SB 200 Power Output

[Ed Richards]

John;

You do not have a tube problem, you have a power supply problem. Your HV
is not stiff enough. Look for where the first voltage drop occurs. Start
with the line voltage and move to the power transformer primary to the
secondary, across each capacitor to the plate RF choke. Some where along
the line you will find a big change when you key- down. You should be
getting more like 600-800 watts. If you were only getting 400 watts it
was NOT in good condition.

Ed Richards

On Mon, 12 Feb 2001 14:16:20 EST John Barkow <KD6PT at AOL.COM> writes:
> High Gang: Several months ago I purchased an SB 200 amp in pretty
> good
> condition. Power output was about 400 watts DC on all bands,
> including WARC
> bands which wasn'nt too bad.  I have installed a Harback power
> supply board
> and "soft key" and it works great with my Kenwood 570..Lately the
> power seems
> to be dropping off and is now down to about 300 Watts.  The HV
> decreases from
> 2300V to around 600 volts when the amp is keyed but plate current
> stays
> constant.  I feel that the tubes are probably the problem but I
> could be
> wrong.  Let me know if any of you have comments on this before I
> invest in a
> new set of tubes.
> Thanks, John kd6pt
>
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