[Heathkit] SB-200 shutdown

[David Cook]

I was operating my SB-200 (with all the Harbach mods) last night on 20
meters SSB when the unit just suddenly popped the breakers and shutdown in
the middle of a transmission. I'd been using it for about an hour when this
happened. I opened up the top cover to see that the breakers had popped and
found that the transformer was really toasty hot, as well as lots of heat
coming out of the tube compartment.

After letting the thing cool off for a couple of hours, and resetting the
breakers, I tried turning it on again and it came on just fine. I took it
out of the case this morning and measured the plate and grid resistances to
ground, as specified in the manual, and they seemed normal. I haven't yet
tried applying RF to it and figured I'd better get some opinions before I
attempt to put it back in service.

I inherited this amp about a year ago, put in the Harbach mods myself, and
have had no problems until now. I don't know how long it's been since the
tube have been replaced, but the thing has been putting out plenty of power
so far.

I'd appreciate any suggestions on what might have happened, and whether it's
safe to try running it again. Also, are there any other mods that I might
need to make (replacing old resistors, capacitors, etc.)?

Thanks for any help and 73 to all,
-- Dave, WA0TTN