[AMRadio] Home Brew AM Transmitter Wanted
Anyone out there have a well constructed home brew AM transmitter that is laying around collecting dust? I am looking for one that runs 350-1000W out and can be fully integrated or one that uses a driver for the RF and modulator. If you have one that you would be willing to part with, give me a call at 813-643-3034 or E Mail me. Thanks for reading Bob Maser W6TR in Florida
Re: [AMRadio] Home Brew AM Transmitter Wanted
Bob Maser wrote: Anyone out there have a well constructed home brew AM transmitter that is laying around collecting dust? I am looking for one that runs 350-1000W out and can be fully integrated or one that uses a driver for the RF and modulator. If you have one that you would be willing to part with, give me a call at 813-643-3034 or E Mail me. Thanks for reading Hey, Bob.. why not just build one? I'm sure that somewhere here on the list, you could probably find all the parts and tubes you need to build your own. I'm sure that there are some people here that would nearly give you the parts, just to encourage another home-brewing ham. You could probably run a single 450TH/L, 304TH/L ... how about an 813 in the final, modulated by a pair of 811's? The only problem you might have is finding the iron/transformers. But, it never hurts to ask ;-) -- 73 = Best Regards, -Geoff/W5OMR A: Yes. Q: Are you sure? A: Because it reverses the logical flow of conversation. Q: Why is 'top posting' annoying in email?
RE: [AMRadio] Home Brew AM Transmitter Wanted
Building is a LOT of work, but fun. If you was to ask me, there is not a lot out there for a reasonable price that is not homebrew and is worth a crap. 30K1, KW1, T368 BC610, Johnson kilowatt, old broadcast TX. It's a shame I am so attached to my homebrew stuff or I would sell it and build more. A pair of 813's at 2000 or so volts does real well, about 600 watts out. A pair of 812a's or 811a's does about 300 watts easy, and with 811a modulators is a simple stable rig. The 4-125/250/400 need 3000 volts or more to be real happy, and that is a stress on some parts. The hard parts to get seem to be high voltage variable capacitors, high power switches, old plug in coils that have not turned to dust, high voltage oil filled caps, and big iron. On my last transmitter, I wound a pie net coil using copper tubing. Finding lots of nice looking matching meters is hard. I must have huge amounts of money and time in my homebrew rigs, and I cant imagine selling them for any reasonable price and being happy about it. I sold my 30K-1 and did not worry about it. On the other hand, I have seen homebrew stuff at ham fests that they would have to pay me to take... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W5OMR/Geoff Sent: Tuesday, March 28, 2006 11:44 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew AM Transmitter Wanted Bob Maser wrote: Anyone out there have a well constructed home brew AM transmitter that is laying around collecting dust? I am looking for one that runs 350-1000W out and can be fully integrated or one that uses a driver for the RF and modulator. If you have one that you would be willing to part with, give me a call at 813-643-3034 or E Mail me. Thanks for reading
[AMRadio] Home Brew 4-1000 amp
From: Byron Lichtenwalner [EMAIL PROTECTED] To: amradio@mailman.qth.net Subject: Home Brew 4-1000 amp Date: Thursday, May 26, 2005 12:20 AM Friends Yesterday I bought a great looking amp (see http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=5775631689ssPageName=ADME:B:EOAB:US:6 ) , only to find I had misunderstood the shipping costs. It is now mine, but stranded in Arizona. If anyone is interested, make me an offer. The best offer will get it, but you get to pay the shipping, or better pick it up. It's a 400 pound (approximate) monster. Private responses please to [EMAIL PROTECTED] Best offer by Friday at 8 A.M. gets it. Byron, W3WKR
Re: [AMRadio] Home Brew
I know this is an older post, but in the event anyone wants to do this, I have the article from 10th edition(1946) West Coast handbook with this circuit in it. Joe W4AAB - Original Message - From: John Coleman [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Tuesday, September 28, 2004 6:08 PM Subject: RE: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, September 28, 2004 2:50 PM To: amradio@mailman.qth.net Subject: [AMRadio] Home Brew Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home brew AM
Patrick, That Altec amplifier sure is nice! I really like the 5R4 full wave bridge rectifier with the extra filament taps off the HV windings. Never seen that done before. Also the 6W6 triode connected cathode follower stage is unique with the center tapped choke. I see negative feedback from the output tranny all the way back to the first preamp stage. Without getting too far into audio jargon, how do two of these beasts sound as a stereo amplifier? The HV filter only has 6 uf as part of a LC filter, so how is the bass response? Got a few dozen of these lying around? :) Regards, Jim Candela WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Patrick Jankowiak Sent: Monday, October 04, 2004 7:32 PM To: amradio@mailman.qth.net; [EMAIL PROTECTED] Subject: Re: [AMRadio] Home brew AM I would say that the fidelity was pretty good compared to a BC-610, mostly because the audio amplifier was of exceptional quality and so lightly loaded. The power at carrier was pretty low, only about 80 watts, and when we were done tweeking, we were getting about a 340 watt PEP signal out of it. Running the power low, with low voltage and current allowed the rare tube to stay cool. As for power, I imagine the BC-610's carrier is much more powerful. The modulator amplifier is rated at 175 watts and is an Altec 1570B, using two 811A's in class B push pull with the grids driven directly from cathodes of some beam power tubes, the schematic of this unit is here: http://www.soundpractices.com/altec.html It has 10 tubes, and operates with 930VDC on the 811A's. I use two of these amps in my stereo. best regards, Patrick From: Brian Carling [EMAIL PROTECTED] Subject: Re: [AMRadio] Home brew AM How does that compare to the performance of say the 250TH final stage in a BC-610? It sounds like you are running at lower power. Also how many tubes do you use in the cathode modulator? On 2 Oct 2004 at 20:12, Patrick Jankowiak wrote: Cathode mod works very well on a 250TH. We are getting 80-90 watts carrier no problem at 2200V. For the details: http://www.montagar.com/~patj/cathmod01.htm Patrick __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.772 / Virus Database: 519 - Release Date: 10/1/2004 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.772 / Virus Database: 519 - Release Date: 10/1/2004
Re: [AMRadio] Home brew AM Cathode modualtion
I appreciate all of the suggestions. I'm not locked into a particular tube configuration yet, but I have to admit there is something appealing about running the 450TH. It's probably my mental image of two of them lit up behind a glass window in the front panel :) Clay W7CE - Original Message - From: John Coleman, ARS WA5BXO [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Sunday, October 03, 2004 12:37 PM Subject: RE: [AMRadio] Home brew AM Cathode modualtion The Rice neutralization circuit works better with a higher Q grid tank and, if possible, some input swamping or grid load resistor. The biggest trouble with the circuit is that the loading of the grid tank is not constant over the full RF cycle as a result the Q and balance is shifted somewhat over the period of the RF cycle. Starting with a higher Q or C value is one way of minimizing this effect. The circuit does work because I used it as well and also with a 304TLs, back in the days of experimenting with the ultra modulation or balanced high level modulation circuits. I eventually went to standard Push Pull. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donald Chester Sent: Sunday, October 03, 2004 12:45 PM To: amradio@mailman.qth.net Subject: RE: [AMRadio] Home brew AM Cathode modualtion The 450th is a big triode, so I don't think you can run it single ended pie net output, you would need to do 2 250th tubes in push pull or something, but the 450th would do the cathode modulator quite well. You could use a single-ended pi-network type output circuit, with a balanced grid tank coil. That is knows as Rice neutralisation. You don't get as perfect null as you can with a balanced plate tank cincuit or a pushpull arrangement, but it works well enough that it became the standard design of tube type broadcast transmitters starting in the late 50's. I used that circuit with the first high power rf final I ever built, using a 304-TL in the final, because I didn't have a large split stator tuning capacitor on hand. Don K4KYV __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home brew AM
How does that compare to the performance of say the 250TH final stage in a BC-610? It sounds like you are running at lower power. Also how many tubes do you use in the cathode modulator? On 2 Oct 2004 at 20:12, Patrick Jankowiak wrote: Cathode mod works very well on a 250TH. We are getting 80-90 watts carrier no problem at 2200V. For the details: http://www.montagar.com/~patj/cathmod01.htm Patrick __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home brew AM Cathode modualtion
The 450th is a big triode, so I dont think you can run it single ended pie net output, you would need to do 2 250th tubes in push pull or something, but the 450th would do the cathode modulator quite well. You could use a single-ended pi-network type output circuit, with a balanced grid tank coil. That is knows as Rice neutralisation. You don't get as perfect null as you can with a balanced plate tank cincuit or a pushpull arrangement, but it works well enough that it became the standard design of tube type broadcast transmitters starting in the late 50's. I used that circuit with the first high power rf final I ever built, using a 304-TL in the final, because I didn't have a large split stator tuning capacitor on hand. Don K4KYV
