[time-nuts] HP-103AR frequency beyond adjustment

Jeremy Nichols jn6wfo at gmail.com
Fri Sep 29 19:29:07 EDT 2017

Thanks, Charles. I'll give it a try. Wanted to ask before attempting what
will be for me a new procedure.

I suppose I could also try replacing C117, the Fine Frequency Adjust
capacitor, to see if that has any effect. C117 is a 6.8-99 pf variable
geared to a shaft revolution counter. The counter is at maximum (600) but
the manual doesn't say if that is at the minimum or maximum end of the

I have the manual (got a copy from Artek) and read the oven temp procedure.
Tedious but do-able.


On Thu, Sep 28, 2017 at 5:50 AM Charles Steinmetz <csteinmetz at yandex.com>

> Jeremy wrote:
> > The only thing I've not adjusted is the oven temperature.
> > I know there's been discussion of this subject here in the
> > past but my searches come up empty—I must be using the wrong keywords.
> > The 103AR is just a toy for me so no harm is done if the frequency can't
> be
> > raised to 1 MHz but if it's possible I'd like to try. Have I missed
> something
> > somewhere?
> To adjust the frequency trim range, replace selected capacitor C103
> inside the oven (nominally 18pF).  Use a C0G/NP0 ceramic.  Note that HP
> indicates this "Component [is] not separately replaceable."  But at this
> point (nearly 60 years on), opening sealed oven assemblies has become
> routine for those who maintain old HP standards.
> The procedure for adjusting the oven temperature is described in
> paragraph 8-11 of the operating and service manual 01037-2 (printed Jan
> 1962).  Be advised it is somewhat tedious.
> If you do not have the manual, you can download it here:
> <
> http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/HP_103AR_quartz_oscillator_op_service_manual_1962.pdf
> >
> Best regards,
> Charles
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Sent from my iPad 4.

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