Testing tubes without a tube tester???

tube tester basics

Hi Folks!
Dumb Question #1: How can I test vacuum tubes without a tube tester? Namely, 6AK6, 6BE6, 6HR6, and 12AX7.

Dumb Question #2: Is there a solid-state equivalent to these tubes? They are from an old Knight Star Roamer that keeps dying.

Dumb Question #3: Is the above worth doing?

Thanks for your help.

tube testing without a tube tester

dumb answers (':lol:') to your highly useful questions

1. If the basic radio is working you can use it to test the tubes. Does the radio function when new ones are put into the sockets. If the radio is not working you can make a tube tester which would cost more than buying a new radio unless you have the parts in your junk box. One basic test is when the heater is powered and a low voltage is applied between plate and cathode measure the current. This measures the emission of the cathode. Slightly more complex is to make an audio amplifier and measure the audio gain with each tube in the socket.


2. Because of the high voltages, it takes special parts to simulate the tube performance. They are expensive if attainable.

3. As a result of 2 above and if you cannot get cheap replacement tubes, buying another radio would probably be cheaper.

You might try finding out why the tubes fail. One possibility is heater voltages too high.