According to my manual, it is HP Part Number 10811-80008, which is described as "UTG Fuse-Thermal 115C 1.0A 250V", in stock at HP for $5.69, available until gone. The old part number is 2110-0617.
I presume that means 115 degrees C. I purchased a few several months ago (price was lower as I recall) then found some elsewhere, perhaps Mouser, that were close but not exact. Joe -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Neville Michie Sent: Wednesday, September 15, 2010 7:32 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] HP 5370B - result The catch with the thermal fuse in an un-plated socket is that as it ages the socket oxidises and the heater current generates enough ohmic heating through a high resistance socket to heat the fuse through its leads. This opens the fuse the next time the oven is heated from cold. I just repaired a 10811 today with the same problem. Does anyone know the rated temperature for the fuse to drop out? cheers, Neville Michie On 15/09/2010, at 8:40 PM, Charles P. Steinmetz wrote: > After cooling and restarting the 5370B and observing its behavior, > we judged that it was more likely it had an unheated 10811 than an > oscillator of lower stability, so we popped the lid (the > possibility that it didn't have a 10811/10544 was the reason for > leaving it intact so it could be returned). Sure enough, we found > a cold 10811 and an open thermal fuse. After replacing the thermal > fuse with a jumper, all appears normal. (As others have noted, it > appears to me that if the heater control failed the crystal and > heater would suffer major trauma before the thermal fuse opened, so > we deemed it superfluous.) > > Thank you all for your comments and suggestions! > > Charles > > > > > > _______________________________________________ > 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. _______________________________________________ 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. _______________________________________________ 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.
