[Amps] CW and High Voltage

[Steve Thompson]

Steven Cook wrote:

>Team,
>
>I've acquired an older Henry 2K-4, which only has one High Voltage setting ~ 3500V no load.
>
>It runs a pair of 3-500z triodes and will be driven with ~100W
>
>My question concerns running the amp at reduced output on CW and if it is better to:
>
>1.  Apply full drive, and adjust C1 and C2 until the desired level of output is achieved...
>
>or as some have suggested:
>
>2.  Apply full drive, adjust C1 and C2 until maximum power is achieved, then reduce the exciter drive without readjusting C1 or C2.
>
>What is the ramification of starting out with reduced drive, (like 25 or 50 Watts) and adjusting C1 and C2 until maximum output is achieved?
>  
>
Very simplistically, 1 (correctly adjusted) gives you highest efficiency 
at the expense of gain and linearity. I think 3-500s were designed for 
class C and continuous operation, so there should be no worries about 
tube stress. Harmonics might be higher, but whether you will see a 
signiicant difference in what's radiated will vary according to 
filtering/atu/antenna.

2 gives you best linearity at the expense of efficiency - your keying 
waveform will be least affected.

Tuning for max output at reduced drive gives you highest gain, so you 
can run your exciter at lowest level for any given final output.

Nothing I can think of that's fundamentally wrong with any of them.

Steve