In case anyone is interested in the saga of my SB-1000, I did the following
today:
1) Replaced the plate choke with the Ameritron AL-80B choke. Whoever suggested
that
resonances must be checked with the choke installed was correct; with the choke
in
its place and wired up, the primary series resonance appeared at a reasonable
16 mHz;
no other noticeable resonances were found.
2) While I was at it, replaced the #14 tinned leads from the 10/15/20 meter
taps of
the coil to the bandswitch with 1/4" copper strap.
Results: nada. I still am getting only about 500 watts out on 15 meters
(previously
I said 600; that was an error). I've got plenty of drive capability; but the
amp is
loaded to 400 ma plate current with about 160 ma grid current, and increasing
the
drive does not produce more output. The plate voltage is about 2850. About 850
watts is easily obtainable on 40, and about 730 on 20.
Someone suggested that the 3-500z might be marginal, and that this would show
up
first on the higher bands. Any comments?
Vic K2VCO
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