How do tube testers work?
The mutual conductance tester tests the tube dynamically by applying bias and an AC voltage to the control grid, and measuring the current obtained on the plate, while maintaining the correct DC voltages on the plate and screen grid. This setup measures the transconductance of the tube, indicated in micromhos.
How can you tell if a tube is bad?
Sometimes you will hear strange sounds, loss of power, or heavily distort sound. These are signs that a tube is failing. Often power loss that seems like the amp is performing at half power or less will be one or more bad power tubes, or even a dying phase inverter tube.
How close should tubes be matched?
We match tubes to be within 5% of measured plate current (that is, the tubes won’t differ from each other by more than 5%, or 1 milliamp in 20).
How can you tell if tubes are good?
Put the tube into your guitar amplifier, tester, or other tube-using machine. Turn on the machine to activate the tubes, and look for an orange, red, or purple glow. If the heated filament inside the tube glows orange like a setting sun, it’s usually a sign that the tube is healthy. The filament may be hard to see.
How long should a tube amp warm up?
20 to 30 minutes
It is important, too, that the warmup that you give your tube amp is very thorough. If they are not warmed up properly, the tone of your playing will not be as good as it ought to be. As a rule of thumb, your tube amp needs to be warmed up for 20 to 30 minutes at least before you can start playing your guitar.
How do I know if my tubes are matched?
To be specific, mis-matched tubes can be bias-adjusted so that output sound is centered. However, if the tubes aren’t a true match, then one channel will not sound as “lively” as the other – sort of like a dead can. With experience, this is easily discernable by ear.
Is it bad to play a tube amp before it warms up?
As a rule of thumb, your tube amp needs to be warmed up for 20 to 30 minutes at least before you can start playing your guitar. Most of the time, tube amps have warm up specifications included in their instructions for use.
What is a TV-7 tube tester?
This is a page devoted to the TV-7 ( )/U family of tube testers. These testers have become very popular for people interested in vacuum tube technology. These are portable units, which a size small enought to carry them easily.
What should I do if the tube tests good or bad?
If the tube tests good, continue the test by testing for gas (q below). Note.
What are the different plate numbers on a TV7?
TV-7 D/U only. 3S Triode No. 1. 3S Triode No. 2. 30 Short on 2 and 3. 40 40 Plate No. 1. 40 Plate No. 2. 12 .93 25 25 15 50 Plate No. 1. .541 Plata No. 2. 40 F basing. Plate No. 1. 66
Who are the best experts on TV-7?
Dan Nelson (new e-mail!) is one of the best known TV-7 experts. Good source for expert repair, calibration and parts for TV-7 and other testers. Highly recommended.