[time-nuts] HP 5372A TIA Question

Poul-Henning Kamp phk at phk.freebsd.dk
Wed May 30 19:03:20 EDT 2018

In message <c10d6b2a-79c3-931d-1439-347fce06ff81 at rubidium.dyndns.org>, Magnus D
anielson writes:

>Consider that you need to swap the cables to verify that it is static
>with the setup and does not follow the cables. 

Run long series of measurements with the HP5372A OCXO free-running
and with it slaved to the DUT clock.

Any imperfection in the interpolator will show up as different noise
characteristics in the two results.

There is a test in the service manual which will give you a good
indication how well tuned the interpolator is, run that before
touching anything, and don't attempt to tune the interpolator
unless you can follow the procedure in the manual *exactly*.

PS: I do not recall it being mentioned, but the 1 MOhm input pods
are horribly unstable compared to the 50 Ohm input pods, which are
basically just a stripline and a BNC connector.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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