here in Europe we have easier sytem (EC-triode, ECC-double >>>triode, etc.). For me 1H2GT and 1T4T is the same tube ;) >> >> >>>What are the differences, advantages and disadvantages between methods >>>with a pot in plate circuit, screen grid circuit, throttle cap ? >> >> >> Apples and potatoes. Seriously screen grid valves(tubes) of the >> tetrode/pentatode flavor are different animals than triodes so >> applying comparison of regen throttle techniques across them >> is difficult to compare. However.. with that said. >> >> Throttle cap is usally the best as you can optimize the tube operating >> point and then only adjust the amount of feedback. Disadvantage is >> there is RF on the capacitor and that means careful layout and good >> mechanical mounting for stability. >> >> The other two vary the plate(anode) voltage and vary the screen >> grid voltage are similar as they both affect the gain of the tube by >> altering it's operating point. Disadvantage is that you may have >> to play more with the feedback winding (or tap) so that regeration >> occurs at the best point on the variable resistor or performance will >> suffer. Advantage, no RF on any of the wires to the resistor so >> placement and mounting is more flexible. >> >> Both can be made to work equally well with care. >> >> >> Allison >> >> Article: 97289 of rec.radio.amateur.homebrew From: ken scharf Subject: Re: Regen Question References: <1146097667.588709.301120@v46g2000cwv.googlegroups.com> <1146302393.723665.188730@j33g2000cwa.googlegroups.com> <1146315252.554822.314130@g10g2000cwb.googlegroups.com> <1146317168.517145.160430@u72g2000cwu.googlegroups.com> <7k6752hdq16jsgo6e9ncopssl504mk3d28@4ax.com> Message-ID: <8MT4g.32714$Kh5.4397@bignews8.bellsouth.net> Date: Sat, 29 Apr 2006 20:44:58 -0400 Allisonnospam@nouce.bellatlantic.net wrote: > On Sat, 29 Apr 2006 18:01:58 -0400, ken scharf > wrote: > > >>The regeneration control either varies the amount of feedback >>(throttle cap, movable tickler coil, or pot across the tickler coil) >>OR varies the gain of the valve (or solid state device) by varying the >>plate voltage (pot or series resistor), screen voltage (consider the >>screen of the tetrode or pentode as the plate of the triode and the >>plate of the tetrode that of a cascaded second stage), or grid voltage > > >>(yes you can also add negative bias to the grid to lower the gain, >>rarely used in a regen using tubes but the ONLY way with FET's). > > > I found that was not the best with fets. However, fets work best when > run at best gain and the amount of feedback (regeneration) is > controlled via pot or throttle cap. > > >>If the variable gain method is used, then the tickler coil must have >>JUST the right number of turns so there is JUST the right amount of >>feedback for regeneration to start when the valve (or other active >>device) is operating at the optimal gain setting for detection. If >>TOO much feedback is provided the gain of the detector must be set >>so low that poor sensitivity results. Also adjustment of the regen >>will be tricky. If too little feedback is provided regeneration may >>not happen or the detector gain will have to be so high that the >>detector will be unstable. > > > Mostly what I said. > > >>For some reason most triodes seem to operate as detectors with >>about 30-50 volts on the plate, and pentodes with 20-50 volts on >>the screen. Using a regulated supply for the detector is a good >>idea, especially if you want to try and receive SSB signals. > > > It does help. I have a 5 tube 80m RX I built that uses a regenative > detector. I didn't need the gain but for selectivity using very loose > couped IF. Stability was hard to maintain without a regulated > screen (6BA6 detector) source from interactions of agc and audio > amp pulling the supply. Once I nailed it down it performs extemely > well and is a bit narrow for AM phone with only 2 IF cans. > > Also for radios using tubes with directly heated filliments dropping > the filiment voltage can tame the regneration a bit. > > >>The fade out problem with your regen sounds familiar, I had this problem >>on an old AA5 radio. It would stop playing after a while and came back >>if I touched the signal grid lead (antenna tuning cap hot side) of the >>12BE6 tube (I actually held one end of a .01 cap and touched the OTHER >>side of the cap to the grid as it was a hot chassis set). Weird! > > > The problem was likely an open antenna or oscilator coil, I've seen > that before. The coil opens (broken connection) and the grid floats > till its self bias drives it nuts. Inject noise and you bleed off the > charge for a while. > > I suspect the 6M grid resistor is too high for the tube used and it's > building space charge bias till it cuts off. I tried a regen using > some 1AD5 (submini 1.5V filliment tube) and it didn't like grid > resistors over about 4meg and it behaved the same way. > the solution was lower (2.2m) grid resistor and 100PF cap. > In general using a higher grid resister and smaller capacitor results