|[AMRadio] Re: WRL Globe King 500C rebuild|
k4kyv at hotmail.com
Fri Jul 7 02:27:16 EDT 2006
In the stock transmitter, the final amplifier plate voltage is 1800 volts,
so the 2000 volts shouldn't cause too much of a problem. The modulator
originally ran only 1200 volts on the plates of a pair of 811A's, and the
modulation transformer was just barely step-down, with a turns ratio of
something like 1.15:1. Even so, the modulator would just barely make about
85% modulation in most transmitters, if you were lucky.
Running 2 kv on both with a common power supply should give better
modulation, but the final tank cap might arc over on modulation peaks. This
is assuming that the G-C driver stage is capable of fully driving the
modulator at the increased plate voltage. With a common power supply, the
modulation transformer should have turns ratio of about 1.4 or 1.5 to 1.
The 572B's MIGHT work OK with the stock audio driver and mod transformer.
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