My HP-103AR has drifted beyond the ability of the "coarse" and "fine" frequency adjustment capacitors. The 1 MHz output measures 0.999 9992 MHz and will not go higher. 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? Jeremy -- Sent from my iPad 4.

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

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 capacitance. I have the manual (got a copy from Artek) and read the oven temp procedure. Tedious but do-able. Jeremy On Thu, Sep 28, 2017 at 5:50 AM Charles Steinmetz <csteinmetz@yandex.com> wrote: > 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 > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Sent from my iPad 4.