RE: [AMRadio] Home brew AM Cathode modualtion
The Rice neutralization circuit works better with a higher Q grid tank and, if possible, some input swamping or grid load resistor. The biggest trouble with the circuit is that the loading of the grid tank is not constant over the full RF cycle as a result the Q and balance is shifted somewhat over the period of the RF cycle. Starting with a higher Q or C value is one way of minimizing this effect. The circuit does work because I used it as well and also with a 304TLs, back in the days of experimenting with the ultra modulation or balanced high level modulation circuits. I eventually went to standard Push Pull. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donald Chester Sent: Sunday, October 03, 2004 12:45 PM To: amradio@mailman.qth.net Subject: RE: [AMRadio] Home brew AM Cathode modualtion The 450th is a big triode, so I don't think you can run it single ended pie net output, you would need to do 2 250th tubes in push pull or something, but the 450th would do the cathode modulator quite well. You could use a single-ended pi-network type output circuit, with a balanced grid tank coil. That is knows as Rice neutralisation. You don't get as perfect null as you can with a balanced plate tank cincuit or a pushpull arrangement, but it works well enough that it became the standard design of tube type broadcast transmitters starting in the late 50's. I used that circuit with the first high power rf final I ever built, using a 304-TL in the final, because I didn't have a large split stator tuning capacitor on hand. Don K4KYV __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home brew AM
Thanks for the info Jim. I will add this to the Boatanchors Directory... There are several other AM Cathode Mod links there too http://www.af4k.com/Boatanchors_Directory/ On 1 Oct 2004 at 21:43, Jim candela wrote: Guys, I have accumulated a couple of circuits for series cathode modulation. One is for a 6146 final, and the other for a 807 final, and both use a sweep tube or two for the cathode modulator. Using this technique for QRO AM at 375 watts carrier output will be pretty inefficient since the modulator tube will likely be class A. It could be class D or E switch mode with a good Low pass filter. I believe that some early KA1SI PDM rigs used some big tubes this way. As for the filament transformer, a high standoff is really no big deal so long as you wind it yourself and insulate accordingly. Heck I once made a 208 VAC to 60 VCT at 200 amps where I needed 120 KV insulation primary to secondary. Layers of Mylar sheet (like shingles) and transformer oil did the trick. Could also maybe use a ferrite horizontal fly back transformer (custom wound) for the filament. Why use 60 hertz? Could be 50 Khz so long as the filament is at the right temperature. Here is a link to two different cathode modulated AM rigs: http://pages.prodigy.net/jcandela/Modulator/ Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Brett gazdzinski Sent: Friday, October 01, 2004 7:42 AM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home brew AM Clay, Sounds like a cool idea, and I always thought it should work well since there is no mod iron. I would go for a lower output using lower voltage though, with different tubes. 4500 volts is a lot to expect a filament transformer to handle, and if it arcs over, it could be into the 110 ac side! The 450th is a big triode, so I dont think you can run it single ended pie net output, you would need to do 2 250th tubes in push pull or something, but the 450th would do the cathode modulator quite well. It would be interesting to look at what available tubes would work with this type of circuit. There are some nice modern tubes to play with, 3cx800's and other big triodes, or, if it could work, tetrodes. Not sure how cathode modulating a tetrode would work out. If you could cathode modulate a pie net output tetrode, that would open up a lot of possibilities. Maybe find one that runs a lower voltage but is good for some power... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Clay W7CE Sent: Thursday, September 30, 2004 12:52 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home brew AM One option that isn't discussed often because it is considered inefficient at high power is series cathode modulation. This is accomplished by putting the modulator tube between the RF amplifier tube's cathode and ground. The only apparent inefficiency is that you run the RF amp at one fourth of it's Class C CW power rating. I'm currently considering building such a rig using a 450TH for the RF amp and another 450TH for the modulator. At 4500V, the 450TH is good for about 1500W out on CW, and with the modulator tube added will drop to about 375W of carrier. On modulation peaks it will hit the tubes CW power level of 1500W. The tube will be doing fairly light duty at this power level since it can handle 1500W CCS output at 4500V, and should last a very long time as a result. Based on the price and weight of 450TH's vs. large mod transformers, I think it's a good trade off. In addition, the fidelity and audio response will be limited primarily by the audio driver, not the mod transformer. On the negative side, I have to run the plates at 4500V vs. about 2500V for plate modulation. The filament transformer for the RF amp will also need to be hi-pot tested to 4500-5000V (anyone willing to part with a pair of 7.5V, 12A filament transformers that will work for this?). Any thoughts and advice on this approach will be appreciated. Clay W7CE - Original Message - From: Brett gazdzinski [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Thursday, September 30, 2004 9:03 AM Subject: RE: [AMRadio] Home brew AM That would be hard, but not impossible. You would need to read up on mod transformer construction, find something to use as a core, and wind loads of wire on it, keeping in mind the very high voltages that it would have to withstand. You can buy mod transformers, peter dahl makes new ones, ebay, etc. Old surplus is best, old military rigs, broadcast rigs, old ham rigs... I am using mod transformers that were built by RCA in the 1940's for some sort of ship board radio for the Dutch navy I have been told. Without any mod iron, you would have to go to some sort of screen modulation with large tubes. Brett N2DTS -Original
RE: [AMRadio] Home brew AM Cathode modualtion
My two cent worth for the new guys that might not understand: The technique that is used in the drawing of Jim's (JKO) showed a 6146 in the final. This circuit is simply a class A audio circuit that has been placed in series with the finals B+ and screen common circuit. In this case the grid leak bias resistor has been returned to the cathode so that the grid bias on the final stays constant with modulation (except for the small usual grid leak self modulation phenomenon that occurs on any high level modulated stage with grid leak bias) The circuit could be modified placing the modulators in series with the +1100 volt DC input and the results would be the same (see note 1). The plate efficiency of the Class C final is as good as any, but the modulators will dissipate a lot of heat because of the class A operation with less that 25% efficiency. The overall efficiency is not good. The beauty of this circuit is no modulation XFMR with a trade off for modulator efficiency. It does require a separate filament source with good insulation for the class C final to prevent filament to cathode breakdown and make sure you get all the RF bypassed or filtered on the final's cathode. It also requires twice as much DC supply voltage. (NOTE 1) Placing the modulator tubes in the cathode return of the final, as shown, is a better construction technique that allows the modulator cathodes to be grounded or biased in a normal manor (close to ground potential, therefore allowing for normal RC coupling to the grids of the modulator tubes). If the circuit were modified, placing the modulator tube in the plate circuit, then the cathode of the modulators would be at a very high voltage. This would mean that the coupling to the grid of the modulator would need special consideration or XFMR coupling, defeating the one of the purposes of the circuit. Also, the filament source for the modulators would need to be connected to the cathode of the modulators and a special filament supply winding with good insulation would be needed to handle the high voltage that would be on the modulators. None the less, theory of operation to the final is the same. It is still high level modulation. The secondary of a modulation XFMR could be place where the series modulator tubes are, and the supply voltage dropped by the amount used by the series modulator tubes, and there would be no difference than if the modulation transformer were placed where you commonly see it in the plate circuit of the final. Good Luck, John, WA5BXO
Re: [AMRadio] Home brew AM
Cathode mod works very well on a 250TH. We are getting 80-90 watts carrier no problem at 2200V. For the details: http://www.montagar.com/~patj/cathmod01.htm Patrick
RE: [AMRadio] Home brew AM
