[Amps] Newbie Question II

[W7RY]

Open (intermittent) grid resistors. Very common on SB-200s They are 33
Ohm. 

73
Jim W7RY




-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
On Behalf Of Bob Green
Sent: Thursday, September 28, 2006 10:15 PM
To: amps at contesting.com
Subject: [Amps] Newbie Question II

Hi again, everybody --

 

Thanks to all who answered. Now if I can just get my hands on the amp,
I'll
give them a try (The current owner just left town for 2 weeks).

 

Here is another problem for all the gurus out there. I also have a
SB-200
with most of the Harbach mods.(HVPS, Soft Start, Soft Key) It also has
AG6K's Parasitic suppressor.  Whenever I key it using my 756PRO in RTTY
mode, the output power is VERY LOW  (50-80 watts or so). Plate current
for
both tubes is running about 200-250 ma, and grid current pegs
negatively.
The tube plates turn a brilliant red-orange, and the heat above the tube
compartment goes WAY UP. Every now and then, the power out jumps to 700
or
so watts, but only for a second or two. The plates don't have time to
cool
off before the problem comes right back.

 

I have new Taylor 572B tubes (still in the box, in case I need them). 

 

What could be causing this problem? Would a shorted or open blocking cap
or
a tune or load control do this? I suspect the solution to this problem
is
easy, but so far it has eluded me. 

 

Only a week or so to the CA QSO Party. I'd sure like to use it then. . .
Any
ideas, anybody???

 

73,

 

Bob Green W6BBL

w6bbl at charter.net

 

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