in increased selectivity and sensitivity with a loss in large signal handling ability. Visa Versa for smaller grid resister and larger coupling capacitor. Also the grid resistor can go across the capacitor or from the grid to ground. If the grid coil's cold end is NOT grounded the latter arrangement is required. In early tube manuals the recommended grid leak resistance was usually 1-2 meg ohms, with a capacitor value of 100-250pf. You have to watch the time constant there or you might end up with 'super-regeneration' where the tube breaks into a high frequency (ultra-sonic that is, around 10khz) oscillation. Article: 97290 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Regen Question Message-ID: <2u8852htdp5b4a67vn7sjq2d4i7u56qo40@4ax.com> References: <1146097667.588709.301120@v46g2000cwv.googlegroups.com> <1146302393.723665.188730@j33g2000cwa.googlegroups.com> <1146315252.554822.314130@g10g2000cwb.googlegroups.com> <1146317168.517145.160430@u72g2000cwu.googlegroups.com> <7k6752hdq16jsgo6e9ncopssl504mk3d28@4ax.com> <8MT4g.32714$Kh5.4397@bignews8.bellsouth.net> Date: Sun, 30 Apr 2006 03:06:21 GMT On Sat, 29 Apr 2006 20:44:58 -0400, ken scharf wrote: >Allisonnospam@nouce.bellatlantic.net wrote: >> On Sat, 29 Apr 2006 18:01:58 -0400, ken scharf >> wrote: >> >> >>>The regeneration control either varies the amount of feedback >>>(throttle cap, movable tickler coil, or pot across the tickler coil) >>>OR varies the gain of the valve (or solid state device) by varying the >>>plate voltage (pot or series resistor), screen voltage (consider the >>>screen of the tetrode or pentode as the plate of the triode and the >>>plate of the tetrode that of a cascaded second stage), or grid voltage >> >> >>>(yes you can also add negative bias to the grid to lower the gain, >>>rarely used in a regen using tubes but the ONLY way with FET's). >> >> >> I found that was not the best with fets. However, fets work best when >> run at best gain and the amount of feedback (regeneration) is >> controlled via pot or throttle cap. >> >> >>>If the variable gain method is used, then the tickler coil must have >>>JUST the right number of turns so there is JUST the right amount of >>>feedback for regeneration to start when the valve (or other active >>>device) is operating at the optimal gain setting for detection. If >>>TOO much feedback is provided the gain of the detector must be set >>>so low that poor sensitivity results. Also adjustment of the regen >>>will be tricky. If too little feedback is provided regeneration may >>>not happen or the detector gain will have to be so high that the >>>detector will be unstable. >> >> >> Mostly what I said. >> >> >>>For some reason most triodes seem to operate as detectors with >>>about 30-50 volts on the plate, and pentodes with 20-50 volts on >>>the screen. Using a regulated supply for the detector is a good >>>idea, especially if you want to try and receive SSB signals. >> >> >> It does help. I have a 5 tube 80m RX I built that uses a regenative >> detector. I didn't need the gain but for selectivity using very loose >> couped IF. Stability was hard to maintain without a regulated >> screen (6BA6 detector) source from interactions of agc and audio >> amp pulling the supply. Once I nailed it down it performs extemely >> well and is a bit narrow for AM phone with only 2 IF cans. >> >> Also for radios using tubes with directly heated filliments dropping >> the filiment voltage can tame the regneration a bit. >> >> >>>The fade out problem with your regen sounds familiar, I had this problem >>>on an old AA5 radio. It would stop playing after a while and came back >>>if I touched the signal grid lead (antenna tuning cap hot side) of the >>>12BE6 tube (I actually held one end of a .01 cap and touched the OTHER >>>side of the cap to the grid as it was a hot chassis set). Weird! >> >> >> The problem was likely an open antenna or oscilator coil, I've seen >> that before. The coil opens (broken connection) and the grid floats >> till its self bias drives it nuts. Inject noise and you bleed off the >> charge for a while. >> >> I suspect the 6M grid resistor is too high for the tube used and it's >> building space charge bias till it cuts off. I tried a regen using >> some 1AD5 (submini 1.5V filliment tube) and it didn't like grid >> resistors over about 4meg and it behaved the same way. >> the solution was lower (2.2m) grid resistor and 100PF cap. >> >In general using a higher grid resister and smaller capacitor results >in increased selectivity and sensitivity with a loss in large signal >handling ability. Visa Versa for smaller grid resister and larger >coupling capacitor. Also the grid resistor can go across the capacitor >or from the grid to ground. If the grid coil's cold end is NOT grounded >the latter arrangement is required. In early tube manuals the >recommended grid leak resistance was usually 1-2 meg ohms, with a >capacitor value of 100-250pf. You have to watch the time constant >there or you might end up with 'super-regeneration' where the