01-15-2017, 02:13 PM
Take your 201As and test them at 5V on the filament - no, not what the switch says - with a volt meter on the filaments - like Arran said. While the tube tester may be designed to accommodate the voltage drop, this is still meaningful for normal operation from a 6V battery.
If they don't put out ~ 450 mho, you can run them at 5.5V - yeah with a volt meter - for a few hours. Then run them at 5V for a few hours. Then test again. You can learn some by pushing the test button at 5.5V. That is - that if the emissions go up it is possible that this process might revive the tube. If the emissions do not go up at 5.5V you are probably wasting time. This IS NOT the conventional rejuvenation process for thorium impregnated filaments but for thorium coated filaments.
If they don't put out ~ 450 mho, you can run them at 5.5V - yeah with a volt meter - for a few hours. Then run them at 5V for a few hours. Then test again. You can learn some by pushing the test button at 5.5V. That is - that if the emissions go up it is possible that this process might revive the tube. If the emissions do not go up at 5.5V you are probably wasting time. This IS NOT the conventional rejuvenation process for thorium impregnated filaments but for thorium coated filaments.
