[time-nuts] Frequency Counter Errors

Jerry Mulchin jmulchin at cox.net
Thu Mar 22 03:01:35 UTC 2012


Thanks to all that replied.

The problem is my 5328A reference input amplitude, and possibly the input module.
I lowered the reference amplitude to 4.9v p-p and the accuracy got better, but not
the same as the 5372A. So I suspect that the input front end may have something
wrong with it. I have a spare 041 module so I will replace the current one at a later date.

I did confirm that the 5372A is good by comparing the reference frequency as an input
signal to the counter. It is dead on at 10.000000000MHz, and I also confirmed it against
my 5370B counter as well. The same thing there. So my 5328A is suspect.

Thanks again.
Jerry


At 05:05 PM 3/21/2012, you wrote:
>I have a question for the collective group.
>
>I have a HP 5372A and a HP 5328A frequency counters. Both counters use the same
>PRS-10 Rubidium frequency standard driving a 6 channel reference distribution amplifier
>to each counters reference input port. The problem is this;
>
>When I measure the same frequency on both counters, (done one at a time) the frequency
>is generally off by about 300 Hz or so between the counters. Now I would expect an error 
>of +/- 1 digit, but 300Hz seems a bit strange to me. I can not find the problem and the 
>difference exists even if I use the internal timebases of each counter, give or take the timebase errors.
>The frequency is always at least >200 to 300Hz off between the two counters and I don't know
>which one to believe. You know the "man with 2 clocks" problem.
>
>Anyone have any idea what may be causing this?
>
>Thanks
>Jerry
>
>
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Jerry Mulchin





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