[AMPS] Additional Tube Brand Question

Tom Rauch W8JI@contesting.com
Thu, 1 Feb 2001 07:56:52 -0500

Hi Mike,

> Do you know what the resting Ep rating was for the stock L-4B? My L-7
> run around 2500V, and I am wondering how much higher I can run that
> before I start having to change tank components and the like. IOW,
> when you substituted the HB supply, how much if any did you raise the
> plate voltage?

You can not raise the HV too much before getting into trouble. 
Using a similar (same brand and model but with optimal contact 
arrangements) switch in failure tests, just under 3kV was the limit 
for normal mistuning (loading fully meshed on 20 meters, 100 watts 
drive). At about that dc *NO LOAD* voltage, the switch became 

At 2800 volts or higher, I'd consider adding an intentional spark gap 
across the input of the tank.

73, Tom W8JI

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