[TMC] Jumpy VFO

[jaredw1atr at sbcglobal.net]

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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