Clay, Sounds like a cool idea, and I always thought it should work well since there is no mod iron. I would go for a lower output using lower voltage though, with different tubes. 4500 volts is a lot to expect a filament transformer to handle, and if it arcs over, it could be into the 110 ac side! The 450th is a big triode, so I dont think you can run it single ended pie net output, you would need to do 2 250th tubes in push pull or something, but the 450th would do the cathode modulator quite well. It would be interesting to look at what available tubes would work with this type of circuit. There are some nice modern tubes to play with, 3cx800's and other big triodes, or, if it could work, tetrodes. Not sure how cathode modulating a tetrode would work out. If you could cathode modulate a pie net output tetrode, that would open up a lot of possibilities. Maybe find one that runs a lower voltage but is good for some power... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Clay W7CE Sent: Thursday, September 30, 2004 12:52 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home brew AM One option that isn't discussed often because it is considered inefficient at high power is series cathode modulation. This is accomplished by putting the modulator tube between the RF amplifier tube's cathode and ground. The only apparent inefficiency is that you run the RF amp at one fourth of it's Class C CW power rating. I'm currently considering building such a rig using a 450TH for the RF amp and another 450TH for the modulator. At 4500V, the 450TH is good for about 1500W out on CW, and with the modulator tube added will drop to about 375W of carrier. On modulation peaks it will hit the tubes CW power level of 1500W. The tube will be doing fairly light duty at this power level since it can handle 1500W CCS output at 4500V, and should last a very long time as a result. Based on the price and weight of 450TH's vs. large mod transformers, I think it's a good trade off. In addition, the fidelity and audio response will be limited primarily by the audio driver, not the mod transformer. On the negative side, I have to run the plates at 4500V vs. about 2500V for plate modulation. The filament transformer for the RF amp will also need to be hi-pot tested to 4500-5000V (anyone willing to part with a pair of 7.5V, 12A filament transformers that will work for this?). Any thoughts and advice on this approach will be appreciated. Clay W7CE - Original Message - From: Brett gazdzinski [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Thursday, September 30, 2004 9:03 AM Subject: RE: [AMRadio] Home brew AM That would be hard, but not impossible. You would need to read up on mod transformer construction, find something to use as a core, and wind loads of wire on it, keeping in mind the very high voltages that it would have to withstand. You can buy mod transformers, peter dahl makes new ones, ebay, etc. Old surplus is best, old military rigs, broadcast rigs, old ham rigs... I am using mod transformers that were built by RCA in the 1940's for some sort of ship board radio for the Dutch navy I have been told. Without any mod iron, you would have to go to some sort of screen modulation with large tubes. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of GGLL Sent: Wednesday, September 29, 2004 7:55 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home brew AM Hello people, I agree with the nice look and smell of glass AM. Few years ago, I made my CW/AM transmitter, with an 807 plate/screen modulated, 50 watts CW, 40 watts AM output. Started with a triode/pentode oscillator/doubler VFO, then converted to solid state oscillator/buffer, followed by a tube driver (6BQ5) and finally the 807 to a pi tank output. Making my own plate modulated transmitter (200..300 watts out) is a buzzing idea in my mind since a couple of months. But here the most difficult item to get is the modulation transformer, does someone know a method to build it by myself?. Many thanks in advance Best regards Guillermo - LU8EYW. Brett gazdzinski escribió: Steve, What do you need, everything? Here's a partial list of what you need: 3 Chassis 17x3x14, 3 panels 19x10.25?, 3 sets of side supports, Power transformer to give 1500 volts at 500 plus ma, Choke at 500 plus ma, two is better, swinging for the modulator, Rectifiers (I like the k2aw? bricks), Modulation transformer, Bleeder resistors, Big relay and time delay relay for step start if you go that route, 4 Tube sockets, Filament transformers, Killowatt plug in tank coils and its socket and swinging link, Push pull grid coils for the bands wanted, Push pull grid tuning cap (150 to 200 pf per section, low voltage) Modulator grid drive transformer 8 to 10,000 ohms roughly at 20 or more watts, 2 Neutralizing caps, 4
Re: [AMRadio] Home Brew
Hi Brett, Would your friend with the full garage be interested in selling a mod transformer? I've been slowly gathering parts for an 2-813 by 2-813 transmitter and would be interested if he is. Thanks, Larry Brett gazdzinski wrote: A very good choice! Build it right, and it works like a Swiss watch, and is quiet, no fans or blowers needed. 250 to 300 watts out easy, with plenty of audio to go with the carrier. The tubes are easy to find and cheap, there were many surplus transformers that would power the setup nicely, mod transformer size is reasonable. Fair radio used to sell a Collins solder sealed power transformer that would give about 1000 volts at 600 ma full wave center tapped choke input, small size, 110 or 220 volt primary, used to go for $30.00! Variac it and it does 0 to 1500 volts, and will do the rf and mod decks if you want to keep things really simple. I have tried 812a's, 811a's, 572b's in the rf deck, and they all work fine and act the same as far as modulation, drive, and power output go. I have 3 old RCA mod transformers that work with this combo very well, and also work well with the pair of 813's and 4x150a's. 10,500 to 4350 ohms I think they are, and large! They are around, a friend has a garage full of them. I retired the cvm5, as the freq response was quite poor. Building a homebrew rig is incredibly fun, and quite a source of pride if you take the time to build it RIGHT so it works trouble free for years and years, and looks nice. To get parts, you have to network hams, look on ebay, go to fests, buy old homebrew pieces of crap for the parts, and use some of the vendors that sell rf stuff. Even building receivers has not been a problem for me, parts are around, you just have to dig for them instead of going to one place like in the old days. Often, the prices are very reasonable, I picked up a bunch of nice oil filled caps for $10.00 each at Gaithersburg fest last year. I got about 6 of them. They still make new ones, but they wanted $120.00 each! The two big fun points are the chassis chess part, where you Figure out just where things are going, and how you are going to keep things symmetrical, rf and front panel, and the initial testing. Building something, and firing it up and finding it works great is quite fun, and the fun continues every time you use the rig. It also gives plenty to talk about, there is not a lot to say about a rice box into an amp. Old vintage ham gear like Johnson 500, Collins 30k-1, globe king 400/500, and military surplus like the T368, art13, and others can be fun to play with, and sometimes turn up at reasonable prices (but not on ebay). 80 meter night time is hard to break into, and needs good power levels, but 40 in the daytime is very friendly and you can do nicely with 100 watts and up. Valliant's, the Collins 32v series, dx100's, and others in that power class do very well on 40 meters, are fun to play with, and can be got at reasonable prices. People think they are expensive because they used to get them at fests for $10 or $20, but if you pay $500.00 for a 32v3, I think you got a lot of rig (and fun) for the money. The same money gets you an old crappy plastic rice box. Pay $3000.00 for a 30k-1 or some other bigger rig, and you have a lot of fun for the money, people spend that on little plastic boxes that put out 25 or 50 watts! For a lot of guys, playing with the equipment is as much fun as yakking into it. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Coleman Sent: Tuesday, September 28, 2004 7:08 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home Brew
Ooops, sorry, didnt mean to send this to the list, but since I did, havnt heard from Brett yet of course but I'm in the market for a good mod xformer for a 4x 813 transmitter if anyone has one available they'ed like to sell. thanks, Larry Larry Roohr wrote: Hi Brett, Would your friend with the full garage be interested in selling a mod transformer? I've been slowly gathering parts for an 2-813 by 2-813 transmitter and would be interested if he is. Thanks, Larry Brett gazdzinski wrote: A very good choice! Build it right, and it works like a Swiss watch, and is quiet, no fans or blowers needed. 250 to 300 watts out easy, with plenty of audio to go with the carrier. The tubes are easy to find and cheap, there were many surplus transformers that would power the setup nicely, mod transformer size is reasonable. Fair radio used to sell a Collins solder sealed power transformer that would give about 1000 volts at 600 ma full wave center tapped choke input, small size, 110 or 220 volt primary, used to go for $30.00! Variac it and it does 0 to 1500 volts, and will do the rf and mod decks if you want to keep things really simple. I have tried 812a's, 811a's, 572b's in the rf deck, and they all work fine and act the same as far as modulation, drive, and power output go. I have 3 old RCA mod transformers that work with this combo very well, and also work well with the pair of 813's and 4x150a's. 10,500 to 4350 ohms I think they are, and large! They are around, a friend has a garage full of them. I retired the cvm5, as the freq response was quite poor. Building a homebrew rig is incredibly fun, and quite a source of pride if you take the time to build it RIGHT so it works trouble free for years and years, and looks nice. To get parts, you have to network hams, look on ebay, go to fests, buy old homebrew pieces of crap for the parts, and use some of the vendors that sell rf stuff. Even building receivers has not been a problem for me, parts are around, you just have to dig for them instead of going to one place like in the old days. Often, the prices are very reasonable, I picked up a bunch of nice oil filled caps for $10.00 each at Gaithersburg fest last year. I got about 6 of them. They still make new ones, but they wanted $120.00 each! The two big fun points are the chassis chess part, where you Figure out just where things are going, and how you are going to keep things symmetrical, rf and front panel, and the initial testing. Building something, and firing it up and finding it works great is quite fun, and the fun continues every time you use the rig. It also gives plenty to talk about, there is not a lot to say about a rice box into an amp. Old vintage ham gear like Johnson 500, Collins 30k-1, globe king 400/500, and military surplus like the T368, art13, and others can be fun to play with, and sometimes turn up at reasonable prices (but not on ebay). 