HP 3312A RF generator repair help

[Ron1973]

Hey Folks,
   Just acquired a 3321A function/sweep generator in really nice shape. I noticed the set frequency starts falling immediately after I set it. I have let it warm up for hours, and still the freq continues to fall lower and lower. I searched online for hours, and I can't find anything to lead me where to start. Any ideas would be appreciated.

[PA0PBZ]

Here is the service manual: http://literature.cdn.keysight.com/litweb/pdf/03312-90004.pdf?id=734381
Start by checking the power supply.

Can you give us an idea about the frequency falling, like what frequency you set it and how fast it is falling?
Since this is not a digital generator it will always be a bit unstable.

[Ron1973]

Thank you for the reply. I'm trying to align an old am shortwave radio. I set the freq at 455.00 kc. The freq pot is very jumpy. It  bounces up and down slightly at initial set, then just starts slowly dropping. It goes to 454.75 within 10-15mins, and then just keeps going down slowly. Is this normal? Am I asking too much from this aged machine. It looks very clean inside, and nothing looks like it was tampered with.
The service manuals online are pretty rough, and barely legible on the fine print schematics. Anyone have a clean copy of the power supply portion of the schematic?
Thanks

[PA0PBZ]

Considering the drift I think this is about what you can expect from a unit like this, 250 Hz drift in 10-15 minutes is quite nice.
I can't even find the drift mentioned in the specifications, there must be a reason for that...
If the frequency pot is very jumpy you could try to clean it with some contact cleaner, but overall there's not much else you can do.

Note: 454.75 KHz is well within the IF bandwidth of the radio (I don't expect it to have a 100 Hz CW filter), so don't worry, just make your alignment in 10 minutes