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Re: Tube tester rating ambiguity

Mr. Haedt,
Most of your reply was good with an exception. "all the old testers in use today are NOT properly calibrated. So--this adds to the problem."
Negative! The procedures do take a long time to check everything properly.
Proper calibration procedures are out there: TV7 series Field and Depot Maintenance Manual are located in Army TM-11-6625-274-35 (Changes 1-5) 30 June 60.
Hickok 539C calibration procedures were in their factory manuals and they are easy to come by also, as are the B&K tester cal procedures (direct from B&K). Using a reference tube, the 539C can be cal'd to read the same transconductance as a TV7-D/U, given the initial calibration readings are good - very small tweak. I did it myself last week.
All this being said, does it mean that all testers out there ARE calibrated? Hell no! I would assume that most are not. It's easy to see some of the ads on E-bay and tell by the readings given that their testers are WAY off. So, I'll agree that this causes confusion. To the tube buyer - I suggest you ask the seller to show you his calibration results.
Testers are like amps, even the same model, are individuals and most likely will not give the exact same readings: too many variables, even with a good calibration. It's all relative, not absolute.
V/r
J


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