I got several old appliance tubes. How do I know if they are good?
There are two possible tests for tubes. The filament test and the emission test. Using the multimeter you can do the filament test. For this you must enter one of the tube manuals that we have available for download and find out which pins correspond to the filament. Measure the resistance with the multimeter. It should be low (between 5 and 100 ohm). If this happens, at least the tube is not blown. The emission test requires special devices that apply high voltage to the tube. This can not be done easily. So simply discard the tubes that are with the burned filaments and leave the others to test on the device itself that will be mounted.
