by AmadeusMozart » Sat Jan 04, 2014 3:36 pm
The following is my personal opinion - I 'm disclosing that I have repaired tube testers, have build one and now am building a pre-amp tube matcher.
Tube testers get silly prices these days, perhaps because they are not well understood. For hobby work it is hardly ever needed, indeed the original purpose was for a service technician to quickly determine if a tube was working or not. Some of the better tube testers are still not laboratory grade which is required if one wants to match tubes. Power tubes have to be tested after they have been heated up for a while at voltages for the expected application. How many tube testers are around that will allow you to set the voltages that your amplifier is going to work at?
Pre-amp dual triodes, especially when they are the first tube in the amp should have sections that are matched, especially in amplifiers that have no feedback. Hence that I am making my own matcher (note not a tester which includes testing for shorts) - a simple setup is sufficient: filament supply, an adjustable negative grid supply, an adjustable anode supply, three digital voltmeters: one for the grid, one for the plate voltage and one for the current. Total cost is around 100 USD which is less than is often paid for just servicing that old tube tester.
Go out and make your own if you need one!