tube >breaks into a high frequency (ultra-sonic that is, around 10khz) >oscillation. All thats true. I've built more than a few tube, transistor and fet regens in the last 40 years. However many tubes the maximum resistance from grid to ground is limited or it developes a "contact" bias and performance is not as predicted. However the important item is there is a path from grid to ground and it's total resistance is not too high (1AD5 4meg was borderline too high). Other tubes I've used (12BA6) that resistance could be 10meg it behaves well where with a 12EK6(12v space charge tube) was happiest with 5meg. It's always tougher with directly heated tubes like (3S4, 3A6, 1AD5) as the filliment has a voltage gradient across it making one end of the "cathode" at ground and the other end equal to filliment battery potential. That makes for interesting effects and also makes a difference which end of filliment battery is grounded relative to the plate (anode) supply. Also super regeneration is not a bad thing, many of the upper hf and VHF regens employ it to get even better perfomance than a straight regen. The most interesting regen I've made used a 6DS4 nuvistor (high Mu triode) with 20-50 volts for plate. Those little ceramic metal tubes are less microphonic and really do perfom well. All of the little details that make a regens interesting to work with. FYI: QST November 2003 had a really nice two tube superhet/regen using 12V space charge tubes (12ad6, 12ek6) thats fun to play with. The 12AD6 is similar to 6be6 but only needs 12V on the plate and the 12ek6 is similar to the 12ba6 with the same 12V plate voltage operating capability. Allison Article: 97291 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: 13.8V high current power supply Message-ID: References: <1146323696.956339.201070@j73g2000cwa.googlegroups.com> <1146357642.620733.175050@y43g2000cwc.googlegroups.com> Date: Sun, 30 Apr 2006 03:11:18 GMT On 29 Apr 2006 17:40:42 -0700, paul@burridge8333.fsbusiness.co.uk wrote: >You're probably right! I did actually try to rip the heating element >out of a 2kW electric fire to use as just such a test load, but the >manufacturers had used some really devious sort of screw heads to keep >the two casings together. :-( My favorite high current 12V load is auto headlamps average sealed beam is not less than 80W often as much as 120W so two are easily a 10-20A load. Some of the halogen lamps are higher power but get very hot (caution). the key thing is enough load to simulate a radio and parallel lamps of sufficient power will do that safely. >Failing some serious resistance wire, the only other 'to hand' option >is to hook up the HF mobile and key-up; but I don't have a sufficiently >gutsy dummy load or antenna to dump 100W into, I'm afraid. :-( that is a bad idea if the voltage gets too high bad things could happen. Allison Article: 97292 of rec.radio.amateur.homebrew From: "west" Subject: Coax & Rotor Bulkhead Message-ID: Date: Sun, 30 Apr 2006 03:47:32 GMT Is there a place on the net, in a book, etc. that I can see examples & diagrams of a coax bulkhead? Perhaps someone on this NG constructed such a device & wouldn't mind sharing his plans. My house sits on a slab and I would like to run about 4 or 5 coax cables, rotor cable, AC & DC source all going from the shack to my tower. In Florida lightning is a major concern so the bulkhead will have to have coax (gas arrestors?) & other types of arrestors. All this, of course, should be grounded to a copper ground rod. I would like this outside "box" nicely & neatly dressed & labeled so it's easy to disconnect & is not an eye sore. I searched the Ham books and many Internet sights to no avail. Anybody? Thank you. west, AF4GC Article: 97293 of rec.radio.amateur.homebrew From: Win Subject: Re: Roller Inductor Squeak Date: Sun, 30 Apr 2006 13:07:45 -0500 Message-ID: References: <1146306349.377976.31410@u72g2000cwu.googlegroups.com> On 29 Apr 2006 03:25:49 -0700, "Leon" wrote: > >Win wrote: >> What is a good conductive lub to use on roller indictors? The >> inductor in my tunert squeaks like an old door. Any other tips to >> keep that roller noise down? >> >> Win, w0lz > >Electrolube used to make a contact lubricant pen. Perhaps they are >still available. > >Leon Thanks, Leon. I will do a search for it to the WEB. Win, w0lz Article: 97294 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Regen Question Message-ID: References: <1146302393.723665.188730@j33g2000cwa.googlegroups.com> <1146315252.554822.314130@g10g2000cwb.googlegroups.com> <1146317168.517145.160430@u72g2000cwu.googlegroups.com> <7k6752hdq16jsgo6e9ncopssl504mk3d28@4ax.com> <8MT4g.32714$Kh5.4397@bignews8.bellsouth.net> <2u8852htdp5b4a67vn7sjq2d4i7u56qo40@4ax.com> <1146424500.578971.92870@j73g2000cwa.googlegroups.com> Date: Sun, 30 Apr 2006 19:30:40 GMT On 30 Apr 2006 12:15:00 -0700, dconley@lawfacts.com wrote: >"Other tubes I've used (12BA6) that resistance could be 10meg it >behaves >well where with a 12EK6(12v space charge tube) was happiest >with 5meg." > >I'm thinking of putting a 10 ohm pot in series with the filament of the >regen tube to see if making the filament less negative in relation to >the regen grid might work, maybe also using a bypass cap across the >pot. I don't have one right now but I'm going to play around with >different resistor values (like around 3 ohms) until I can order one. > >Did you think about doing something like this when you couldn't get >your 12EK6's to work with a 10 meg resistor? 