80 meter night time is hard to break into, and needs good power levels, but 40 in the daytime is very friendly and you can do nicely with 100 watts and up. Valliant's, the Collins 32v series, dx100's, and others in that power class do very well on 40 meters, are fun to play with, and can be got at reasonable prices. People think they are expensive because they used to get them at fests for $10 or $20, but if you pay $500.00 for a 32v3, I think you got a lot of rig (and fun) for the money. The same money gets you an old crappy plastic rice box. Pay $3000.00 for a 30k-1 or some other bigger rig, and you have a lot of fun for the money, people spend that on little plastic boxes that put out 25 or 50 watts! For a lot of guys, playing with the equipment is as much fun as yakking into it. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Coleman Sent: Tuesday, September 28, 2004 7:08 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home Brew
Larry, Maybe, I would have to ask. He and a friend bought a truck load of RCA iron, and its stored in his garage. I am not sure who has what iron left to sell, but I know he wants it out of his garage. It would be pick up only in South Jersey. Price is around $200.00 I would guess, these are NEW transformers in the original crates, although some have some surface rust after 50 years. He has plenty of power transformers as well, but only 220 volt ones left I think. The mod trans would work very well with 813's into 813's. I will call him and ask about the iron... Brett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Larry Roohr Sent: Thursday, September 30, 2004 8:46 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew Hi Brett, Would your friend with the full garage be interested in selling a mod transformer? I've been slowly gathering parts for an 2-813 by 2-813 transmitter and would be interested if he is. Thanks, Larry Brett gazdzinski wrote: A very good choice! Build it right, and it works like a Swiss watch, and is quiet, no fans or blowers needed. 250 to 300 watts out easy, with plenty of audio to go with the carrier. The tubes are easy to find and cheap, there were many surplus transformers that would power the setup nicely, mod transformer size is reasonable. Fair radio used to sell a Collins solder sealed power transformer that would give about 1000 volts at 600 ma full wave center tapped choke input, small size, 110 or 220 volt primary, used to go for $30.00! Variac it and it does 0 to 1500 volts, and will do the rf and mod decks if you want to keep things really simple. I have tried 812a's, 811a's, 572b's in the rf deck, and they all work fine and act the same as far as modulation, drive, and power output go. I have 3 old RCA mod transformers that work with this combo very well, and also work well with the pair of 813's and 4x150a's. 10,500 to 4350 ohms I think they are, and large! They are around, a friend has a garage full of them. I retired the cvm5, as the freq response was quite poor. Building a homebrew rig is incredibly fun, and quite a source of pride if you take the time to build it RIGHT so it works trouble free for years and years, and looks nice. To get parts, you have to network hams, look on ebay, go to fests, buy old homebrew pieces of crap for the parts, and use some of the vendors that sell rf stuff. Even building receivers has not been a problem for me, parts are around, you just have to dig for them instead of going to one place like in the old days. Often, the prices are very reasonable, I picked up a bunch of nice oil filled caps for $10.00 each at Gaithersburg fest last year. I got about 6 of them. They still make new ones, but they wanted $120.00 each! The two big fun points are the chassis chess part, where you Figure out just where things are going, and how you are going to keep things symmetrical, rf and front panel, and the initial testing. Building something, and firing it up and finding it works great is quite fun, and the fun continues every time you use the rig. It also gives plenty to talk about, there is not a lot to say about a rice box into an amp. Old vintage ham gear like Johnson 500, Collins 30k-1, globe king 400/500, and military surplus like the T368, art13, and others can be fun to play with, and sometimes turn up at reasonable prices (but not on ebay). 80 meter night time is hard to break into, and needs good power levels, but 40 in the daytime is very friendly and you can do nicely with 100 watts and up. Valliant's, the Collins 32v series, dx100's, and others in that power class do very well on 40 meters, are fun to play with, and can be got at reasonable prices. People think they are expensive because they used to get them at fests for $10 or $20, but if you pay $500.00 for a 32v3, I think you got a lot of rig (and fun) for the money. The same money gets you an old crappy plastic rice box. Pay $3000.00 for a 30k-1 or some other bigger rig, and you have a lot of fun for the money, people spend that on little plastic boxes that put out 25 or 50 watts! For a lot of guys, playing with the equipment is as much fun as yakking into it. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Coleman Sent: Tuesday, September 28, 2004 7:08 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO __ AMRadio mailing list Home: http
RE: [AMRadio] Home Brew
Brett, If your friend needs to move some of the iron out, I'd be happy to buy a mod transformer. I'm located in Cherry Hill. Thanks and 73, Ed N3CMI Brett gazdzinski Brett.gazdzinski @mci.com To Sent by: 'Discussion of AM Radio' [EMAIL PROTECTED] amradio@mailman.qth.net ailman.qth.net cc Subject 09/30/2004 10:43 RE: [AMRadio] Home Brew AM Please respond to Discussion of AM Radio [EMAIL PROTECTED] qth.net Larry, Maybe, I would have to ask. He and a friend bought a truck load of RCA iron, and its stored in his garage. I am not sure who has what iron left to sell, but I know he wants it out of his garage. It would be pick up only in South Jersey. Price is around $200.00 I would guess, these are NEW transformers in the original crates, although some have some surface rust after 50 years. He has plenty of power transformers as well, but only 220 volt ones left I think. The mod trans would work very well with 813's into 813's. I will call him and ask about the iron... Brett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Larry Roohr Sent: Thursday, September 30, 2004 8:46 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew Hi Brett, Would your friend with the full garage be interested in selling a mod transformer? I've been slowly gathering parts for an 2-813 by 2-813 transmitter and would be interested if he is. Thanks, Larry Brett gazdzinski wrote: A very good choice! Build it right, and it works like a Swiss watch, and is quiet, no fans or blowers needed. 250 to 300 watts out easy, with plenty of audio to go with the carrier. The tubes are easy to find and cheap, there were many surplus transformers that would power the setup nicely, mod transformer size is reasonable. Fair radio used to sell a Collins solder sealed power transformer that would give about 1000 volts at 600 ma full wave center tapped choke input, small size, 110 or 220 volt primary, used to go for $30.00! Variac it and it does 0 to 1500 volts, and will do the rf and mod decks if you want to keep things really simple. I have tried 812a's, 811a's, 572b's in the rf deck, and they all work fine and act the same as far as modulation, drive, and power output go. I have 3 old RCA mod transformers that work with this combo very well, and also work well with the pair of 813's and 4x150a's. 10,500 to 4350 ohms I think they are, and large! They are around, a friend has a garage full of them. I retired the cvm5, as the freq response was quite poor. Building a homebrew rig is incredibly fun, and quite a source of pride if you take the time to build it RIGHT so it works trouble free for years and years, and looks nice. To get parts, you have to network hams, look on ebay, go to fests, buy old homebrew pieces of crap for the parts, and use some of the vendors that sell rf stuff. Even building receivers has not been a problem for me, parts are around, you just have to dig for them instead of going to one place like in the old days. Often, the prices are very reasonable, I picked up a bunch of nice oil filled caps for $10.00 each at Gaithersburg fest last year. I got about 6 of them. They still make new ones, but they wanted $120.00 each! The two big fun points are the chassis chess part, where you Figure out just where things are going, and how you are going to keep things symmetrical, rf and front panel, and the initial testing. Building something, and firing it up and finding it works great is quite fun, and the fun continues every time you use the rig. It also gives plenty to talk about, there is not a lot to say about a rice box into an amp. Old vintage ham gear like Johnson 500, Collins 30k-1, globe king 400/500, and military
RE: [AMRadio] Home brew AM
