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 -----------------------------------------------------------------
