How to Test Vacuum Tubes
A vacuum tube is an electrical device used for creating, amplifying and modifying electrical signals. They function by controlling the electron movement in a low pressure environment such as low pressure gas or in a vacuum. A vacuum tube consists of a glass (sometimes metal or ceramic) tubular envelope with electrodes inside it, in a vacuum atmosphere. If you want to test a vacuum tube, there are plenty of vacuum testers on the market. All you have to do is follow the right procedure for using a vacuum tester.
Other People Are Reading
Instructions
-
-
1
Identify the type of your vacuum tube by looking for printing on the side of the tube. The type of vacuum tube will determine the which tube socket and which switch setting on the tube tester are to be used. Tube designations typically start with a number and are followed by letters and numbers, with the first numbers often being the filament voltage required for the tube, such as 6L6 and 12AX7.
-
2
Insert the vacuum tube into the proper socket on the tube tester as indicated by a chart that came with the tester. Inspect your vacuum tube for signs of damage to the glass or bent pins.
-
-
3
Turn on the vacuum tube tester. Set the test switch positions for your specific tube according to the tube tester's chart.
-
4
Note the "Gm" reading on the vacuum tube tester's meter. Compare it with the acceptable reading for the specific tube as indicated by the tester's chart.
-
1
Tips & Warnings
If you are unsure what to make of the Gm reading, check the Internet for tables that show typical reading for different kinds of vacuum tubes.
There are two basic kinds of vacuum tube testers: a simple emission tester and a mutual conductance tester. The emission tester will only show if the vacuum tube is usable and working. A mutual conductance, on the other hand, will actually measure the plate current and indicate a Gm reading, also known as trans-conductance (mA per volt).
Be very careful when working on vacuum tubes because they tend to get hot.
References
- Photo Credit Old vacuum tubes image by Dmitry Rukhlenko from Fotolia.com
