Sencore MU-140 Mutual Conductance Tube Tester the 'Cadillac' of tube testers.
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- Опубликовано: 2 окт 2024
- A very clean Sencore MU-140 mutual conductance tube tester. This was Sencores best and latest right before transistors took over and tubes almost went the way of the dinosaur. B+K also made the BK 747 MU tube tester and these 2 are considered the Cadillac and Lincoln of tube testers. Yes, there are a couple more very exotic and expensive tube testers that best these, like the Hickock TV7 'military' tester but those don't test a wide variety of tubes and are very expensive. The TV-7 maybe the Rolls Royce of testers.
Anyway, with most common tube tester's, they only test emission. When the filaments in a tube heat up the cathode, the cathode emits electrons. Hence, a common tube emission tester tests just that or should I say only that. An 'emission' tester tests the amount of electrons the cathode emits. Thats a good test and usually the output of a tube will match the 'emission', but not all the time. A Mutual Dynamic test actually applies a signal to the grid and test's the real output of a tube. Hence, a MU tester will be a lot more reliable, accurate, and will catch a lot of bad stuff a standard emission tester won't.
Leakage tests is self-explanatory. A leaky tube will cause all sorts of bad havoc in a radio and often is hard to trace in circuit because the leaky tube often has good output. Hence, I always not only test tubes for emission, and MU, but for leakage too. It's a little bit painstaking, especially if you have a lot of tubes to test, but the end result is often well worth it.
This tester is in great shape, almost mint. Hard to find one in this good of a condition. Very clean inside and out. Only thing done to it was a cap job and an alignment and away it went. This was one of the last of the tube testers made and one of the best. BTW, this tube tester actually uses 2 internal tubes in it along with a few transistors. A little tid bit from the tube guru's is that is competitor, the B+K 747 tube tester, is all transistor, no tubes. The tube people back then say they knew the handwriting was on the wall, because there was know a tube tester that doesn't use tubes. They were pretty much right, but on the other hand, as much of a pain as a tube radio or amp can be, there is nothing made, yet, that sounds like them. Even my non technical wife who couldn't care less about this kind of stuff, still loves the sound of my tube radios and tube stereo over any transistor stuff I have. Long Live Tubes.
Beautiful piece of kit right there now...
Very clean, almost new looking! 😮
I've been starting to look around for a tube tester. I have fell into the world of old tube radios and amps! 😂
How could I contact you?
You can email me at Tramdr at Yahoo.com
One day I was looking up my grandpa's tram radio and a silent death video popped up you taught me a lot about tube amps
Glad I could help
@@tramdr you the man
brother you got the filiment on 25v its socket 25 the 12v stays the same on both tests. the life test wont budge on 25v lol
wow getting old really sucks.
actually on 2nd thought, you are not correct. The socket on this tube tester does not determine the filament voltage at all. The different sockets determine the different pinouts of different tubes, but not the filament voltage. Yes, in the past, I have seen tube testers where the socket determines the filament, however, this is not one of them. On this one, the filament select 'A' is the only thing that determines the filament voltage. Nice try though. BTW on my 6lf6 tube tester amp that I converted from a 2 tuber to a single tube tester, I did that too. Left both the twelve pin sockets in it, but converted one socket to 6v and the other socket to 12v. That tester works great for me.