Updated on 19 October, 2021
When I was in high school I had a science project and I needed a vacuum tube tester. I went to the local junkyard and purchased a black and white vinyl one that was about three inches square. I got lucky as my teacher, Mr. Jones, had one of the best units in his classroom. I used it everyday for a year and then sold it to a friend. But I still had the black and white one which worked fine.
As I mentioned above, vacuum tubes are made up of four to seven different chambers. Some have characteristic curves in them. They are called characteristic curves and are important to the performance and efficiency of any pump or heater. The curves in a tube can either be positive or negative and are a measurement of the pressure and speed of the moving air. Vacuum tube testers can measure these curves and report their findings on a numeric basis.
The other most common characteristic curve is the anode current. This is usually set at zero for non-vacuum tubes. The anode current can be measured with the anode magnetron although this has become obsolete and is not recommended today. High school students, however, can use this instrument when they demonstrate their assembly skills.
Other characteristics of a tube include its electrode, the number of times it has been turned on and its total discharge or emission. There are two types of electrodes, the permanent magnet DC input and the variable pulse AC input. The permanent magnet DC input is the only one that can provide current through the entire tube so this is the type of electrode used for the anode tester. The variable pulse AC output is connected to a small battery and is measured as the voltage across the terminals. The size of the battery will depend on the power consumed by the device.
The tube is sealed in a top cap made of thermally conductive material. One of the main features of the top cap is that it can be opened easily using a screwdriver so that both the input and the discharge of the electronic device can be observed. The electronic device itself will consist of a positive and negative wire and may include a diaphragm and metal threads to allow the passage of the air molecules through the tubes. The wires can be connected in either direct or alternating currents.
The measurement of these voltage levels is achieved through the use of electrodes attached to the tubes. The length and diameter of the electrodes should be such that the diameter of the opening of the bulb connected to the device will correspond with the voltage level measured. It should also be noted that the thickness of the wires will have an effect on the results. The smaller the opening of the bulb, the smaller the amount of current flowing through the tube.
For accurate results, the wire connections should be varied according to the tested load. A mutual conductance tester is useful in measuring the voltage across the two grids. This testing procedure will be carried out with the device connected between the positive and negative rails. In most cases, a small current will be seen passing through the device. However, if the results are varying, the frequency may be too low.
The purpose of the continuity tester is to confirm the readings obtained from the other methods. In order to measure the voltage across the two conductors, the continuity tester is used. In most cases, the terminals of the appliance will be connected to the outside world through an electric socket. Thus, the apparatus will need to be attached to a load that can provide the voltage required by the appliance. The load will act as a source of alternating current to the electrodes, which causes a current change.