I worked at a 'little' shortwave station in Greenbush, Maine that did that.
The tube anode was supplied by 28 modules @ 1 kV each. Solid state control
switched in the number of modules required via fiber optic control lines. I
think they used a method was called DCC (Dynamic Carrier Control). The
transmitter was made by BBC (Brown Boveri Company).
I did manage to get a little time during "maintenance" windows to use the
Sterba curtain for test purposes.....
At 12:18 PM 10-06-99 +0100, Peter Chadwick wrote:
>
>In the early 1970's there was a National Semiconductors app note on a
>modulated switching regulator, supposedly for use in powewring a high
>efficiency solid state HF linear. The idea was to vary the supply voltage in
>sympathy with the envelope of the modulation, so maintaining efficiency.
>
>Does anyone know of any work done on modulating the plate supply of a tube
>amp in sympathy with the envelope of the signal? When you consider that a
>pair of 6146's were rated for 100 watts carrier, 100% modulated, which is
>400 watts PEP in AM service, then some sort of plate voltage variation with
>modulation would appear to give the posssibility of 400 watts PEP of SSB.
>
>You might even get 1kW linear out of a pair of 4CX250Bs that way!
>
>And no, this is NOT a G2DAF.
>
>Could we see modulation transformers coming back into fashion?
>
>73
>
>Peter G3RZP
>
>
>
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>
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