[time-nuts] Re: HP 5061A oscillator problem

[vilgotch1 at gmail.com]

H all,

I spoke too soon regarding the crystal oscillator in my 5061A. 
Disconnecting the fast warm-up heater only extended the time before it 
fails. There's obviously a temperature sensitive fault in there. I'll 
either have to try repairing it or find a replacement.

Morris


>Hi all,
>
>  Since 2006 my in-house frequency standard has been a HP 5061A which 
>still has a good physics package. I have retrofitted a Shera GPS system 
>to it in the disused battery compartment and run it occasionally on the 
>Cs to keep it nice.
>
>Recently I turned off all lab power while I was away for a few weeks 
>and when I turned it back on the 5061A wasn't working properly. It 
>would start up and run for a few minutes and then the outputs would 
>disappear. I have traced the problem to the 00105-6013 crystal 
>oscillator unit and I think what is happening is that the rapid warm up 
>thermostat is stuck on. When starting from cold it runs OK until the 
>innards get too hot and then it fails. When I disconnected the AC feed 
>to the rapid warm-up heater the oscillator runs properly and the osc 
>heater meter starts at the extreme right end of the scale before slowly 
>backing off over an hour or so and the oscillator unit feels warm.
>
>What I want to know is:
>
>1. Is this a reasonable explanation and has anyone seen such a fault 
>before?
>2. How long does the 00105-6013 take to get to operating temp using 
>it's internal controller  without the rapid warm-up?
>3. Is the crystal oscillator unit repairable? I suspect a replacement 
>thermostat would be unobtainable.
>4. Does anyone have a replacement 00105-06013 unit available? To my 
>eternal regret I had a spare and sold it a couple of years ago. It just 
>goes to show you should never throw anything out!
>
>Thanks for your help and 73 to all,
>
>Morris VK3DOC
>Melbourne, Australia
>
>
>