[time-nuts] HP5065A revival

Magnus Danielson magnus at rubidium.dyndns.org
Sun Sep 18 13:26:41 UTC 2011


Dear fellow time-nuts,

I now have a HP5065A on the bench. It seems to behave pretty decent, but 
it does not lock up completely. It does lock up, but the lock light does 
not light up. When checking the signals into the logic board (why didn't 
they provide a fault diagnosis? Even the russians could do that!) it 
seems like the A1 synthesis does not feel happy. I found several small 
issues, one being the unsoldered wire, another was an SMC connector not 
properly tightend, probably after service attempts. The thumbwheels 
where way of, but putting them into good known locations I was able to 
confirm lock and use the C-field tuning to bring it into close proximity 
to UTC (as given by the 10 MHz comming out of my Thunderbolt).

I get something like ADEV(1s)= 5E-11 when comparing it against my 10 MHz 
using the TS-105A in double-mixer setup. The TS-105A isn't the ultimate 
tool by any sense of the word, but it is nice to be able to use it as 
part of an early diagnosis since it is very "direct".

The other HP5065A is a bit more of a challenge, so I will have to work 
more on the PSU side of it first.

Anyway, I would apprechiate some experience with fault diagnostic and 
trim-up on HP5065A so I can get these back into spec. It always takes a 
bit longer when new to them. All the signal checks look healthy now, so 
it is only this minor issue.

Oh, don't bother tossing me links to manuals, I have two original 
manuals at hand. I need some hands-on experience to assist me.

I will also try to do the same to my CH1-78 rubidium. It is interesting 
to note that the "large" HP5065A physical package is about half the size 
of the CH1-78 physical package. The CH1-78 also needs trimming.

Cheers,
Magnus




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