Tube tester?

Build your own. I have schematic, parts list, cad dwg and PCB.

PM for more info.

I’ve been ’into’ tubes since the 1950’s w my Dad’s Bogen. I always wanted a tester. Many testers don’t actually test in operation range. I considered the µTrace, but it’s more of an engineer or amp designer than hobbyist’s tool. Hence, the tester shown above.

I have a pal that manufactures tube gear who lives a couple of blocks away. He has a Hickok which showed good on a KT88. Sonically, it clearly wasn't, so dammit, design and build one that can test in actual operation! Results below.

It can easily be modified to include 2x 9 banana plugs and as many sockets as desired to test almost any tube. In 50+ years of tube amp ownership, every tube I’ve owned can be tested in just the two sockets installed.

Depends on how old the tube is and how long it sat on the shelf. Testing NOS that have sat for decades will almost all certainly fail a gas test.

Even new tubes that have sat around for a couple of years may fail the gas test.

Tubes that fail a gas test often recover after 10-20+ continuous hours on the heater. If it doesn't, it likely never will. Some tubes may test gassy after weeks of inaction if they have pin/envelope micro fractures from repeated insertion cycles or 'porous' glass.

As far as sonics, all bets are off. Tubes vary immensely. A particular tube may sound fine in one circuit and not well in another. Additionally one tube may drag down its siblings in a circuit or channel.

AudioPhools lack of evaluation rigor makes most recommendations specious.

Schematic, BoM, CAD dwg w dimensions and build photos for

available @ ieLogical Valve Tester