Hi Tom -- The thermistors in the 732A are all nominal 10k ohms at 25 deg C. The monitor thermistor has no function in any control loop -- it is only there for a quick check of correct oven operation. It is fully floating, with no electrical connection to any other part of the unit. The nominal oven temps of the two 732s I used to have were in the 46 deg C area, plus or minus 1 deg. Although the Fluke thermistors are very tiny units, any glass-housed or epoxy-bead nominal 10k thermistor will serve well for the monitor function, and even for the control loop thermistors, as long as they physically fit. But physical access to the various thermistors is no walk in the park.... Dick Moore On Jun 29, 2012, at 4:33 AM, volt-nuts-request@febo.com wrote: > Message: 1 > Date: Thu, 28 Jun 2012 19:04:06 -0400 (EDT) > From: Leedyt@aol.com > To: volt-nuts@febo.com > Subject: [volt-nuts] Thermistor value for 732A Reference 10V Standard > Message-ID: <311ac.2492ac57.3d1e3ce6@aol.com> > Content-Type: text/plain; charset="US-ASCII" > > > > Hi! > > Can anyone give me a rough value of the thermistor resistance that is > brought out to the front panel of a Fluke 732A DC Reference Standard (lower > left-hand side)? The thermistor is for the user to monitor the temperature of > the oven that contains the voltage reference. I see a resistance that > starts out at 6600 Ohms (unit was nearly cold) and climbs and levels out at > about 8400 Ohms after a day, or so. Is this reasonable? The thermistor is > given in the parts list as RT2, a Fenwal JA41J1 (no longer made) and on the > schematic as a 10K @ 25C unit. So this doesn't make sense. > > Does anyone have any experience with this? Or is just simpler to replace > the thermistor with a 100 Ohm RTD and be done with it? Or would this drive > the calibration labs nuts? > > Any references or advice would be appreciated. > > Tom Leedy > Clarksburg, MD > > ------------------------------