RE: [AMRadio] Pictures of homebrew rx, new 4D32 project, other homebrew things
John, Wow, for some reason, when I look at them on your site, they look very good, very large, and the don't fit on my laptop screen, but you can read the labels on things! Thanks for posting them for me. Brett N2DTS > > > Ok Bret your pictures or at > http://wa5bxo.shacknet.nu/N2DTS/ > > CUL, 73 > John, WA5BXO > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > On Behalf Of Brett Gazdzinski > Sent: Friday, January 23, 2004 9:54 AM > To: amradio@mailman.qth.net > Subject: [AMRadio] Pictures of homebrew rx, new 4D32 project, > other homebrew > things > > I have pictures of various things if anyone wants a look, > the jay pegs are big, so beware if you ask to see something. > I burnt them onto a cd so I could unload my lap top hard drive. > > Anyplace I could post these things? > > Brett > N2DTS > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio > > > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] 4D32 rig testing
Dave, many people run them on low voltage, that is ok with me. I have been running mine on the high voltage for 15 years with no crap outs at all, not a single problem with them. The low voltage transformer frequently went because it was overloaded, and removing the vacuum rectifiers reduces the load a lot. peter Dahl sells replacements, they are likely not cheap, but are good transformers. The only mod transformer I ever blew out was in the 30K1 I had, testing it with 20hz at 100% modulation at full power. Stupid, but I did not know anything then, and the 30K1 cost me less than the peter Dahl 32v3 mod transformer ($200.00). Serial number 9, I wonder if its on the air now, it used to sound very good when I sold it to someone down south. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of David Knepper > Sent: Saturday, January 24, 2004 4:10 PM > To: amradio@mailman.qth.net > Subject: Re: [AMRadio] 4D32 rig testing > > > Please excuse my ignorance among the experts but shouldn't > one be careful > not to push the voltage rating on the secondary of the modulation > transformer when increasing the plate voltage on the RF > amplifier? or on the > primary winding when pushing higher voltage on the mod. tubes. > > On all of my 32V's at the Collins Radio Center, I put the > toggle switch on > the rear to 600 volts, not 700 volts. Know where I can get a > replacement > mod. transformer for the 32V transmitter? I don't! > > Inquiring minds would like to know! Why sacrifice a > modulation transformer, > which are expensive and rare these days. > > Thank you > Dave, W3ST > Secretary to the Collins Radio Association > Publisher of the Collins Journal > www.collinsra.com > - Original Message - > From: "Donald Chester" <[EMAIL PROTECTED]> > To: > Sent: Saturday, January 24, 2004 3:47 PM > Subject: RE: [AMRadio] 4D32 rig testing > > > > > > > > >Collins runs them at over 700 volts in class C plate > > >modulated service (32V series). > > >If they don't arc over, and you don't exceed the plate dissipation, > > >what would be the problem? > > > > > > > That's a good point. I recall an article pre-WW2 in QST > which described > > getting high peak audio power from modulator tubes by > running unusually > high > > voltage on them, but staying within the rated dissipation > rating. A point > > was made that for example, the 807 is rated for a maximum > of 600 volts > plate > > modulated. That means the peak voltage would be at least > 1200 volts, and > > that doesn't hurt them, and is still within factory > specified ratings. So > > for intermittent service, you should be able to run as much > as 1200 DC > volts > > on an 807. I think the limit on plate modulated voltage > would be the > point > > where arcovers would begin. > > > > However, I do recall using a quad of p-p parallel 2A3's in my audio > driver. > > I didn't have a proper driver transformer at the time, so I > ran them @ 400 > > volts/30 m.a. each tube. They are rated at 300 volts/40 > m.a. maximum in > the > > RCA manual. That way I could get plenty of peak driving > voltage to the > > class B grids, despite having a driver transformer with too > much stepdown, > > but with exactly the same plate dissipation as per RCA recommended > ratings. > > They worked great, and drove the modulator tubes with very little > > distortion. But I noticed that within a few months, the > 2A3's would get > > weak. I went through a couple of sets that way. Finally, > I obtained a > > proper driver transformer with the proper turns ratio, and > slowered the > > plate voltage back to 300v, and changed the bias so that > each tube would > > draw 40 m.a., and now I have had the same set of 2A3's for almost 10 > years, > > and they still test good. Maybe just a coincidence, but > at the current > > price of a new 2A3, I don't feel like trying to find out. > > > > My conclusion is that some tubes may not take overvoltage > very well, while > > others will not be harmed, and the only way to find out > which ones is to > try > > them and see. If your tubes seem to be short lived, go back to the > > recommended parameters. > > > > -K4KYV > > > > _ > > High-speed users-be more efficient online with the new MSN Premium > Internet > > Software. http://join.msn.com/?pgmarket=en-us&page=byoa/prem&ST=1 > > > > ___ > > AMRadio mailing list > > AMRadio@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/amradio > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] 4D32 rig testing
