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Another fairly frequent problem with some of those was the H oscillator failing to start or being hard starting. Since the plate is supplied form B Boost, sometimes there isn't enuff juice on the plate for the osc. to start.
A quickie fix is to connect a diode (an ordinary rectifier diode) as shown, from the Boost line to B+. That way, the osc starts on B+, and then when the Boost comes up, the diode becomes reverse-biased and the osc runs on Boost as designed.
Since the design used low (135V) B+, the H output stage doesn't get hot enough to red-plate when there's no grid drive.
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09-23-2015, 10:41 PM
Linear Mode