That would be hard, but not impossible. You would need to read up on mod transformer construction, find something to use as a core, and wind loads of wire on it, keeping in mind the very high voltages that it would have to withstand. You can buy mod transformers, peter dahl makes new ones, ebay, etc. Old surplus is best, old military rigs, broadcast rigs, old ham rigs... I am using mod transformers that were built by RCA in the 1940's for some sort of ship board radio for the Dutch navy I have been told. Without any mod iron, you would have to go to some sort of screen modulation with large tubes. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of GGLL Sent: Wednesday, September 29, 2004 7:55 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home brew AM Hello people, I agree with the nice look and smell of glass AM. Few years ago, I made my CW/AM transmitter, with an 807 plate/screen modulated, 50 watts CW, 40 watts AM output. Started with a triode/pentode oscillator/doubler VFO, then converted to solid state oscillator/buffer, followed by a tube driver (6BQ5) and finally the 807 to a pi tank output. Making my own plate modulated transmitter (200..300 watts out) is a buzzing idea in my mind since a couple of months. But here the most difficult item to get is the modulation transformer, does someone know a method to build it by myself?. Many thanks in advance Best regards Guillermo - LU8EYW. Brett gazdzinski escribió: Steve, What do you need, everything? Here's a partial list of what you need: 3 Chassis 17x3x14, 3 panels 19x10.25?, 3 sets of side supports, Power transformer to give 1500 volts at 500 plus ma, Choke at 500 plus ma, two is better, swinging for the modulator, Rectifiers (I like the k2aw? bricks), Modulation transformer, Bleeder resistors, Big relay and time delay relay for step start if you go that route, 4 Tube sockets, Filament transformers, Killowatt plug in tank coils and its socket and swinging link, Push pull grid coils for the bands wanted, Push pull grid tuning cap (150 to 200 pf per section, low voltage) Modulator grid drive transformer 8 to 10,000 ohms roughly at 20 or more watts, 2 Neutralizing caps, 4 811a tubes, Grid leak resistor (big wire wound pot works well), Insulated shaft couplings, Plate tuning cap, dual 100 pf 5000 volts or better, Meters for grid current, mod current, plate voltage, plate current, A large pile of wire, high voltage wire, screws, nuts, knobs, connector strips, line cord, switches, lights, panel bushings,fuse and holder or breaker, spacers, ceramic standoffs, rf connectors, etc. I could give you some stuff, and sell you some stuff most likely, and MIGHT be able to get you a mod transformer. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, September 29, 2004 9:52 AM To: amradio@mailman.qth.net Subject: [AMRadio] Home brew AM Thanks for the replies. The 812/811 combo was sorta what I had in mind. Getting the components shouldn't be too hard if I keep searching. Let me start here...anyone have any suitable parts? About the E class...read a few things about it...sounds most interesting...but MOSFETS don't have the fragrance of warm vacuum tubes on a chilly winters evening nor the soft orange glow cast through the rig perforations onto the shack walls to keep one company...nor the humming vibrations of pumped RF being piped to the outside antenna. 73 Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home brew AM
Fall Hamfest at the Collins Radio Center, throughout the month of 2004 Liquidation of Heavy iron, test equipment, large variables, 1KW coils with butterfly capacitors, large transmitting tubes, too many items to list. No shipping. No reasonable offer refused. If you plan on stopping by to see the museum and look over the cache, let me know when you will be arriving. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com Nets: 3805 Khz, Monday/Wednesdays 8 PM EDST 14250 Khz Saturday, 12 Noon EDST
Re: [AMRadio] Home brew AM
One option that isn't discussed often because it is considered inefficient at high power is series cathode modulation. This is accomplished by putting the modulator tube between the RF amplifier tube's cathode and ground. The only apparent inefficiency is that you run the RF amp at one fourth of it's Class C CW power rating. I'm currently considering building such a rig using a 450TH for the RF amp and another 450TH for the modulator. At 4500V, the 450TH is good for about 1500W out on CW, and with the modulator tube added will drop to about 375W of carrier. On modulation peaks it will hit the tubes CW power level of 1500W. The tube will be doing fairly light duty at this power level since it can handle 1500W CCS output at 4500V, and should last a very long time as a result. Based on the price and weight of 450TH's vs. large mod transformers, I think it's a good trade off. In addition, the fidelity and audio response will be limited primarily by the audio driver, not the mod transformer. On the negative side, I have to run the plates at 4500V vs. about 2500V for plate modulation. The filament transformer for the RF amp will also need to be hi-pot tested to 4500-5000V (anyone willing to part with a pair of 7.5V, 12A filament transformers that will work for this?). Any thoughts and advice on this approach will be appreciated. Clay W7CE - Original Message - From: Brett gazdzinski [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Thursday, September 30, 2004 9:03 AM Subject: RE: [AMRadio] Home brew AM That would be hard, but not impossible. You would need to read up on mod transformer construction, find something to use as a core, and wind loads of wire on it, keeping in mind the very high voltages that it would have to withstand. You can buy mod transformers, peter dahl makes new ones, ebay, etc. Old surplus is best, old military rigs, broadcast rigs, old ham rigs... I am using mod transformers that were built by RCA in the 1940's for some sort of ship board radio for the Dutch navy I have been told. Without any mod iron, you would have to go to some sort of screen modulation with large tubes. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of GGLL Sent: Wednesday, September 29, 2004 7:55 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home brew AM Hello people, I agree with the nice look and smell of glass AM. Few years ago, I made my CW/AM transmitter, with an 807 plate/screen modulated, 50 watts CW, 40 watts AM output. Started with a triode/pentode oscillator/doubler VFO, then converted to solid state oscillator/buffer, followed by a tube driver (6BQ5) and finally the 807 to a pi tank output. Making my own plate modulated transmitter (200..300 watts out) is a buzzing idea in my mind since a couple of months. But here the most difficult item to get is the modulation transformer, does someone know a method to build it by myself?. Many thanks in advance Best regards Guillermo - LU8EYW. Brett gazdzinski escribió: Steve, What do you need, everything? Here's a partial list of what you need: 3 Chassis 17x3x14, 3 panels 19x10.25?, 3 sets of side supports, Power transformer to give 1500 volts at 500 plus ma, Choke at 500 plus ma, two is better, swinging for the modulator, Rectifiers (I like the k2aw? bricks), Modulation transformer, Bleeder resistors, Big relay and time delay relay for step start if you go that route, 4 Tube sockets, Filament transformers, Killowatt plug in tank coils and its socket and swinging link, Push pull grid coils for the bands wanted, Push pull grid tuning cap (150 to 200 pf per section, low voltage) Modulator grid drive transformer 8 to 10,000 ohms roughly at 20 or more watts, 2 Neutralizing caps, 4 811a tubes, Grid leak resistor (big wire wound pot works well), Insulated shaft couplings, Plate tuning cap, dual 100 pf 5000 volts or better, Meters for grid current, mod current, plate voltage, plate current, A large pile of wire, high voltage wire, screws, nuts, knobs, connector strips, line cord, switches, lights, panel bushings,fuse and holder or breaker, spacers, ceramic standoffs, rf connectors, etc. I could give you some stuff, and sell you some stuff most likely, and MIGHT be able to get you a mod transformer. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, September 29, 2004 9:52 AM To: amradio@mailman.qth.net Subject: [AMRadio] Home brew AM Thanks for the replies. The 812/811 combo was sorta what I had in mind. Getting the components shouldn't be too hard if I keep searching. Let me start here...anyone have any suitable parts? About the E class...read a few things about it...sounds most interesting...but MOSFETS don't have the fragrance of warm vacuum tubes on a chilly winters evening nor the soft orange glow cast
RE: [AMRadio] Home Brew
I figured lots of people would ask... I don't know how many mod transformers they have left to sell, if any. Loads of big 220 to high voltage power transformers, no 110 to high voltage transformers left last time I checked. I will call and see what is up... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 12:02 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Home Brew Brett, If your friend needs to move some of the iron out, I'd be happy to buy a mod transformer. I'm located in Cherry Hill. Thanks and 73, Ed N3CMI Brett gazdzinski Brett.gazdzinski @mci.com To Sent by: 'Discussion of AM Radio' [EMAIL PROTECTED] amradio@mailman.qth.net ailman.qth.net cc Subject 09/30/2004 10:43 RE: [AMRadio] Home Brew AM Please respond to Discussion of AM Radio [EMAIL PROTECTED] qth.net Larry, Maybe, I would have to ask. He and a friend bought a truck load of RCA iron, and its stored in his garage. I am not sure who has what iron left to sell, but I know he wants it out of his garage. It would be pick up only in South Jersey. Price is around $200.00 I would guess, these are NEW transformers in the original crates, although some have some surface rust after 50 years. He has plenty of power transformers as well, but only 220 volt ones left I think. The mod trans would work very well with 813's into 813's. I will call him and ask about the iron... Brett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Larry Roohr Sent: Thursday, September 30, 2004 8:46 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew Hi Brett, Would your friend with the full garage be interested in selling a mod transformer? I've been slowly gathering parts for an 2-813 by 2-813 transmitter and would be interested if he is. Thanks, Larry Brett gazdzinski wrote: A very good choice! Build it right, and it works like a Swiss watch, and is quiet, no fans or blowers needed. 