[time-nuts] HP5370A self test fault characteristics and diagnosis

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jun 19 06:46:15 EDT 2009

Rex wrote:
> Bruce Griffiths wrote:
>> What is the indicated std deviation of the delay between the STAR and
>> STOP inputs when connecting the rear panel 10MHz signal to both START
>> and STOP inputs using the STAR COM position of the channel mode switch?
> Bruce,
> I don't think I understand exactly how to measure this.
> First, let me say that this is a very early 5370A. It doesn't even
> have a 10544, it has the early crappy reference. Hence, I have been
> feeding it a better signal to the external ref input.
> Now, I am assuming you are talking about measuring a version of this
> reference signal. I think you are saying, put the front panel switch
> to START COMMON. Are you saying to feed in phase inputs to both Start
> and Stop inputs? I thought Start Common tied them together. Then I
> have no clue how to gather a reading for std deviation.

Yes, I should have given clearer instructions, just connect the 10MHz
out to  the START input with the swich selecting both inputs as COMMON.
Even with the ECL gate based crystal oscillator (my 5370A has one as
well even though its not a very early one, HP seemed to jump back and
forth between having a cheap oscillator and having a 10544A as standard)
the standard deviation should be less than 100ps. Typically something
like 15ps. With an external 10MHz signal connected to both inputs in
COMMON the STD deviation will be a little larger perhaps 35ps or so.

> Sorry if I am being dense. This counter, though very old, is new to me.
> Thanks for the help and suggestions.
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