[time-nuts] OXCO Issues -- Latest

Bob Camp lists at rtty.us
Sun May 12 14:37:32 EDT 2013


If the oven is cycling enough to swing the frequency > 1 ppm, doing a turn hunt is going to be pretty tough. You are looking for small fractions of a ppm as you tweak the trimmer. The other minor point is that you need to do it with the foam and cover on the oscillator. Drilling a hole in the can is not all that hard.


On May 12, 2013, at 1:59 PM, Ed Palmer <ed_palmer at sasktel.net> wrote:

> When you've got it powered up again, you should try adjusting the trimpot.  You should be able to find a spot that gives you a frequency minimum, assuming this is an AT crystal.  This will minimize sensitivity to temperature change.  There's a slim chance that a shift in the temperature set point could be at the core of your problem, but it would be a rather extreme case.
> Ed
> On 5/12/2013 9:36 AM, Frederick Bray wrote:
>> Well, I decided to make the "Y" incision and pulled the circuit board out of the oven.  (Photos later after I crop them.)
>> Yes, the trimpot is part of the circuit associated with the thermistor.
>> My plan is to check the resistors (surprisingly most are carbon film except those in the thermistor circuit), look at the circuit board under a magnifier, and stick it back in the foam for testing after making any repairs.
>> Thanks again for the continuing comments and advice.
>> Fred
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