Hi Charles, Yes, the rear heatsink does run very hot, approx. 61 deg C. But do make sure the fan is running! The unit will be damaged without the fan. Also it's important to refrain from running the instrument too long with its top cover removed, because the fan air doesn't properly loop around and blow back out the heatsink if you've left the instrument top cover off.
As Bruce suggests, you'll want to peek inside to see that you really do have a 10811 oscillator. If so, then it sounds like the thermal fuse (F1, inside the 10811) might be open. According to the manual, I think the HP part number for F1 was 2110-0617. However, Agilent's current online parts search does not find that p/n. Maybe you'll have to call Agilent's "Parts ID" to identify the current part number for F1? ...Or probably others in this forum will offer more current information regarding what part to use for F1. Greg _______________________________________________ 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.