Quick Test for Electronic Tubes

A friend was at a yard sale and bought a facsimile antique wall telephone that was really an AM tube radio. The radio did not work. I used a simple way to test the tubes and fixed the problem.

Step 1 Tube Circuitry

Until the late 1970s many drug stores and electronics shops sold electron tubes. Those outside the USA know them as valves. Each store selling tubes usually had a tube testing machine with several dozen tube sockets and various charts to find the right data for your tube.

Below is the electrical diagram for a typical tube. The filament heats up when current flows through it. When heated by the filament, the cathode emits electrons that are attracted by charge to the anode. Various grids insert signal charges, often fluctuating, to restrict or speed the flow of electrons to the anode.

Although there are a number of things that can go wrong in an electron tube, one of the most common is that the filament burns out.

Comments

[dataphool]

Although you have described the pins as the first two, the pin numbering system counts the pins in a clock-wise direction, so the pins you are referring to are 6 and 7. What about a 12AU7 which has 9 pins, or 6L6 which has 8?

You have a good i'ble, but I don't think anybody cares about tubes anymore. Except audiophiles, who are a little strange anyway.

[Phil B]

Thank you for the corrective information.

[master key]

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[master key]

Slam on the brakes for a minute did She replace the paper capacitors with brand new capacitors and don't for get the resistors they tend to float above there resistance but this is a great way to test tubes

[Phil B]

Thanks. It worked out well for me as a diagnostic tool when I needed it, even if it is not a completely reliable test in all cases.

[wierd idiot]

now sorry to say but this method can be unreliable because you can get mutable pins that have ohms measurement but the filament could still be blown.