[time-nuts] Fine frequency adjustment in 5370B

[Brooke Clarke]

Hi David:

It's so easy to feed the PRS10 a 1 PPS from GPS so I don't understand 
your comment "I don't have anything locked to GPS yet, but even when I 
do, it is not always going to be that convenient for me"

Have Fun,

Brooke
-- 
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David Kirkby wrote:

> John Miles wrote:
> 
>> Correct, the only adjustment on the 5370B is on the 10811 itself. 
> 
> 
> Cheers. I thought that was the case, but confirmation is never a bad thing.
> 
>> The best
>> way to set it is to note the deviation after a long warmup with the 
>> counter
>> covers in place, then take everything apart and adjust the 10811 to 
>> remove
>> the same amount of deviation.  (If you set it to 10.000000000 MHz with 
>> the
>> covers off, it won't be there under typical operating conditions.)
> 
> 
> That's what I was intending doing, although the adjustment as far 
> courser than ideal on a counter with 11 digits.
> 
>> I don't bother keeping mine calibrated, since everything runs off GPS.
> 
> 
> I don't have anything locked to GPS yet, but even when I do, it is not 
> always going to be that convenient for me, so having a reasonably 
> accurate timebase in the counter will be useful. Sure, putting in a 
> rubidium locked to GPS would be nice, but not always practical for me.
> 
> Thanks very much John.
> 
> 
> 
>>
>> -- john KE5FX
>>
>>
>>> The frequency of the oscillator in my 5370B seems to be a little off -
>>> at least according to my Standford PRS10 rubidium. Although the latter
>>> has not been calibrated recently, I suspect the rubidium is more
>>> accurate than the 10811-60111 in the 5370B, so was intending changing
>>> the latter to that of the rubidium.
>>>
>>> Although when one removes the top cover of the 5370B, the 10811-60111
>>> can be seen with its adjustment control, I believe this is a course
>>> adjustment (18 turns is supposed to move it +/- 10Hz, at least on the
>>> 10811A).
>>>
>>> I know you can trim these oscillators with a fine control, using the EFC
>>> voltage. Is anyone aware of whether this is possible on the 5370B or 
>>> not?
>>>
>>> I have the service manual, and so no mention of it. Neither can I see
>>> any control, so I guess the answer is probably no. But the PCB the
>>> oscillator plugs into hidden beneath some shielding, so I am not 100%
>>> sure there is no pot.
>>>
>>
>>
>>
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>>
> 
>