[time-nuts] Restoration of a 5065A - Continued

Ulf Kylenfall ulf_r_k at yahoo.com
Tue Sep 12 05:19:16 EDT 2017


Yes I noticed some peculiar behavior when I operated the A7stand alone on my lab bench, and tested the 2nd harmonic detector at 137and 274 Hz. Then when I examined the schematic for thenewer version I could see that HP obviously discovered the same thing.
I think I will make a home-brew board first. Time to dig outmy old etching stuff...

Corby Dawson wrote:

You either should replace the -6010 old style A7 or if building one from
scratch build the late style.
The new style has a BP filter on the 2nd harmonic that makes the 2nd
harmonic reading a better indication.
On the old style as you adjust the CF (in open loop) you will see the 2nd
harmonic reading rise! This is bogus and caused by the 137 Hz signal
bleeding through. On the new style when you move off frequency the 2nd
harmonic reading drops as it should!



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