[time-nuts] Re: Efratom M-100 102 not locking

[Peter Gottlieb]

The frequency wanders up and down around the correct 10 MHz but never locks. 

The next step seems to pull the tube and let it heat up and see if the Rb changes. 

Peter

> On Nov 27, 2025, at 5:10 PM, Wilko Bulte via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> hello Peter,
> 
> Obviously it "all depends" on the actual failure.
> 
> But I did succesfully repair an Efratom FRK-L Rb unit that failed to lock. In my case the temperature of the crystal oven was far too high which in turn made the XO frequency go way out which made it impossible to get an atomic lock. Turned out the oven control opamp along with its drifted feedback resistor caused it. So, cheap fix in the end.
> 
> I would suggest to measure the frequency it produces first, to get an idea if it is close enough for a Rb lock to be feasible.
> 
> Wilko
> 
>> On 27 Nov 2025, at 21:13, Peter Gottlieb via time-nuts <time-nuts at lists.febo.com> wrote:
>> 
>> I have this Rb oscillator which has output but won't lock.
>> 
>> Are these repairable?  Worth the effort?  Date code is from 1989 so it may have a lot of hours on it.
>> 
>> Peter
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