Folks,
I have had a Dentron 10-160L for a bit over a year now. It needed a new set of
572Bs and I added grid current metering in the cathode ground return. I was
using it during the ARRL DX contest in February with good success (1200W) for
nearly 14 hours on 160m through 15m. After an hour into running 10m the
transformer overheated and released it's smoke. The cooling fan I had over it
really added to the show.
Anyway I replaced the transformer with a Peter Dahl and now rather than the
2400V resting plate voltage I get 3000V. The problem I am seeing is that with
even 7V of negative grid bias I get a no signal grid current of about 160mA
and plate current of about 200mA. With the original transformer the grid
current was near zero.
While I am reasonable with amplifier basics and have muddled my way through
working on a few, I don't have troubleshooting experience of this collective
group. Have I given enough information to get any advice? I am a bit baffled.
My next step was to borrow a 220V variac to get to a lower B+ (if I can find a
local with one!!) any help? Questions?
Thanks!
- --
73 es God Bless de KK1L...ron (kk1l@arrl.net) <><
QTH: Jericho, Vermont
My page: http://www.qsl.net/kk1l
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