Re: Max anode voltage?

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Original poster: Ed Phillips <evp@xxxxxxxxxxx>

I would like to believe I know what I am doing though I have not designed a
high power tube oscillator before.
I do not understand the fine detail on how the grid leak works or how to
handle the variable load presented by the tank and secondary under the
transient conditions of pulsed operation."

   Your problem is not only one of designing a high power oscillator 
but designing of one feeding a resonant and variable load.  Designing 
an oscillator for a resistive load isn't much different from 
designing a power amplifier for the same power level except that you 
have to figure out the feedback to get the required grid 
drive.  Knowing the operating grid bias and grid current (part of the 
amplifier design) you can then choose the self-bias resistor (grid 
leak).  The problem of course is getting the oscillator to start 
correctly so that the tube doesn't fry its little self due to lack of 
excitation with resultant grid drive.
When it comes to trying to drive a resonant load like a
TC, and particularly one where the load resistance and reactance both 
vary with output power and with time (streamer growth) things get a 
lot trickier.  I know a fellow who was designed in designing a power 
oscillator for a cyclotron which UCLA built some time back and they 
had a devil of a time getting the thing to work because of the many 
possible modes of oscillation it had and of the difficulty of getting 
it to start in the correct one.  I'm not sure they ever really 
succeeded.  Somewhere I have a reprint of a paper they wrote but 
don't know where it is.

Ed