Introduction: SImple Valve (Tube) Tester
A valve tester is nothing more than a set of adjustable calibrated power supplies, a meter to measure to current and a set of sockets into which the valve under test can be inserted. However when I started to look for a second valve tester I found them incredibly expensive, I therefore decided to make one.
The valve tester shown here has an adjustable HT supply (upto 300V), an adjustable negative supply for grid bias (upto -50V) and a heater supply.
The HT supply is just a simple cathode follower, based on a circuit from Radio Constructor by G A French. Initially I was going to have a switch on the voltmeter to monitor grid voltage as well as anode voltage but in practice it was easier to use my DVM.
The valve tester shown here has an adjustable HT supply (upto 300V), an adjustable negative supply for grid bias (upto -50V) and a heater supply.
The HT supply is just a simple cathode follower, based on a circuit from Radio Constructor by G A French. Initially I was going to have a switch on the voltmeter to monitor grid voltage as well as anode voltage but in practice it was easier to use my DVM.
Step 1: Notes and Pictures
I used valve data for an AVO valve tester when testing valves, any valves that required a heater voltage other than 6.3V I used a seperate power supply. The EL81 is also overrun with some valves, this has not caused a problem. In use I manged to damage the milliammeter due to faulty valve, I plan to put a diode across the movement in future to help prevent this. I also found that the odd valve would oscillate at high frequency.
