[AMRadio] Re: Home Brew

ne1s ne1s at neandertech.com
Wed Sep 29 13:02:45 EDT 2004

Cathode modulation works best with triode RF finals. With testrodes you end 
up with mostly grid modulation because of the (much) higher gain of the 
grid-cathode circuit. The 50's handbooks (Left Coast & ARRL) explain this. I 
presume high-mu trodes probably have the same issue. 

Last spring I experimented with a grid modulator (inserted in the cathode 
circuit) of a class C 807 PA. Worked well, but only about 7W of carrier out 
(about what you'd expect from an "efficiency-modulated" 807). 

 -Larry NE1S 

Crawfish writes: 

> I am trying to figure out how to cathode modulate the 4-1000 I have. I have
> a pair of 813's and have a 4-125. Have a bunch of 807's and 1625's as well. 
> Joe W4AAB

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