? And what was the low freq. limit for the HP 431 thermistor mount? As I recall, it was c. 10MHz. It depends on the model. Below 10 MHz you might as well use a stopwatch. -- FAQ on WWW: http://www.contesting.com/ampsfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: http://www.contesting.com/km9p/search.htm