Don, I was in qso with Jay, n2wwl today, and we were talking about the 32v3, and the voltage it runs at, Jay runs his on the low voltage position, about 600 volts on the plates. I run mine on the 700 volt tap, 180 to 200 ma. The panel meter says 800 volts high voltage, but I put my DMM on it and was very surprised to find 940 volts on the plates. I have been running them that way for 15 years with the same tubes in them, and used to use them quite a lot. I get 100 watts out, and 350 watts pep. I have solid stated the power supplies, which explains the high voltage. I think, as long as you don't exceed the plate dissipation, you are likely ok with most tubes. Brett N2DTS > > > > >Collins runs them at over 700 volts in class C plate > >modulated service (32V series). > >If they don't arc over, and you don't exceed the plate dissipation, > >what would be the problem? > > > > That's a good point. I recall an article pre-WW2 in QST > which described > getting high peak audio power from modulator tubes by running > unusually high > voltage on them, but staying within the rated dissipation > rating. A point > was made that for example, the 807 is rated for a maximum of > 600 volts plate > modulated. That means the peak voltage would be at least > 1200 volts, and > that doesn't hurt them, and is still within factory specified > ratings. So > for intermittent service, you should be able to run as much > as 1200 DC volts > on an 807. I think the limit on plate modulated voltage > would be the point > where arcovers would begin. > > However, I do recall using a quad of p-p parallel 2A3's in my > audio driver. > I didn't have a proper driver transformer at the time, so I > ran them @ 400 > volts/30 m.a. each tube. They are rated at 300 volts/40 m.a. > maximum in the > RCA manual. That way I could get plenty of peak driving > voltage to the > class B grids, despite having a driver transformer with too > much stepdown, > but with exactly the same plate dissipation as per RCA > recommended ratings. > They worked great, and drove the modulator tubes with very little > distortion. But I noticed that within a few months, the > 2A3's would get > weak. I went through a couple of sets that way. Finally, I > obtained a > proper driver transformer with the proper turns ratio, and > slowered the > plate voltage back to 300v, and changed the bias so that each > tube would > draw 40 m.a., and now I have had the same set of 2A3's for > almost 10 years, > and they still test good. Maybe just a coincidence, but at > the current > price of a new 2A3, I don't feel like trying to find out. > > My conclusion is that some tubes may not take overvoltage > very well, while > others will not be harmed, and the only way to find out which > ones is to try > them and see. If your tubes seem to be short lived, go back to the > recommended parameters. > > -K4KYV > > _ > High-speed usersbe more efficient online with the new MSN > Premium Internet > Software. http://join.msn.com/?pgmarket=en-us&page=byoa/prem&ST=1 > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio >
Re: [AMRadio] 4D32 rig testing
Please excuse my ignorance among the experts but shouldn't one be careful not to push the voltage rating on the secondary of the modulation transformer when increasing the plate voltage on the RF amplifier? or on the primary winding when pushing higher voltage on the mod. tubes. On all of my 32V's at the Collins Radio Center, I put the toggle switch on the rear to 600 volts, not 700 volts. Know where I can get a replacement mod. transformer for the 32V transmitter? I don't! Inquiring minds would like to know! Why sacrifice a modulation transformer, which are expensive and rare these days. Thank you Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com - Original Message - From: "Donald Chester" <[EMAIL PROTECTED]> To: Sent: Saturday, January 24, 2004 3:47 PM Subject: RE: [AMRadio] 4D32 rig testing > > > >Collins runs them at over 700 volts in class C plate > >modulated service (32V series). > >If they don't arc over, and you don't exceed the plate dissipation, > >what would be the problem? > > > > That's a good point. I recall an article pre-WW2 in QST which described > getting high peak audio power from modulator tubes by running unusually high > voltage on them, but staying within the rated dissipation rating. A point > was made that for example, the 807 is rated for a maximum of 600 volts plate > modulated. That means the peak voltage would be at least 1200 