I've tracked down the arcing in my L7. It's from the plate choke to the HV
capacitor (circuit board) that is tapped from the hot side of the choke to
the center of it. For some reason it's arcing here, but only when
attempting to tune on 40 and 80. The amp tunes fine on 15 and 17 and 20. I
guess I'll replace the HV cap although I don't know if this will cure it.
Any other ideas as to root causes and why trouble only on 40 and 80? Could
it have something to do with the 3-500Z's?
Checking with a VOM both tubes cold show a short between pins 1 and 5 which
they should since my handbook shows 1 and 5 as the filament. However, on
one tube it shows "open" between grid pins 2 and 3 and 2 and 4 - - this
tube does show "short" between 3 and 4. The other tube shows "short"
between all grid pins (2 to 3, 3 to 4, 2 to 4) which I assume is correct
behavior. There is no short between any pins and the plate when checked
cold so that ain't the problem.
The band switch and tuning caps show no signs of problems.
Assuming I only need new tubes to get her running "good as new, " what is
the latest on best type/brand/dealer etc. for 3-500's? I read some of the
archives. Are there any new opinions?
73 and thanks a million,
Matt--K7BG (You're dad-gum right I'm an appliance operator, but I fix most
of my gear if I can)
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