Tim Shoppa escribió: > For a while, didn't HP sell temperature probes which were in fact > quartz crystals? Oscillation frequency was converted by some simple > electronics to a temperature, and at the time (60's?) they were > exquisitely convenient for measuring way better than a tenth of a > degree. > > > Either the frequency drift was negligible or it > was so slow that I don't remember any manual removal of frequency > drift effects. > > At least one model is the 2804A. Not much info about it in the Agilent web site, but according to the 1986 catalog 'the temperature sensor is a quartz crystal whose precise angle of cut gives an stable and repeatable relationship between the resonant frequency and temperature'. But also is mentioned there that 'The only adjustment necessary to remove effects of thermal history on the sensor is a simple ice point or triple point calibration adjustment using the front panel thumbwheel switches'.
Since the ice-point calibration would only be able to remove an offset, I understand that this is the manual removal of frequency drift effects. Of course, I suppose that the dritft would be small compared with the quartz temperature coefficient. Anyway, a 10544 oscillator has a cold offset that can easily be of 1000Hz, so if at 80 deg. C the offset is zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough 15Hz/deg C average tempco in that range - and the aging drift for this oscillator is quite less than that. Best regards, Javier, EA1CRB _______________________________________________ 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.