250 to 300 watts out easy, with plenty of audio to go with the carrier. The tubes are easy to find and cheap, there were many surplus transformers that would power the setup nicely, mod transformer size is reasonable. Fair radio used to sell a Collins solder sealed power transformer that would give about 1000 volts at 600 ma full wave center tapped choke input, small size, 110 or 220 volt primary, used to go for $30.00! Variac it and it does 0 to 1500 volts, and will do the rf and mod decks if you want to keep things really simple. I have tried 812a's, 811a's, 572b's in the rf deck, and they all work fine and act the same as far as modulation, drive, and power output go. I have 3 old RCA mod transformers that work with this combo very well, and also work well with the pair of 813's and 4x150a's. 10,500 to 4350 ohms I think they are, and large! They are around, a friend has a garage full of them. I retired the cvm5, as the freq response was quite poor. Building a homebrew rig is incredibly fun, and quite a source of pride if you take the time to build it RIGHT so it works trouble free for years and years, and looks nice. To get parts, you have to network hams, look on ebay, go to fests, buy old homebrew pieces of crap for the parts, and use some of the vendors that sell rf stuff. Even building receivers has not been a problem for me, parts are around, you just have to dig for them instead of going to one place like in the old days. Often, the prices are very reasonable, I picked up a bunch of nice oil filled caps for $10.00 each at Gaithersburg fest last year. I got about 6 of them. They still make new ones, but they wanted $120.00 each! The two big fun points
RE: [AMRadio] Home Brew
From Brad KB7FQR I could not tell who has the BTA 500 1R1 etc, I am intrested to chat with you. I am an tube collector who has been out of the hobby for years and have gotten back in with both feet. I have a Johnson 500 and want to build a 4-1000 amp or other. My motto is NO GLOW NO GO I am in the process of getting a Gates BT5 and looking for other broadcast transmitters on the West coast. I live in N Nevada, have 6 acres and room to store a 50 kw if i can find one. I am new to the site, I am impressed at the quality of hobbyist encountered. NOT APPLIANCE OPERATORS. Best regards to all Brad -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Neal Newman Sent: Wednesday, September 29, 2004 6:06 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew Hey Pete I know that... thats why I have in my collection an RCA BTA-500r,1R1,gates BC-1H, Collins 300G LOL... peter A Markavage wrote: But Class E transmitters don't glow in the dark. You have to put Xmas lights in them. Parts are not that difficult to find if you're willing to spend the time to find them. To me, Class E (asy) lacks the traditional nostalgia that many of us feel in a tube-based transmitter. As someone already pointed out, there are lots of great circuits in the older ARRL Handbooks, Radio and Engineers' Handbook, etc. The ARRL has a new book just out called RF Amplifier Classics and includes two-dozen projects and articles from the pages of QST and QEX, published between 1980 and 2003. There are amps for HF, MF, VHF and microwave. Pete, wa2cwa On Tue, 28 Sep 2004 19:10:27 -0400 Neal Newman [EMAIL PROTECTED] writes: Build a Class E transmitter. Parts for building a tube transmitter is getting harder to find everyday... [EMAIL PROTECTED] wrote: Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home Brew
Thanks for checking, Brett. I'll take a mod transformer and possibly a 220 to HV plate transformer too. 73, Ed N3CMI Brett gazdzinski Brett.gazdzinski @mci.com To Sent by: 'Discussion of AM Radio' [EMAIL PROTECTED] amradio@mailman.qth.net ailman.qth.net cc Subject 09/30/2004 01:03 RE: [AMRadio] Home Brew PM Please respond to Discussion of AM Radio [EMAIL PROTECTED] qth.net I figured lots of people would ask... I don't know how many mod transformers they have left to sell, if any. Loads of big 220 to high voltage power transformers, no 110 to high voltage transformers left last time I checked. I will call and see what is up... Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, September 30, 2004 12:02 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Home Brew Brett, If your friend needs to move some of the iron out, I'd be happy to buy a mod transformer. I'm located in Cherry Hill. Thanks and 73, Ed N3CMI Brett gazdzinski Brett.gazdzinski @mci.com To Sent by: 'Discussion of AM Radio' [EMAIL PROTECTED] amradio@mailman.qth.net ailman.qth.net cc Subject 09/30/2004 10:43 RE: [AMRadio] Home Brew AM Please respond to Discussion of AM Radio [EMAIL PROTECTED] qth.net Larry, Maybe, I would have to ask. He and a friend bought a truck load of RCA iron, and its stored in his garage. I am not sure who has what iron left to sell, but I know he wants it out of his garage. It would be pick up only in South Jersey. Price is around $200.00 I would guess, these are NEW transformers in the original crates, although some have some surface rust after 50 years. He has plenty of power transformers as well, but only 220 volt ones left I think. The mod trans would work very well with 813's into 813's. I will call him and ask about the iron... Brett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Larry Roohr Sent: Thursday, September 30, 2004 8:46 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew Hi Brett, Would your friend with the full garage be interested in selling a mod transformer? I've been slowly gathering parts for an 2-813 by 2-813 transmitter and would be interested if he is. Thanks, Larry Brett gazdzinski wrote: A very good choice! Build it right, and it works like a Swiss watch, and is quiet, no fans or blowers needed. 250 to 300 watts out easy, with plenty of audio to go with the carrier. The tubes are easy to find and cheap, there were many surplus transformers that would power the setup nicely, mod transformer size is reasonable. Fair radio used to sell a Collins solder sealed power transformer that would give about 1000 volts at 600 ma full wave center tapped choke input, small size, 110 or 220 volt primary, used to go for $30.00! Variac it and it does 0 to 1500 volts, and will do the rf and mod decks if you want to keep things really simple. I have tried 812a's, 811a's, 572b's in the rf deck, and they all work fine and act the same as far as modulation, drive, and power output go. I have 3 old RCA mod transformers that work with this combo very well, and also work well with the pair of 813's and 4x150a's. 10,500 to 4350 ohms I think they are, and large! They are around, a friend has a garage full of them. I retired the cvm5
Re: [AMRadio] Home Brew
Hello Brad. I think your Looking to talk with Me I also collect old FM broadcast transmitters... Neal Newman-KA2CAF CE/CO WTTM,WYGG,WUPC,W220AA http://www.angelfire.com/nj4/wttm UVC wrote: From Brad KB7FQR I could not tell who has the BTA 500 1R1 etc, I am intrested to chat with you. I am an tube collector who has been out of the hobby for years and have gotten back in with both feet. I have a Johnson 500 and want to build a 4-1000 amp or other. My motto is NO GLOW NO GO I am in the process of getting a Gates BT5 and looking for other broadcast transmitters on the West coast. I live in N Nevada, have 6 acres and room to store a 50 kw if i can find one. I am new to the site, I am impressed at the quality of hobbyist encountered. NOT APPLIANCE OPERATORS. Best regards to all Brad -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Neal Newman Sent: Wednesday, September 29, 2004 6:06 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew Hey Pete I know that... thats why I have in my collection an RCA BTA-500r,1R1,gates BC-1H, Collins 300G LOL... peter A Markavage wrote: But Class E transmitters don't glow in the dark. You have to put Xmas lights in them. Parts are not that difficult to find if you're willing to spend the time to find them. To me, Class E (asy) lacks the traditional nostalgia that many of us feel in a tube-based transmitter. As someone already pointed out, there are lots of great circuits in the older ARRL Handbooks, Radio and Engineers' Handbook, etc. The ARRL has a new book just out called RF Amplifier Classics and includes two-dozen projects and articles from the pages of QST and QEX, published between 1980 and 2003. There are amps for HF, MF, VHF and microwave. Pete, wa2cwa On Tue, 28 Sep 2004 19:10:27 -0400 Neal Newman [EMAIL PROTECTED] writes: Build a Class E transmitter. Parts for building a tube transmitter is getting harder to find everyday... [EMAIL PROTECTED] wrote: Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home brew AM
David where are you located?? David Knepper wrote: Fall Hamfest at the Collins Radio Center, throughout the month of 2004 Liquidation of Heavy iron, test equipment, large variables, 1KW coils with butterfly capacitors, large transmitting tubes, too many items to list. No shipping. No reasonable offer refused. If you plan on stopping by to see the museum and look over the cache, let me know when you will be arriving. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com Nets: 3805 Khz, Monday/Wednesdays 8 PM EDST 14250 Khz Saturday, 12 Noon EDST __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home brew AM
A few miles east of Johnstown, PA Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com Nets: 3805 Khz, Monday/Wednesdays 8 PM EDST 14250 Khz Saturday, 12 Noon EDST - Original Message - From: Neal Newman [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Thursday, September 30, 2004 4:03 PM Subject: Re: [AMRadio] Home brew AM David where are you located?? David Knepper wrote: Fall Hamfest at the Collins Radio Center, throughout the month of 2004 Liquidation of Heavy iron, test equipment, large variables, 1KW coils with butterfly capacitors, large transmitting tubes, too many items to list. No shipping. No reasonable offer refused. If you plan on stopping by to see the museum and look over the cache, let me know when you will be arriving. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com Nets: 3805 Khz, Monday/Wednesdays 8 PM EDST 14250 Khz Saturday, 12 Noon EDST __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home Brew
