Since a lot of us utilize tube based gear, I am wondering how many of us own a tube tester? I am considering acquiring one, not sure if I would look for a Hickok or another brand/type. if you are considering a tube tester, or already own one, do tell us your recommendations and your experience with the particular type you own.
My advice is to buy one that is already working and calibrated. Also, make sure that it can test the kinds of tubes that you want to test. Because not all testers are equivalently capable. This will mean that you'll pay quite a bit for a good tester.
I've owned a Hickok 600 for about 12 years now. It was freshly calibrated when I bought it and I haven't had it updated, but it doesn't appear to have drifted too much. I test every tube I get and record the readings, so that I can both compare them after a period of use and compare them to other tubes of the same type. That system has worked well, and I believe mitigates the effects of any change in calibration. I rarely resell tubes so absolute accuracy just isn't a priority for me.
That said, markus is correct; if you're buying one it should be calibrated and completely functional, and that doesn't come cheap these days.
It's a superb mutual conductance tester and was sold to us fully refurbished and calibrated with a warranty. Bud sells many brands of testers, that being his specialty. He is always available by phone or email and very willing to help with any questions or procedures re the tester. I have no financial (or other) affiliation with this company - just a satisfied customer. Highly recommended!
I’ve been very pleased with a Hickok 800A I purchased from an antique radio collector in the 1990s. I’ve never had it calibrated, but testing I’ve performed on many NOS tubes (that I know to be truly NOS/never used) as well as various used tubes, in relation to my antique radio collecting hobby as well as in relation to my audio system, has given me high confidence in its accuracy. And the measurements it provides these days seem consistent with the ones it provided in the 1990s.
In searching for a Hickok or other quality tester it would probably be beneficial to include a perusal of the various antique radio-related forums in your search. And possibly also some of the links shown under "For Sale, Services, etc." around the middle of this page:
I own, and like very much, the Amplitrex tester. It is a modern design that is still in production. It's ease of use is unmatched. One chooses the tube type from a menu, and after a type is selected, the display tells you which socket to use. The machine then warms up the tube before testing. The screen showing the results displays the specification for the tube, which can be compared to test results, and also interprets the results as strong, weak, etc. The tester measures emissions, transconductance, gas/leakage, and noise. The Amplitrex tests at full power to stress the tube; this gives more honest results than the vast majority of units that do not stress test the tubes. A lot of tubes that test strong on a Hickok, for example, will not do as well on the Amplitrex.
For tube types not on the menu, the unit can be programmed to test such other tube types. For really advanced users, it can be hooked up to a laptop and it will then curve trace the tube.
The downside is, primarily, that the Amplitrex is expensive.
I too took the Amplitrex plunge. Yes is was expensive. Yes it was worth every penny. I couldn't live without it.
The bad news? A lot of the tubes we buy are not near as good as advertised. There is no ambiguity with the AT1000, it tells you exactly what you have. Few new production tubes I've bought even comes close to NOS.
Get headphones, plug them into the Amplitrex, gently touch the top of the tube with the eraser of a pencil. It's amazing how many tubes are microphonic.
@ the OP, if you are testing drivers ok, for testing output power tubes not really worth the money Tube testers are old instruments, with degraded parts, right now Roger is trying to rebuild the transformer of a 752 A I sent him some time ago, Roger he is one of the best if not the best, very honest and straight person. With the tester calibrated and ready to go it is advisable to use a variac to supply plate current to the tube so the measurement is more accurate if your tester is old like most are.
Don expect you will be able to measure tubes with high precision, unless you spend a lot of money and time. I own a BK707 too and it is a toy it constantly drifts.
Not trying to discourage you but it all depends on what you want it for. Which tubes and amp / preamp will you be using? How often will you be measuring?
I've also owned an Amplitrex AT1000 tester for around 10 years now, and have found it to be completely reliable, accurate and easy to use. Yes, it is expensive, but well worth the money if you are a serious tube audio enthusiast. As mentioned above, a lot of very well known tube sellers are selling both NOS and new production tubes out there which often do not test anywhere near what they claim they do, and use old testers that give confusing results that they try to dupe buyers into believing they are getting more than they really are. Don't fall for the "platinum matched" scam presented by some sellers who charge a lot of extra money for their tubes, claiming that they match within a few percent of each other, when in reality, they are off by as much as 20 or 30%.
