[AMRadio] Old Novice Days

Donald Chester k4kyv at hotmail.com
Sun Feb 27 13:23:58 EST 2005

>Anybody know where I could find a schematic for these amplifiers?
>Whats the best way to build a 1kw (capable) modulation transformer to plate 
>modulate an amp like these? Not that I'd want to. Just asking...

You would want to rewire the amp from grounded grid to grid driven, and 
convert the class of operation from class AB or B to class C.

Despite the high power ratings of these amps, the plate tuning capacitor is 
probably not rated for high enough peak voltage to accomodate positive 
modulation peaks, and the tank coil may not be able to take the 100% carrier 
duty cycle of plate modulated AM.

You would be much better off acquiring components rated for the service you 
plan to use them for,  and homebrewing your own modulator and class-C final.

I would recommend looking for a 250, 500 or 1000 watt plate modulated tube 
type AM broadcast transmitter (broadcast stations are discarding them every 
day as they convert to solid state to save on tube and power bills), and 
either converting it to cover the ham bands you plan to operate, or parting 
it out to build the homebrew plate modulated rig of your dreams.


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