[time-nuts] HP5370A self test fault characteristics anddiagnosis

Rex rexa at sonic.net
Fri Jun 19 05:32:46 EDT 2009

John Miles wrote:

>>On the 5370A part, I recently bought one cheap and it sort of works but
>>seems very noisey in its lower order digit readings; clean external ref
>>doesn't help. I haven't looked at obvious things like the power supply
>>yet, but I'm curious if the group has any thoughts of common problems to
>>look for.
>What mode are you observing the noise in?  Noisy LSDs on a 5370 are normal
>in many cases.
>-- john, KE5FX

I have a 5334B and looking at the same signal it seems more stable. From 
memory (I haven't tried it recently) the 5370 had 3 or 4 unstable low 
order digits. Even selecting high periods or sample size didn't seem to 
remove noise out of two or three digits. 

I never used a 5370 before, but this doesn't seem right. I get several 
random digits even looking at it's own clean 10 MHz external clock. That 
shouldn't be, should it?

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