Quote:
Originally Posted by Charlie
. . . . . going through boxes and boxes of tubes . . . . I allow a tube to warm up for 8-10 minutes in the tester. Many times, grid leakage doesn't show up for several minutes. Since I've started this, it seems on average that I end up discarding 1 in 4 tubes.
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Charlie, if the tubes are used pulls, 1 in 4 with grid leakage is expected.
If these tubes are NOS, suspect that the short indicator on your tube tester has become too sensitive due to the resistor-capacitor circuit that the gas test uses. A slight leakage in the capacitor will usually result in good tubes showing leakage.
For the record, in the 1950's, blank generic boxes (especially with the Standard-Brands design) could be bought for a few cents each (with or without the white space for the tube number) and a rubber stamp used to create fake labels. I used the numbers and letters from an old toy printing press and made hundreds of these replica tube boxes. We sold these tubes at a huge discount as tested used tubes.
Most of the tubes came from junked trade-in sets from the dealers that contracted their service work from us. This worked out fine, as most of the do-it-yourselfers had older TVs. With that said, the fastest movers were the 5 tubes used in the all-American 5 radios.
Jas.