excellent repair and pictures On Fri, Oct 21, 2011 at 5:47 AM, Achim Vollhardt <[email protected]>wrote:
> Fellow time-nuts, > > my humble HP10811 + Shera controller combo signaled loss of lock since > about a week after 5 years of non-stop operation. Frequency measurement > showed it to be ca. 90 Hz low and the added oscillator enclosure (8mm > aluminum case) barely exceeded room temperature. Measurement showed oven > current to be zero and after some Google research, the thermal fuse for the > oven controller became the prime suspect. > > Opening the oscillator is rather easy due to screws, pulling the inner > isolation lid as well. With help of the service manual, the fuse is quickly > identified and proved indeed to be open. > > I had a 24V, 1.5A polyfuse at hand which was soldered in parallel to the > existing fuse. 1.5A seems a bit large, however I think some derating is > advantageous due to the elevated temperatures. Closed everything and first > connected the oven supply only: > initial 510mA, going down to 105mA after 10-ish minutes. Perfect. > > Putting everything together again and the HP10811 is again within 0.1 Hz of > 10 MHz without the control loop closed. Getting it back to its antenna later > the day.. > > For some hi-res pictures of the procedure: > > http://gulp.physik.uzh.ch/**HP10811_oven-repair/<http://gulp.physik.uzh.ch/HP10811_oven-repair/> > > Hope this is of help to anybody with the same problem. > > Regards, > Achim > > ______________________________**_________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/** > mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
