[Amps] Soft 8877???

Steve Thompson g8gsq at qsl.net
Tue Oct 7 12:19:36 EDT 2003


On Tuesday 07 October 2003 01:55, Paul Ash wrote:
> Hello All,
>
> A quick newbie question.
> I recently picked up an old Henry 3K X
> that had sat unused for the last 17 years.
> This is the version with the 8877.
> This is my first 8877 based amp and I'm seeing
> some odd behavior:
>
> Max power out 700W. (from what I understand
> I should be getting 3X that.)
> Virtually no grid current.
> Plate voltage looks ok, 4000V in SSB 3000V in CW mode. However, the output
> does not change from one plate voltage to another. Just seems to hover
> around 500-700W. I have tried driving it to 900mA on the plate
> and 400mA on the plate, observed some difference but
> not much, maybe 25% difference.
>
> Any ideas? At first I thought it might be the tuning circuits but I'm not
> sure. Or, is it the tube? Seems to me that if I can pull 900mA through the
> plate then the tube may not be bad...
Could it be that the loading is much too heavy, so the plate sees too low a 
resistance?

Steve


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