Tube tester suggestions?

[dtvmcdonald]

Our department used to have a wonderful tube tester ... but somebody
threw it out. Luckily they didn't throw out the tube stock.

So I'm in the market for one. I'm asking for advice. I'd really like to
get one that could test, at least for emission, older tubes. A post I found
here claimed that going beyond emission tests is really unnecessary
for purposes of fixing sets (as opposed to, for example, matching
pairs of tubes for push-pull audiophool amplifiers). Do you agree?

I'd be happy to use a socket adapter for pre-octal tubes if data were
available for them.

There are numerous ones on eBay for various prices ... I really don't want to
pay more than $250, preferably not more than $180. So what I want is
advice on if I should snap up one available now on eBay, look in
other places (e.g. the classifieds here) or, probably most important
since I'm in no rush, wait for a few really good models on eBay at the
right price.

Advice wanted.

Is should add that of course there must be such advice in earlier
threads right here ... but the search function has not revealed a really
good such thread, maybe there is one that the old-timers can point me to.

Doug McDonald

[Electronic M]

Best place to get one is an antique radio club or ham swap meet.
I keep a B&K dynajet 606 for octal/loctal to end of the tube era compactrons which works quite well. I work on any TV with tubes so every socket on it gets used.

The dynajet though don't test anything pre-octal so at a MARC Extravaganza meet a year or two back I bought a restored Heathkit tester for 40$ which has the early sockets. It is nowhere near as good a machine as the B&K, but on the early tubes it gives me a far better idea of performance than tube swapping (my testing method before I had it) ever did.

[bandersen]

There's a family of good all around basic emission testers that share a common design. So similar you can use the same tube setup chart with all of them I've heard.

Triplett 3413
Heathkit TC-1, TC-2 or IT-17
Knight 600
ECIO 625 / 628

I'm sure there are others I'm leaving out. Personally, I used a Triplett 3413 for years and found it to be very reliable.

[earlyfilm]

Originally Posted by bandersen

There's a family of good all around basic emission testers that share a common design. So similar you can use the same tube setup chart with all of them I've heard.

Triplett 3413
Heathkit TC-1, TC-2 or IT-17
Knight 600
ECIO 625 / 628

I'm sure there are others I'm leaving out. Personally, I used a Triplett 3413 for years and found it to be very reliable.

Bob,

I agree with everything that you have said, except "they all use the same tube setup chart."

Yes, they are all based on the same Triplett circuit.

I own a Heathkit TC-2 and a Knight 600 and the tube charts are completely different. Allowing for the different switch numbering, the test scales are different.

My Knight 600 is over 50 years old, and it worked fine until about 5 years ago when the capacitor in the shorts test circuit started leaking enough to make all tubes fail the short test. Replacing that one capacitor solved the problem. The only other thing ever done to this tester was to clean the switches and sockets with a traditional non-Oxy type of contact cleaner. (The Oxy type tends to collect dirt.)

James

[bob91343]

I have two testers, a Precision emission tester and an EICO mutual conductance tester. The Precision is all I need. The EICO works but frankly I don't see a need for it. I have used the Precision for many years without issue and it's my tester of choice.

I don't feel that a transconductance tester offers anything useful in testing tubes for use in existing circuits. It might be a good tool for design and development, especially of tubes themselves, but if a tube passes emission and short tests on a simpler tester, it's probably just fine for the circuit.

[wkand]

There is a test that I have found to be very useful on newer tube types with fragile structures (like multi section miniature and compactron types), called grid leakage, some say grid emission. I believe those to be the same thing. it is a detection of current flow between the control grid of the tube and other tube elements when the tube is properly biased from control grid to cathode. this test could indicate worn out elements in the tube or it could indicate a tube that may be NOS that has been sitting on the shelf for a while. It is not an absolute indication of a defect, but for most tubes, in a properly calibrated tester, it is usually an indication of a worn tube. Sencore TC series (TC162, my personal fav) testers have good circuits for this test. I have a newly acquired B+K tester (from the 1970's) that also has this, but not sure how reliable it is.