HP 8657A off freq

[steele]

HP 8657A off freq, just purchased of of flebay was supposed to be calibrated

To show 27.20500 on the spectrum analyzer peak center marker,  I have to have the 8657A set to 27.20491
I have not found the internal adjustment on the 8657A to set the frequency properly on the 2 so called service manuals I downloaded.
Any info would be appreciated
(the equipment was also running for over 9 hours)
Thanks

[Grandchuck]

I suggest a frequency counter to be sure.

[bob91343]

I have an 8657B with the high stability option.  The frequency calibration is accessible via two holes in the add-on module on top, the one at the rear of the generator.

Read the manual.  It's in there.

If you don't have the high stability oven, I can't help directly.  In any case, there is a warmup time necessary before full stability is achieved.  For mine, it's about 45 minutes, since while the oven is always plugged in, the oscillator isn't and so there is some drift.

[bdunham7]

To show 27.20500 on the spectrum analyzer peak center marker,  I have to have the 8657A set to 27.20491
I have not found the internal adjustment on the 8657A to set the frequency properly on the 2 so called service manuals I downloaded.

Does it have Option 001?

[steele]

This is what I have now after letting it run all day

[Ray Gianelli]

It's not in the service manual, but you will find it in the Operation and Calibration manual, PDF page 229.  Time base adjustment is A3R22.