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




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