Thanks for the info Ed, I have learned a lot and you and everyone else has
been a great help. I removed the blown resistor and reconnected the lead and
the amp works FB again, so problem solved. Im glad it turned out to be so
simple. I will install another 10ohm 10W resistor to replace the blown one
in the near future before I put the amp back on the air for real.

Thanks again all and 73
Chris
VE9CEH

"Edward Knobloch" wrote in message
...
On 4/11/2011 3:37 PM, Christopher Hall wrote:
Thanks to all who have posted regarding this issue, its been a lot of
help.
I checked the HV to plate circuit and found a blown (actually totally
destroyed) wire wound resistor in series between the filter board and the
plate choke. The manual and schematic doesnt show this resistor as part
of
the kit, so Im assuming it was a mod done by the original owner. I
suspect
it may be there to lower the voltage on the plate to extend tube life or
to
provide some safety a la Eds post regarding a RF choke to provide some
sort
of fuse. The problem is the resistor is so damaged that there are no
values
printed on it. Does anyone have any ideas as to what that resistors
values
would be?


Hi, Chris

That resistor in series with the plate lead is a good, standard mod.
The usual value is 10 Ohms, 10 Watts, enamel coated wirewound.

Here's a picture of one added to a Kenwood TL-922 amplifier:
http://ve3fwa.ham-radio-op.net/tl922/mod7-an.htm

(The guy used a 12 Watter there, no problem, that's a bigger amp).

The idea is that should a 3-500Z arc over, the resistor will open
(and +stay+ open). Hopefully, this will happen fast enough
to save the tube and the plate rf choke.

73,
Ed Knobloch