[time-nuts] HP 5065A Start-Up

[John Miles]

> Microphonics.
> 
> What's the norm here?  I see it in the 2nd harmonic level on the panel
> meter.  It runs about 20 normally, but a pretty light tap (with my
> fingernail) anywhere on the instrument can peg the meter for a few
> seconds.  While I had the scope on A8 TP2 / TP3 (showing the off-resonance
> phase shift peak it manifested as bursts of noise) It's hard to localize -
> but I think the RVFR and Synthesizer are the most sensitive.

If your 5065A is like most of the older ones I've seen, it has been upgraded with a 10811-60109 OCXO.  If so, there is a spring-loaded shaft extension that allows you to access the 10811's calibration trimmer from the panel behind the hinged door.  It can be a good idea to remove that hardware, since it can otherwise transfer external vibrations to the OCXO.  That probably isn't enough to pin the meter but it's still worth checking.

(Be sure to check the ESR of all of the axial tantalum electrolytics on the RVFR oven control board, if you haven't already.  A failed oven controller can really hose the RVFR.)

-- john, KE5FX
Miles Design LLC