There was a Rothman circuit, worked well but I would not use it today. The tube in the antenna lead could generate harmonics without a low pass filter, at the band of operation.
Mike was correct, Taylor Modulation did and does exist, dont tell the collectors but I modified an ARC-5 for Taylor. Uses one final, modulated by a single 829B.Not currently on the air but available. 73 Charlie, K0NG Quoting David Knepper <[EMAIL PROTECTED]>: > Wasn't there a commercial modulator using the "Rothman" circuit some years > ago. I remember seeing it somewhere in a catalog. > > > 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: "Geoff/W5OMR" <[EMAIL PROTECTED]> > To: <amradio@mailman.qth.net> > Sent: Wednesday, December 22, 2004 11:24 AM > Subject: [AMRadio] Rothman Modulation > > > > This is a new term, for me. So, a Googling I went. > > > > Not much information on Rothman Modulation, but there was some. > > Perhaps someone else on here can add to this? > > > > 73 = Best Regards, > > -Geoff/W5OMR > > > > -------------------------------------------------------------- > > Article: 101889 of rec.radio.amateur.boatanchors > > From: Edward Knobloch <[EMAIL PROTECTED]> > > Subject: Re: Info needed on "Taylor Modulation" from the 50's. > > References: <[EMAIL PROTECTED]> > > Message-ID: <[EMAIL PROTECTED]> > > Date: Fri, 22 Oct 2004 17:06:49 GMT > > > > Mike Baker <[EMAIL PROTECTED]> wrote: > > > Hello to all. > > > When I was a kid I recall reading something in an old CQ/73/QST > > > magazine about a modulation method for AM called Tayor Modulation. It > > > was sort of a precursor to controlled carrier and used a seperate > > > modulator tube hooked up sort of in parallel to the final amp and > > > usually was the same tube type. There was no modulation transformer > > > like in typical class B High level modulation schemes. > > <snip> > > > > Hi, Mike > > > > You are thinking of "Rothman Modulation" April 1952 CQ. > > (Which I can't find). If I recall correctly, controlled > > carrier screen voltage for the finals was derived from the rf output > > carrier power. I remember a picture of an outboard box with a couple > > of 6Y6 style tubes (perhaps it was a single 6Y6 and a rectifier tube), > > modulating a pair of 813's. > > > > 73, > > Ed Knobloch > > --------------------------------------------------- > > > > and the reply was... > > > > --------------------------------------------------- > > > > Article: 101890 of rec.radio.amateur.boatanchors > > From: "COLIN LAMB" <[EMAIL PROTECTED]> > > References: <[EMAIL PROTECTED]> > > <[EMAIL PROTECTED]> > > Subject: Re: Info needed on "Taylor Modulation" from the 50's. > > Message-ID: <[EMAIL PROTECTED]> > > Date: Fri, 22 Oct 2004 18:05:19 GMT > > > > Hello Ed: > > > > My wife says I have so much crap I could not possibly find anything - but > I > > walked right to the shelf where the April 1952 CQ magazine was. > > > > You are therefore batting 1 for 3, since you got it right on the outboard > > chassis, but wrong on the 6Y6 style tube. However, when you get to be our > > age and have forgotten more circuits than the younger hams have ever read > > about, that is not that bad. > > > > Anyway, there were two different circuits shown. A 100 watt mobile > > modulator using a 6X4 rf rectifier with a 6SN7 modulator tube, and a fixed > > station modulator for up to 1000 watts uisng an 80 rf rectifier, a 6SL7 > > speech amp and a 6CD6 modulator tube. Since the 6CD6 tube has a plate > cap, > > it does not look like a 6Y6. The 6BQ6 and 6BG6 can also be used. > > > > I have a number of 6CD6 and 6BG6 tubes and never could figure out what to > do > > with them. This is the answer. Build dozens of Rothman modulators. > > > > I think later that year and into 1953, you could buy an "efficiency > > Modulator" using this system. They claimed 70% efficiency, which was much > > better than the 52% efficiency of high level plate modulation. > > > > And my wife thinks I cannot find things. Ha. > > > > 73, Colin K7FM > > ----------------------------------------------------------------- > > > > > > ______________________________________________________________ > > 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 >
