Temperature probe for Tek 7D13?

Most of the temp probes of that vintage were merely a transistor at the end of a wire. Tiny ceramic Pill packages stuck on the end of a stick. If the 7D13 uses the difference voltage at two current levels, most any transistor will work. mike

Thanks for the info; i really appreciate it. The Tek 7D13 uses a special 4-pin connector; two are closer to the entry than the other two, insulation making a "D" shape. It would be hell to find a matching connector. Then there is the case of what the "extra" two are for... ...and how wired.

Robert Baer wrote in news: snipped-for-privacy@earthlink.net:

A "Lemo" connector. Digi-Key sells them,IIRC.

One's used as a shield connection,IIRC. IIRC,the same temp probe was used for the DM501(non-A).

Someone was kind enough to e-mail me a link to a DM501 schematic. With that, i found two corroded tantalums (corroded weld at case on negative lead); replaced them with aluminum electrolytics, and it works fine. 2 wires are for emitter and collector; shield (ground) is the base of the NPN. The other 2 in this case are for measuring voltage.

I appreciate the help from everyone. Thanks!!

The connector is called a LIMO connector. Not sure whether that's the name of the manufacturer or what.

You really should get the correct info for the 7D15. TEK used two methods. One just based the reading on the voltage of the remote junction. A more accurate method measures the voltage at two different currents and does some math to get the temperature. I think it matters how the transistor is wired...but maybe not. I think the transistor is much more critical for the one-current method. If it's got a junction, the two-current method will work. Can't hurt to try it. mike

Thanks; Limo is the name of the manufacturer of many spiffy and compact connectors that make the old MIL styles look like elephants by comparison. Got on their website and found the mating connector. I was not aware that Tektronics used two methods - had the impression they used the two current method, as that needs almost zero calibration and allows probe interchangeability. The "math" is in the form of simple differences, and ordinary op amps, resistors, etc are used. The schematic of the DM501 was very useful, and (except for part numbering like Q123) essentially identical to the 7D13. I found the other pair of wires is for remote voltage measurements.