As you might expect, this problem turned out to be trivial once found.
The problem was that the black B- wire running from the cap board to the
diode/mixer board was hanging by a thread. Heath used stranded wire for this;
if I were building from scratch, I'd probably use solid.
It *looked* like it was attached, and when I did the meter testing the other
day I must have contacted the wire instead of the joint. But I went to examine
the joint closer, the one or two strands that were holding it broke off with no
effort. A quick re-stripping and re-solder and...
I'm now getting 3100V+ on the built-in HV meter. All good. Now I just need to
reassemble everything, close the case, and see if I can make the RF come out
and the smoke stay in. :-)
Thanks for the help and encouragement. The moral of the story is, when you
hear hoofbeats, think horses, not zebras. Usually it's something silly like a
bad joint or a bum resistor. For a while, I forgot that key bit of advice.
Amps mailing list