The crude CEW Tube Tester!!

This machine will test QBL 5/3500 (or equiv) and TH328/338 tubes.

Tubes are tested with 1000V on the anode, no bias. A good QBL will draw 1A.

The Thompson tubes are tested for arc-over (most common problem) and emission,
used QBL's are normally fully operational but some have been run down beyond amateur use.

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