GordonW said:To be fair, testers like the Sencore "Mighty-Mites" mentioned here, WILL also find shorted tubes. In fact, they're my GO-TO for quickly finding shorts (and we have a TV-7A/U as well!). The short test on the Sencores not only tells you there's a short- it can specify WHICH PINS are shorted, as a normal part of the test (ie, you don't have to jump through hoops or hurdles flipping a bunch of switches, like you do with other testers)! This can help in finding DIFFERENT VERSIONS of tubes or determining improperly-labeled substitutes- knowing which pins are wired together (intentional short, in essence) can be a BIG CLUE in finding out what a tube ACTUALLY IS, in the case of fakes and bad substitutes.
Also, you can also find out tubes that are "tired out" by doing a cathode-sensitivity test... the Mighty-Mite manual says to turn down the filament voltage one notch, and watch the emission for drop-offs. I've spotted MANY marginally bad tubes that way. For this, it's much faster than firing up the TV-7A/U, for garden-variety issues (as in "does this tube work at all or not?").
anatech said:Hi Gordon,
Problem is, some tubes normally show shorts between one set of elements. You need to know which ones. That and most testers use a heater voltage drop to check "life". My 9-66 does as well.
Seems to me that the fastest test is to try another tube, or measure the circuit voltages. If you were to leave your TV-7A/U out on the bench, it would be as easy to test using that. Both types require a bunch of settings and there is a "good/bad" or "English" scale on yours too.
I also have a B&K "Dynaquick 600" (something like that). I don't use it much because it misses too many bad tubes. I keep it around because it sort of tests some really new types.
Buying one of those today is a waste of money unless it's really CHEAP and you intend to buy a real checker also.