[AMPS] TL-922 at 4000 V

[Tom Rauch (W8JI)]

QROKING@aol.com wrote:
> 
> Ok fellas, lets let Heath, Ameritron and kenwood off the hook for a moment
> and lets look at the Drake L4-B.  My guess is that this unit can easily
> handle 4000 volts on the plate instead of there mere 2600 that is stock.

The TL-922 was designed under the old 1 kW dc input guidelines. It's
pretty easy
to get a 3-500Z amp to hold up and behave at voltages less than 3 kV.

Raise the voltage much over 3500 volts, and you are in for some real
problems.

Everything from the cooling system to the tank circuit
will need to be looked at. The tank heating will be much worse than the
power increase alone might make you think, because with that voltage the
loaded Q
will be higher (unless you change tank components). 

People already damage bandswitches and tuning caps with stock anode
voltages. You'll be adding about 1/3 more tank voltage *if* you tune the
PA correctly, and well over two times the heat, to get just about 4 dB
more signal on CW.

Mis-load the PA or loose the load through an antenna
system failure and you can bet the bandswitch or tuning cap will be
history.

I'm not convinced 4 kV on a PA designed for less than 3000 is a good
idea. 

73 Tom


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