You might want to look at ebay. There is a 2kw home brew that looks like nice mechanical, but no modulator. Byron
Re: [AMRadio] Home Brew
I am trying to figure out how to cathode modulate the 4-1000 I have. I have a pair of 813's and have a 4-125. Have a bunch of 807's and 1625's as well. Joe W4AAB - Original Message - From: [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Tuesday, September 28, 2004 6:47 PM Subject: Re: [AMRadio] Home Brew There are all kinds of good designs in the 50's handbooks. The most fun you will have is trying to find all the parts. 73, John, W4AWM I'd like to build my own AM transmitter. Tube style; more than 200 watts. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home Brew
Here you go - it sounds simple. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John Coleman Sent: Tuesday, September 28, 2004 7:08 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, September 28, 2004 2:50 PM To: amradio@mailman.qth.net Subject: [AMRadio] Home Brew Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home Brew
Joe, If you are going to cathode modulate that 4X1... Consider PDM Digital. You will need twice the plate voltage +20% if you want 120% positive peak audio capability. The 4-125 is the only tube in your list that can possibly hold off the voltage and it's close at that. FYI: I am finishing up a Class-D 4-1000 PDM modulator for my 4-1000 Class C stage. It's a series modulator that will feed the 4-1000 class C plate and is unique, with a floating cathode pulsed at 110KHz at 7KV. I call it high-side-PDM. This way a conventional RF deck can be PLATE MODULATED. The grid switcher uses FETS, and the screen supply also floats at the 7KV level. Optical coupling is used to get the PDM stream to the grid fets. If you are interested in such a crazy project, let me know. It will be nice to have digital audio from the class C 4X1 on 80-10 Meters... If it works and I survive the testing process (scared). The rig will be called 4X1X4X1 George AB2KC. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Crawfish Sent: Tuesday, September 28, 2004 11:19 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew I am trying to figure out how to cathode modulate the 4-1000 I have. I have a pair of 813's and have a 4-125. Have a bunch of 807's and 1625's as well. Joe W4AAB - Original Message - From: [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Tuesday, September 28, 2004 6:47 PM Subject: Re: [AMRadio] Home Brew There are all kinds of good designs in the 50's handbooks. The most fun you will have is trying to find all the parts. 73, John, W4AWM I'd like to build my own AM transmitter. Tube style; more than 200 watts. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home Brew
If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. I have parts of an old homebrew 10 meter AM transmitter and it looks like this is what he did too, only using 811s in the finals as well as modulators. Probably the simplest/cheapest way to get some power back in the early 50s. 73, Bob W9RAN
RE: [AMRadio] Home Brew
It sounds simple, and the RF stuff is simple, but it's the control and metering that adds complexity. Step start, push to talk, grid current and voltage metering, plate or cathode current and plate voltage meters, plate voltage control (variac or power trans primary taps),filiment voltage control and metering, protective bias plus grid leak bias, etc. But overall, it is quite simple, one step at a time... I like building a small deck just for the rf, and do the control on a separate deck, with lots of meters and knobs to twist. Big wire wound pots work great for grid leak resistors. Add in control grids and it gets more complex, with sequence starting, more power supplies and metering, overload circuits, etc. Its loads of fun to figure out what will work with what parts you have or can get. On the subject of meters (I use a lot of them), I use the cheap radio shack meters, they used to make 0-15 volts, 0-500 ma, and 0 to 1ma meters that took a very small hole in the panel. I just make the scales indicate whatever I want, 0-15 volts can be 0 to 150 volts, 0 to 1500 volts, 1.5 amps, 150 ma, etc. The scales come off, they are held on with glue, and you can make up your own numbers or transfer them from one meter to another, as I think they only sell the 0-15 volt meter now. I should use a computer program to make up real scales. So you can have a load of meters, all the same, cheap cost, small panel holes, and modern looking. Shunts will give any current you want, voltage dividers give whatever voltage you want. Black painted panels with P touch labels looks nice, and don't count on remembering what meter does what, or where its supposed to read after 10 years or more, or the next guy who gets the equipment! You can mark the correct voltage/current with a red felt tip marker. A pair of 813's takes how much grid drive? Screen current? Where did you run the plate current on the 4d32 rig? Are the 4x150a filaments 6 volts, or 6.3? Is this stuff fun or what? Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Schichler, Don Sent: Wednesday, September 29, 2004 8:33 AM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home Brew Here you go - it sounds simple. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of John Coleman Sent: Tuesday, September 28, 2004 7:08 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, September 28, 2004 2:50 PM To: amradio@mailman.qth.net Subject: [AMRadio] Home Brew Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home Brew
Nothing wrong with that! You can go to just grid leak bias with the 811a's, or 572b's. 812a's are THEORETICALLY supposed to me better under modulation, but I could tell no difference in peak modulation, distortion, etc, between the 811a and 812a tubes (with plenty of grid leak bias). Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Robert Nickels Sent: Wednesday, September 29, 2004 9:04 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Home Brew If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. I have parts of an old homebrew 10 meter AM transmitter and it looks like this is what he did too, only using 811s in the finals as well as modulators. Probably the simplest/cheapest way to get some power back in the early 50s. 73, Bob W9RAN __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Home brew AM
Thanks for the replies. The 812/811 combo was sorta what I had in mind. Getting the components shouldn't be too hard if I keep searching. Let me start here...anyone have any suitable parts? About the E class...read a few things about it...sounds most interesting...but MOSFETS don't have the fragrance of warm vacuum tubes on a chilly winters evening nor the soft orange glow cast through the rig perforations onto the shack walls to keep one company...nor the humming vibrations of pumped RF being piped to the outside antenna. 73 Steve WA2TAK
[AMRadio] Home Brew
Hi Guys: You're all really great - I sure need this help. My last home brew was an 807 CW xmtr back in 1963 when I got my novice license...just got it back 18 months ago after being QRX for 40 years. There's many ways to go - component wise - so let me express my 'view' of the rig. I like simple - very simple - most simple, like minimalist...as opposed to having features, bells whistles. Style-wise, I'd like to use nice, shinny vintage parts...with contemporary materials...rather than try to get the neovintage look. The pictures I've seen on some Eclass rigs appeals to me...clean and neat looking. Don't know if I'd like the Amp Mod separate units or stacked. Stacked in a single enclosure sounds easy mechanically...and little less work? Not having fans/blowers seems to be a good operating advantage with less interfering noise. Seems like the replies are 'amp-minded' rather than complete high power AM transmitter..which gets to the matter of the exciter. I'm presently completing my DX100 ala GTO ( Fire Enginer red w/ chrome ) restoration...might I be able to put the MODAMP into a DX100 enclosure?? Make a nice looking set...but might be a bit too tight? Tnx, Steve WA2TAK
RE: [AMRadio] Home Brew