volts, and > that doesn't hurt them, and is still within factory specified ratings. So > for intermittent service, you should be able to run as much as 1200 DC volts > on an 807. I think the limit on plate modulated voltage would be the point > where arcovers would begin. > > However, I do recall using a quad of p-p parallel 2A3's in my audio driver. > I didn't have a proper driver transformer at the time, so I ran them @ 400 > volts/30 m.a. each tube. They are rated at 300 volts/40 m.a. maximum in the > RCA manual. That way I could get plenty of peak driving voltage to the > class B grids, despite having a driver transformer with too much stepdown, > but with exactly the same plate dissipation as per RCA recommended ratings. > They worked great, and drove the modulator tubes with very little > distortion. But I noticed that within a few months, the 2A3's would get > weak. I went through a couple of sets that way. Finally, I obtained a > proper driver transformer with the proper turns ratio, and slowered the > plate voltage back to 300v, and changed the bias so that each tube would > draw 40 m.a., and now I have had the same set of 2A3's for almost 10 years, > and they still test good. Maybe just a coincidence, but at the current > price of a new 2A3, I don't feel like trying to find out. > > My conclusion is that some tubes may not take overvoltage very well, while > others will not be harmed, and the only way to find out which ones is to try > them and see. If your tubes seem to be short lived, go back to the > recommended parameters. > > -K4KYV > > _ > High-speed users-be more efficient online with the new MSN Premium Internet > Software. http://join.msn.com/?pgmarket=en-us&page=byoa/prem&ST=1 > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] 4D32 rig testing
Collins runs them at over 700 volts in class C plate modulated service (32V series). If they don't arc over, and you don't exceed the plate dissipation, what would be the problem? That's a good point. I recall an article pre-WW2 in QST which described getting high peak audio power from modulator tubes by running unusually high voltage on them, but staying within the rated dissipation rating. A point was made that for example, the 807 is rated for a maximum of 600 volts plate modulated. That means the peak voltage would be at least 1200 volts, and that doesn't hurt them, and is still within factory specified ratings. So for intermittent service, you should be able to run as much as 1200 DC volts on an 807. I think the limit on plate modulated voltage would be the point where arcovers would begin. However, I do recall using a quad of p-p parallel 2A3's in my audio driver. I didn't have a proper driver transformer at the time, so I ran them @ 400 volts/30 m.a. each tube. They are rated at 300 volts/40 m.a. maximum in the RCA manual. That way I could get plenty of peak driving voltage to the class B grids, despite having a driver transformer with too much stepdown, but with exactly the same plate dissipation as per RCA recommended ratings. They worked great, and drove the modulator tubes with very little distortion. But I noticed that within a few months, the 2A3's would get weak. I went through a couple of sets that way. Finally, I obtained a proper driver transformer with the proper turns ratio, and slowered the plate voltage back to 300v, and changed the bias so that each tube would draw 40 m.a., and now I have had the same set of 2A3's for almost 10 years, and they still test good. Maybe just a coincidence, but at the current price of a new 2A3, I don't feel like trying to find out. My conclusion is that some tubes may not take overvoltage very well, while others will not be harmed, and the only way to find out which ones is to try them and see. If your tubes seem to be short lived, go back to the recommended parameters. -K4KYV _ High-speed usersbe more efficient online with the new MSN Premium Internet Software. http://join.msn.com/?pgmarket=en-us&page=byoa/prem&ST=1
RE: [AMRadio] Pictures of homebrew rx, new 4D32 project, other homebrew things
Ok Bret your pictures or at http://wa5bxo.shacknet.nu/N2DTS/ CUL, 73 John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett Gazdzinski Sent: Friday, January 23, 2004 9:54 AM To: amradio@mailman.qth.net Subject: [AMRadio] Pictures of homebrew rx, new 4D32 project, other homebrew things I have pictures of various things if anyone wants a look, the jay pegs are big, so beware if you ask to see something. I burnt them onto a cd so I could unload my lap top hard drive. Anyplace I could post these things? Brett N2DTS ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
[AMRadio] RCA TT-4 transmitting tube manual now online
I am sure this is one of our favorites. I know it is one of mine, so I scanned one of them and here it is for your exquisite pleasure.. Please report any errors, (some pages are slightly crooked, but I am more concerned with omissions, bad links etc) http://208.190.133.201/rcatt4/rcatt4.html
