[AMRadio] AM Transmitter Advice??


Mike Sawyer w3slk at uplink.net
Wed Feb 15 18:48:52 EST 2006


Don, K4KYV said: Sometime in the late 1920's, it occurred to someone that 
class-B linear
amplification would work just as well for audio as for rf, and the class-B
audio amplifier was developed.  The unusual thing about this setup was the
large audio transformer required.  Many rf linears were single-ended, and
depended on the fiywheel effect of the rf tank circuit to supply the missing
half of the sinewave output.  With class-B audio amplification, the tubes
have to be in pushpull in order to reproduce both halves of the sinewave.
Thus the well-known "class B modulator" came into being.

Interesting that you mention this Don. I just read where it was Art Collins 
and his group that came up with the idea of using Class B push-pull audio 
for Class C rf amplifier. I'm not a Collins aficionado but Joe, N3IBX gave 
me the book, "The First Fifty Years of Collins" to read and I found it very 
good reading. There was some self-promoting in there but I was mildly 
surprised when I learned Collins did discover the Class B P-P plate 
modulation scheme.
Mod-U-Lator,
Mike(y)
W3SLK




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