12EK6 is a 12V indirectly heated cathode and is of the space charge design (special construction for 12v anode power) so the control grid does not like high resistances or it developes an excessive contact charge from the electron flow within. Being a pentatode it already has a lot of gain compared to a triode so pressing it that way is not required. Also direct vs indirect heated cathode are different. Allison Article: 97295 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Checkin' out dummy loads with a VNA... References: <1146178584.921966.197090@y43g2000cwc.googlegroups.com> <1146188811.527595.197470@j73g2000cwa.googlegroups.com> <1146222971.004296.183710@i39g2000cwa.googlegroups.com> <1146322957.717097.248560@v46g2000cwv.googlegroups.com> <1146345471.954882.23880@v46g2000cwv.googlegroups.com> <1146403202.636228.14750@v46g2000cwv.googlegroups.com> Message-ID: Date: Sun, 30 Apr 2006 21:22:32 GMT Hello Paul, > Well I'm sorry to hear that. As an analogue guy, I don't much care for > PROMS and stuff. I can fix up anything analogue in good time, given a > schematic and a decent range of test equipment, but am off my territory > with digital stuff. But I'm still not sure what the problem is here. > Are you saying spares for the digital parts are hard to obtain or > rather that the encoding on those chips may be hard to reprogram? > Not sure yet what is broken. The analog sampling stuff and all seems to work but is reads out garbage. The PROMs are really old style. They look posh with gold plating and all but I guess that non-programmed spares would be next to impossible to find. But again, maybe they are still ok. Hopefully... Regards, Joerg http://www.analogconsultants.com Article: 97296 of rec.radio.amateur.homebrew From: Win Subject: Re: Roller Inductor Squeak Date: Sun, 30 Apr 2006 18:41:23 -0500 Message-ID: <6nia525alfh0raf75fuu2h1a9rm8n4ecrs@4ax.com> References: <1146306349.377976.31410@u72g2000cwu.googlegroups.com> <1146438836.353852.10720@j33g2000cwa.googlegroups.com> On 30 Apr 2006 16:13:56 -0700, "K7ITM" wrote: >I'd try Caig De-oxit #5, I think it is. It's not specifically >conductive, but it's used on noisy contacts and controls, and acts as a >cleaner and lubricant. Other similar cleaner-lubricants should work, >too, but Caig has a very good reputation. > >Cheers, >Tom Thanks,Tom. I receiveed the same suggestion via email. I will look into it. Win, w0lz Article: 97297 of rec.radio.amateur.homebrew From: Bill Powell Subject: Simple Tone Detector? Message-ID: Date: Mon, 01 May 2006 01:34:52 GMT Simple Tone Detector I'm looking for a SIMPLE circuit to detect the presence of a tone - any tone in the audible range. My quest: Consider the poor radio dispatcher, sitting there wearing a pair of headphones when the next town / county over tones out an ambulance or fire department. I'm looking to be able to detect any audible tone and use the results to decrease the operator's headphone sound level during the tone. I have already tried a DSP tone elimination and found that: 1) It's too effective: I need do decrease tone volume - not eliminate it. 2) Way too complex and expensive for the seemingly simple task. The circuit needs to be compact and inexpensive - connected between the dispatch console headphone jack and the operator's headphones. It must NOT interfere with normal speech! I have spent several hours online seatching and came up empty. Any thoughts or suggestions? Bill Powell Article: 97298 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Thermistors! Ah!! Message-ID: References: <1146273161.372023.247350@j73g2000cwa.googlegroups.com> <1146436436.324149.14790@y43g2000cwc.googlegroups.com> Date: Mon, 01 May 2006 01:38:02 GMT On 30 Apr 2006 15:33:56 -0700, "Telstar Electronics" wrote: >Thermistors can certainly go bad. Pull it out and test it with an Ohm >meter while heating and cooling. > >www.telstar-electronics.com Thermisters in low power circuits (sensing) are very reliable. This only time I've seen them fail is when they are expected to handle power directly and I'd bet this is not the case for the radio. However, they can sometimes drift up in value and the circuit they are hooked to and do funky thing as well. Simply changing the thermister is not always direct answer unless you have the correct part (yes they come in different values). the circuit may have a fault as well and if there is a threshold adjustment (pot) that can be altered if things get too hot for you liking. Often the circuit is a comparator so there are other components that can fail as well. Allison