how vacuum tubes work and testing vacuum tubes

In this episode I go over how to test vacuum tubes. i go over the basics of tube function and testing. the tubes i primarily talk about are 5y3 and 6v6 or the 6l6. with modern electronics most people have little experience with tubes since they are only really used anymore in vintage electronics or guitar amplifiers.

[asterix]

“Some of you who are young might not know who Yul Brynner is.”
I think anyone who’s sitting through a half hour long video on how vacuum tubes work is old enough to remember Yul Brynner.

[stringlesswonder]

Really enjoying your description of how tubes work. I think the word you are looking for at 13:00 about the beam grid is “focus”. Looking forward to the testing section.👍

[mohamedabdullah]

I miss tube days ! Great video, thank you for sharing .

[numberslettersstuff]

Your channel is amazing. Thank you for the random goodness.

[joeirwin]

I'm a newby on tube radio repair, this video helps me al ot, thank you for good common sense explanations

[MightyWhiteofYou]

Awesome explanation. Thanks. Nice and clear.

[Manythings]

I have the same 920 tube tester and as I tested the 6V6 tube my meter also fell about where your did. The tube roll has this statement (6SA7-Amp. Section OK above 1/3 scale). Is the 6SA7 amp. Still a bad tube? Thank you.

[jeanlawson]

I just picked up one from my Aunt's house today and I have no clue what brand it is but the thing is huge....the cabinet and legs were all falling too pieces...any way the speaker has a transformer on it and the voice coil is screwed and so is the this thing has two massive transformer and around 20 tubes half are large half small the radio part itself is about the size of the radio you showed the board itself is about 24 " long and has a reverb I am converting it wish me luck....😜

[qddk]

I am planning to do a little 9-pin preamp tube tester with a fixed freq oscillator, 2 sockets, one for 12AX types and one for 6922 types with the tubes wired for 6.3v.
Configured as common cathode amp stages. If I put say 100 mV in, I would be able easily to calculate the amplification pr. stage.

BUT ... how do I determine if the tube still is very good, good, fair, not good. Does it loose amplification when it gets worn out?

[andrerock]

Very interesting and informative! Thanks!

[oathpendragon]

Thanks..I was confuce in my chapter you helped me! :)

[pbourd]

Couldn’t find the Brad Katalla mentioned in video. I’d like to get tubes tested from a Philco 46-1226 code 122 Radio-phonograph 7AF7 mixer, the tubes include 7AF7, 7H7 (2 ea.), 7C6, 5Y3, 6J5, and 6K6(2 ea.) based on comments I might need to test the passive components too: Caps & resistors. Found the schematic online

[coldfingersub]

Did you rebuild or to put it more specifically did you recap all the capacitors in that tube tester. School that used to repair radios instructor is giving me two of those two testers I open them up and use my capacitor tester on all the old capacitor and all of them were out of value specially the old black paper capacitors. Then I went around and I tested some of the old carbon composition resistors and I found a few of the resistors values were out of range that is common on some of the old carbon resistors. I was watching some restoration videos on how to restore and rebuild tube testers. Some of them take a very specific type of calibrated match paired vacuum tubes that are used internally just for two testing during calibration and then you remove them after all your calibration store them to the side and your two tester will be like new again