Sylvania 140 tube tester
 

I was just wondering if anyone else here has or had owned one of these. They were produced in the late 40s, so we know the limitations. I did find a .pdf file with scroll updates taking me into I believe the early 60s.

This was my first tube tester and I bought it for a song in the early 80s when almost anything tube was junk. It has performed flawlessly ever since. I have seen a lot of testers and have quite a few, but I have never run into another one of these. The dial glass broke years ago, so I have to be very careful with that until I get another piece of glass. Probably just go have one cut.

There is one on Ebay for $89.00, so they are out there. I wasn't looking for one though. More just seeing what other people know about them. The one for sale is listed as a "Dynamic tester" which is I don't know for Dynamic Mutual Conductance. I don't see evidence that this is a D.M.C. tester as there is nothing but the usual controls on it. No micromho, english,or other indication of anything but emissions tests, but who knows. My "state of the art B&K Dynajet 747B has none of that either and is supposedly a D.M.C. tester. The 747B in all it's solid state glory seems to be a good, bad, shorts, and grid leakage tester. Maybe a topic for another thread.

The old testers like that are great for vintage radio, 50s TV, and from what I hear guitar amp tubes can be tested on them. There must be settings for EL-34s out there which I'm sure are just based on a similar vintage tube. I think a lot of amps use 12AX7s as well which have been around forever.

I used to have a Sylvania 140 for a number of years. It is indeed a Dynamic tester, not Dynamic Mutual Conductance. It is supposedly better than a simple emission type tester but not as good as a mutual conductance tester. From what I have found it is basically a re-packaged Jackson 648.

There were a lot of testers that seem to be in between a pure emissions test and a full mutual conductance test. Usually they appplied a voltage shift to the grid, so you do get some indication of how the grid affects the plate current. If you have to push a button to get the reading its usually a tester of this type. testers like these will catch tubes that have grid issues better than a simple emissions tester that just tests everything as a diode. If you cant afford a Hickock, they can still be a useful tester.

OK, wow; I didn't know that there was ever a go between although some of my descriptions may suggest that. The Sylvania seemed like a little more than average, but lacked some of the gadgets that I find on my Hickoks' which I have enough of. The Sylvania is frankly easy to use and has always proved to weed out bad tubes.