[TMC] Jumpy TMC vfo question.

[Ira Curtis]

Is the current regulator a "real " one? or are you using an old tube 's 
filament as replacement. Had same problem, caused by faulty filament current 
regulator.
Ira CE3AM.
----- Original Message ----- 
From: <jaredw1atr at sbcglobal.net>
To: <tmc at mailman.qth.net>
Sent: Saturday, January 13, 2007 1:01 AM
Subject: [TMC] Jumpy TMC vfo question.


Hello all. First post here, so greetings to everyone. I have a GPT-750 
question. On
my transmitter, the VFO jumps around slightly, (a few KC) when I key the 
thing up. While
transmitting, it will also move slightly with a light rap to the cabinet in 
the area of the
VFO, (or should I be saying 'MO').. It doesn't continue to go too far off 
freq, it will
jump up/down a few KC, then come back again on the next key,(or smack). The 
MO
frequency setting on the front is no where even close to the actual MO 
output freq.

Now I checked all the wiring, and the tubes in the back test fine, and are 
tight in
they're sockets. I did a voltage pinout on the wiring blocks on the left 
side of the MO box, and
all the voltages are correct. Before I take this thing out and strip it, I 
wanted to ask for any opinions or suggestions. Or even go as far as to see 
if anyone had a print for this circuit. (Nothing is avail on the net.)

For what it's worth, the rig is a 'C' model,(xfk box was installed in mid 
drawer), and
otherwise completely stock and unhacked when I picked it up in Buffalo a 
year ago.
Now, it has 4-400's in the final, modulated by a pair of 833's, in B, 
modified heis., with
Moloney iron out of a BC1T.(seperate bud cabinet for the modulator)

If anyone can offer suggestions on the MO problem or perhaps a
print, that would be great.

Thanks, Jared W1ATR
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