Steve, Hi Guys: You're all really great - I sure need this help. My last home brew was an 807 CW xmtr back in 1963 when I got my novice license...just got it back 18 months ago after being QRX for 40 years. There's many ways to go - component wise - so let me express my 'view' of the rig. I like simple - very simple - most simple, like minimalist...as opposed to having features, bells whistles. You cant get to simple, as you need to know what's going on, and to prevent problems, and allow adjustments. You need meters. Style-wise, I'd like to use nice, shinny vintage parts...with contemporary materials...rather than try to get the neovintage look. The pictures I've seen on some Eclass rigs appeals to me...clean and neat looking. I only use nice looking parts. I paint my chassis grey, use nice clean ceramics, put chrome handles on the front panels, use all the same older style knobs, etc. Going old looking with nice bits will be very expensive, and take a long time to get all those rare matching bits in good shape. Don't know if I'd like the Amp Mod separate units or stacked. Stacked in a single enclosure sounds easy mechanically...and little less work? Rf deck and modulator? I like separate decks, easier to build, test, change, and fit the parts. I rack mount everything, heavy iron can sit on the cabinet floor. I use rails so the decks slide out, you can make your own. Not having fans/blowers seems to be a good operating advantage with less interfering noise. Its nice having a SILENT rig. I have both, and silent is very nice. Seems like the replies are 'amp-minded' rather than complete high power AM transmitter.. which gets to the matter of the exciter. I'm presently completing my DX100 ala GTO ( Fire Enginer red w/ chrome ) restoration...might I be able to put the MODAMP into a DX100 enclosure?? Mod and RF deck. No, not at 200 watts plus out. Even with the power supply/supplies separate, you would not be able to fit a pair of 811a tubes in push pull rf service and the modulator into a DX100 cabinet. Just the RF deck will be DX100 size, reference Bill Orr or old ARRL handbooks. Unless you get very creative and run things very light, figure on each deck being dx100 size. Make a nice looking set...but might be a bit too tight? For a 300 watt rig, you need bigger parts and space to fit them. Ever see a globe king 400 or 500? Three decks, power supply, mod deck, and RF deck. And the globe king equipment was built very light for the power. The dx100 is fairly compact, so figure it's a 100 watt size. 200 watts would be twice as big and heavy, 300 watts three times... Short of class E, there is no way around this rule. Good stuff and broadcast rigs are even bigger and heavier for the same power output. Modern amps are different, no modulator, light duty power supply, much lower peak voltages. You can pick up nice racks for nothing, stop by South Jersey and you can take your pick of a bunch of racks in nice shape, from 4 to 6 feet high. Free if you haul them away. Tnx, Steve WA2TAK Brett N2DTS __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home brew AM
Steve, What do you need, everything? Here's a partial list of what you need: 3 Chassis 17x3x14, 3 panels 19x10.25?, 3 sets of side supports, Power transformer to give 1500 volts at 500 plus ma, Choke at 500 plus ma, two is better, swinging for the modulator, Rectifiers (I like the k2aw? bricks), Modulation transformer, Bleeder resistors, Big relay and time delay relay for step start if you go that route, 4 Tube sockets, Filament transformers, Killowatt plug in tank coils and its socket and swinging link, Push pull grid coils for the bands wanted, Push pull grid tuning cap (150 to 200 pf per section, low voltage) Modulator grid drive transformer 8 to 10,000 ohms roughly at 20 or more watts, 2 Neutralizing caps, 4 811a tubes, Grid leak resistor (big wire wound pot works well), Insulated shaft couplings, Plate tuning cap, dual 100 pf 5000 volts or better, Meters for grid current, mod current, plate voltage, plate current, A large pile of wire, high voltage wire, screws, nuts, knobs, connector strips, line cord, switches, lights, panel bushings,fuse and holder or breaker, spacers, ceramic standoffs, rf connectors, etc. I could give you some stuff, and sell you some stuff most likely, and MIGHT be able to get you a mod transformer. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, September 29, 2004 9:52 AM To: amradio@mailman.qth.net Subject: [AMRadio] Home brew AM Thanks for the replies. The 812/811 combo was sorta what I had in mind. Getting the components shouldn't be too hard if I keep searching. Let me start here...anyone have any suitable parts? About the E class...read a few things about it...sounds most interesting...but MOSFETS don't have the fragrance of warm vacuum tubes on a chilly winters evening nor the soft orange glow cast through the rig perforations onto the shack walls to keep one company...nor the humming vibrations of pumped RF being piped to the outside antenna. 73 Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home Brew
Hey Pete I know that... thats why I have in my collection an RCA BTA-500r,1R1,gates BC-1H, Collins 300G LOL... peter A Markavage wrote: But Class E transmitters don't glow in the dark. You have to put Xmas lights in them. Parts are not that difficult to find if you're willing to spend the time to find them. To me, Class E (asy) lacks the traditional nostalgia that many of us feel in a tube-based transmitter. As someone already pointed out, there are lots of great circuits in the older ARRL Handbooks, Radio and Engineers' Handbook, etc. The ARRL has a new book just out called RF Amplifier Classics and includes two-dozen projects and articles from the pages of QST and QEX, published between 1980 and 2003. There are amps for HF, MF, VHF and microwave. Pete, wa2cwa On Tue, 28 Sep 2004 19:10:27 -0400 Neal Newman [EMAIL PROTECTED] writes: Build a Class E transmitter. Parts for building a tube transmitter is getting harder to find everyday... [EMAIL PROTECTED] wrote: Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Home brew AM
Hello people, I agree with the nice look and smell of glass AM. Few years ago, I made my CW/AM transmitter, with an 807 plate/screen modulated, 50 watts CW, 40 watts AM output. Started with a triode/pentode oscillator/doubler VFO, then converted to solid state oscillator/buffer, followed by a tube driver (6BQ5) and finally the 807 to a pi tank output. Making my own plate modulated transmitter (200..300 watts out) is a buzzing idea in my mind since a couple of months. But here the most difficult item to get is the modulation transformer, does someone know a method to build it by myself?. Many thanks in advance Best regards Guillermo - LU8EYW. Brett gazdzinski escribió: Steve, What do you need, everything? Here's a partial list of what you need: 3 Chassis 17x3x14, 3 panels 19x10.25?, 3 sets of side supports, Power transformer to give 1500 volts at 500 plus ma, Choke at 500 plus ma, two is better, swinging for the modulator, Rectifiers (I like the k2aw? bricks), Modulation transformer, Bleeder resistors, Big relay and time delay relay for step start if you go that route, 4 Tube sockets, Filament transformers, Killowatt plug in tank coils and its socket and swinging link, Push pull grid coils for the bands wanted, Push pull grid tuning cap (150 to 200 pf per section, low voltage) Modulator grid drive transformer 8 to 10,000 ohms roughly at 20 or more watts, 2 Neutralizing caps, 4 811a tubes, Grid leak resistor (big wire wound pot works well), Insulated shaft couplings, Plate tuning cap, dual 100 pf 5000 volts or better, Meters for grid current, mod current, plate voltage, plate current, A large pile of wire, high voltage wire, screws, nuts, knobs, connector strips, line cord, switches, lights, panel bushings,fuse and holder or breaker, spacers, ceramic standoffs, rf connectors, etc. I could give you some stuff, and sell you some stuff most likely, and MIGHT be able to get you a mod transformer. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, September 29, 2004 9:52 AM To: amradio@mailman.qth.net Subject: [AMRadio] Home brew AM Thanks for the replies. The 812/811 combo was sorta what I had in mind. Getting the components shouldn't be too hard if I keep searching. Let me start here...anyone have any suitable parts? About the E class...read a few things about it...sounds most interesting...but MOSFETS don't have the fragrance of warm vacuum tubes on a chilly winters evening nor the soft orange glow cast through the rig perforations onto the shack walls to keep one company...nor the humming vibrations of pumped RF being piped to the outside antenna. 73 Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Home Brew
Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve WA2TAK
Re: [AMRadio] Home Brew
Build a Class E transmitter. Parts for building a tube transmitter is getting harder to find everyday... [EMAIL PROTECTED] wrote: Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Home Brew
If I were going to build with tubes again and two hundred watts was the carrier output that I wanted. I would use a pair of 812s in push pull class C and modulate with a pair of 811As push pull class B. Run about 1500 volts @ 200 ma for 300 watts plate input on the 812s. Find a Modulation XFMR to match the output of 811A class B (about 12500 ohms as I remember) to the 7500 ohm class C final. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, September 28, 2004 2:50 PM To: amradio@mailman.qth.net Subject: [AMRadio] Home Brew Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve
Re: [AMRadio] Home Brew
There are all kinds of good designs in the 50's handbooks. The most fun you will have is trying to find all the parts. 73, John, W4AWM I'd like to build my own AM transmitter. Tube style; more than 200 watts.
RE: [AMRadio] Home Brew
Mostly depends on what you can get your hands on. These days, you have to design around what you can get at a reasonable price. As far as tubes go, one or a pair of 813's works VERY well in the RF deck, Pair of 811a or 812a tubes will also do nicely. A 4-125 will work well at 2500 volts. High voltage gets expensive, and the 811/812 tubes work from 1000 volts up to 2000. 813 likes 2000 but works lower. The 4-125, 4-250, and 4-400 tubes like higher voltages. A rice box makes a good RF exciter, and will drive 813's, 812a's, 4-125, etc no problem. For a modulator, KT90 tubes, 811a's, 813,s, 4-xxx will work, The zero bias triodes are easy, no bias, drive the grids with an 8 ohm to 6000 ohm output transformer using some solid state audio amp. Choices are driven by what mod iron you can find, power transformers, chokes, etc. I have a homebrew pair of 813's in pie net 160 to 10 meters Driven by a 4x150 (4cx250b) AB1 mod deck, I have a Push pull pair of 812a's modulated by 811a's, and a pair Of 4D32 tubes in pie net 40 meters only. The old Bill Orr books have lots of good building stuff in them. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, September 28, 2004 3:50 PM To: amradio@mailman.qth.net Subject: [AMRadio] Home Brew Hello All: I'd like to build my own AM transmitter. Tube style; more than 200 watts. Sure a heck of a lot to choose from...but I'd like to hear what you think. OR...if someone knows of a home brew for sale Tnx, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
