Buying used Tubes

In a single word, DON’T. If you must buy used because new tubes are no longer being made reconsider the advisability of continuing to use the equipment requiring that tube. If you still want to continue with the tube purchase try to get some sort of guarantee.

Broadcast and medical pulls still have considerable life left and can be good values as used as long as the price is less than half what a new tube would cost. Used tubes are not worth more than half the price of a new tube and possibly less than that.

Tubes that are still being manufactured and available as new are always preferred as long as they are exact substitutes for the tubes being replaced. Note that there are tubes being produced by foreign companies that claim but do not provide compatibility. Among these are 572 and 811 and, no, you can’t rely on the new spec sheets. Look for help on the internet from people who have already been burned.

Normally you should have no problems buying from reputable suppliers like R.F.Parts. They provide a warranty and money back guarantee.

Under no circumstances should you buy anything that may require filament or cathode conditioning. In fact I would not waste my time on these even if they were free. The chances you will end up with a dead bulb are too great.