My spare TC tube, I got at a surplus store. Had the same question as to pinouts. Measured and found 4 pins, with same resistance between any two pins. Question was which pair were to the heater and which were to the TC.
Short of finding the pinout for your gage tube, the only way I could think of was to measure the voltage between the various pins till I found a real thermal voltage... (few tens of microvolts).
Some of the heater circuits are little more than a 120vac to 6 vac or something similar, and a microammeter connected directly to the TC in the gage.
I actually made a Pirani type gage out of a new flashlight bulb, from which I removed the glass and epoxied the base and filament into a copper tube. It gave nice readings with just a VOM reading resistance (low range actually heated the filament enough to work). Typically a filament resistance change of about 3 or 4 times could be gotten with a little drive current. So an entire measuring instrument could be built around a 7805 regulator set up to provide constant currrent of a few mA. The "absolute pressure" reading then is taken as a pressure dependent voltage measured across the bulb.
Dave Cooper
Created on Thursday, April 19, 2001 3:16 AM EDT by David Cooper