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Title: Clamp It! G3HUL tells all! Post by: WA4WAX on May 07, 2016, 12:21:18 AM See page 46.
I know, someone rotated the pages. Uggh! http://www.americanradiohistory.com/Archive-Radio-Constructor/50s/RC-1955-08.pdf Title: Re: Clamp It! G3HUL tells all! Post by: Opcom on May 08, 2016, 10:20:08 PM Here's a helped version of just the article!
Title: Re: Clamp It! G3HUL tells all! Post by: WA4WAX on May 10, 2016, 08:17:57 AM Thanks for the clean up!
The idea of running feedback from modulator tube to driver is interesting. This approach would be good for a pair of 4D32's. I wonder if you could get the mod depth up to about 90 or 95% with low distortion. That would be fairly impressive. BTW, Mr. Mallett was still alive and active with RSGB as of 2009. Perhaps he is still around................... Title: Re: Clamp It! G3HUL tells all! Post by: DMOD on May 10, 2016, 10:41:44 AM This is also called a "shunt" modulator. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
The Ameco TX-86 used this same modulation method and sent some of the audio to the Final's grid bias circuit as well as to its screen. The shunt modulator is a power hog since the modulator tube has to operate in Class A with a high plate voltage. A better method is to use a cathode follower to modulate the screen voltage and send a small fraction of audio feedback to one of the speech amplifier stages. Phil - AC0OB |