Need to Test Vacuum Tubes

Electronics
1

I have two Hytron VT-25 tubes that I pulled out of my grandpa’s old Tesla Coil and I was planning on selling them at some point. However, I don’t want to rip someone off by selling them without at least testing them to be good or bad.

Is there a tester available, and someone who knows how to use it? I’m not a paying member any more, so I would need a kind soul to volunteer to help me out of the goodness of their heart.

Side note: if anyone is interested in buying some old vacuum tubes, I’ve got a few that may or may not be in good condition.

IMG_1048.JPG2448×3264 1.27 MB

2

Fred donated a tube tester, which is sitting in my garage awaiting repair and refurbishment. Other then that no, we do not have a tester; however, with a little research you can find what the testers do and replicated those tests with equipment we DO have.

3

my old professor use to refer to those as “watt-sucking fire bottles”

1 Like
4

Don’t insult the tube. They are beautiful creatures that were supplanted by a fad…

3 Likes
5

You had me a Tesla Coil :tesla:

1 Like
6

Hah! Part of why I decided to part out the old Tesla coil instead of attempting to fix it and “fire” it up.

7

A few more decades and that fad will surely have played out.

8

I am hoping, but bright shiny things keep attracting the children…

1 Like
9

Can’t help you with testing the tubes, but a picture of the tesla coil would be neat! Heck, I am sure there are several of us who might be interested in the tubes and tesla coil as an assembly…:sunglasses:

10

try contacting DAVE - the guy that has a bunch of Fred’s gear in his garage - I gave him a working tube tester…

1 Like
11

I have a US Military TV-7 Tube Tester that can test this tube. The VT-25 has a commercial equivalent of a #10 tube, this tube has a 7.5 volt filament. I am in the process of doing some repairs on my tube tester, replacing some broken tube sockets. When finished I can test your tubes.

12

When you do test the tubes, would you be willing to teach a class on it? I’d be interested in learning the process and understanding the types of tubes and how they might be used, too.

Fred had a large number of tubes in his inventory. I ended up with some of them because I was looking for Nixie tubes for a project. Amazingly, I found a single Nixie in the lot.

I’m sure others ended up with tubes as well. Perhaps it would be fun to build a radio using them. One of the engineers in my office has a preamp he made in the 70s from tubes. He says it produces better sound than solid state amps.

13

I have most of them, and I inventoried them. Anyone interested IM me and I will send the spreadsheet. They are free to anyone who would like them.

14

I have not inventoried the few that I have, but I have determined that only one of them is a Nixie tube. Can you send me your spreadsheet please? Maybe it will inspire me to add mine to the spreadsheet.

Did you find any Nixies?

15

The Military TV-7B/U that I have is called a Dynamic Mutual Conductance Tube Tester. This model is highly sought after and sells on eBay around the $300 - $500 range. Over the past 45 years that I have owned this unit I have checked all sorts of audio, television, transmitting, and other tubes, but never a nixie tube. Check the tube listings to see if a nixie tube can even be tested on this unit.

For a listing of all the tubes that can be checked see: TV7

Your suggestion of a training class sounds like a great idea. First let me re-calibrate my tester and we’ll see what the next step is.

1 Like