I had 6 at one time back when I lived in my home in NY. You could say I was obsessed. Included were the Western Electric KS-15750, Triplett 3444, Hickok 539C, TV-2 C/U, TV- 7/DU and Hickok 752A. They were all stellar performers. The Hickok 752A was the easiest to use because you could check both sections of a tube with just a flip of a switch (you didn't have to change all the settings). My favorite was the Hickok 539C. I sold them all but my TV- 7/DU making my retirement move into a condo. I kept the TV- 7D/U because of its small compact size, and it's very rugged.
Maximatcher II preamp tube tester. Easy to use and repeatable. For power tubes, I just buy new tubes instead of spending the money on a tester. My amp uses KT-120 tubes. For the price of a tester I can get a complete new set of matched tubes.
I bought a TV-10Du that was supposed to be in perfect working order from someone on ebay. It arrived dead. I thought it was probably something loose I could fix, but never could find anything obvious, sold it at a bit of a loss. Then bought an Amplitrex, terribly expensive, but it works. As they say, buy good, cry once
If you’re really serious get the Amplitrex AT1000, about $3000
If you can live with less precision and control but want a modern computer type tester the Maxipreamp 2 is about $1,000. It will not test power tubes.
If you want a general idea if your tubes are good or bad and are reasonably matched get a home grade Hickock or TV-7DU for a few hundred $. You will not get repeatable results from these testers. Each time you test a tube you will get somewhat different results. These were basically designed to be good/bad testers for the TV repairman to bring to your home to replace tubes in your TV, console stereo or radio.
The lab grade Hickocks, 539C, 752A and others will give more accurate results and more control over the testing parameters, but will cost more than home grade and require quite a bit of learning to use them properly.
Also, the 6DJ8, 6922, 7308 family stresses out most home grade testers except the TV-7 family and you cannot get good results from most home grade testers. The results just go off the charts.
I am not an expert and if any of the above is incorrect or incomplete, please correct me.
If you want a general idea if your tubes are good or bad and are reasonably matched get a home grade Hickock or TV-7DU for a few hundred $. You will not get repeatable results from these testers. Each time you test a tube you will get somewhat different results.
FWIW I haven’t found that to be the case with my Hickok 800A. In fact on a number of occasions I’ve recorded measurements of a given tube, then repeated the measurements after many months of light to moderate use, and obtained essentially the same results.
I’m very careful, of course, to set the "Line Adjust" and other adjustments on the machine ("Bias" and "English") accurately, and to allow both the tester (which contains one or more tubes) and the tube under test a sufficient amount of time for warmup.
Al, thanks for your experience. What do you mean by essentially? I mean that you may not get a radical difference but you won’t get the same reading either.
I’ve been told by Roger Kennedy that the spec for a new (and there aren’t any new ones anymore), calibrated Hickock home type tester for Gm is +/- 15% That means that two testers both within spec can have a 30% difference measuring the same tube, worst case.
It’s also necessary to remember that most of these testers contain tubes inside the box with no ventilation, so how long the tester has been on affects the results. I’ve been told to never leave them on for more than an hour.
The Maxi-preamp 2 tester has an adapter for testing 6DJ8 family tubes but it still has the problem of the tube overloading the tester.
@mofimadness That's an interesting option. Any idea as to what that sells for? Also, I wonder how accurate that Orange unit will be with power tubes? A few years back, I took an ARC amp to a local tech who tested the 6550's that the amp utilized. I thoughts something was wrong as the amp was noisy in one channel...and the tubes were not new. He tested the 6550's on his Hickok and pronounced them healthy. Turns out that they were anything but, so after a near melt down..and a full tube replacement, the noisy channel issue was solved. Since I am now using KT150's in my amps, I would like suggestions as to an amp tester ( besides the pricey Amplitrex..which I am sure is excellent!) that can accurately test these tubes.
I use a Sencore's grid leakage test to find tubes that otherwise test fine for emissions including fine on Hickok testers. Let warm sufficiently for 15 minutes or so before test...i used to also have tubes that tested fine in my arc preamp, but were clearly not so...the sencore now catches those tubes.
I would back up that statement about checking on Roger at Alltubetesters. Let the Buyer beware... I currently own a Hickok / Western Electric KS15560 rebuilt by Paul Hart in Atlanta, he is an Electrical Engineer (retired) and does great work, he has a number of testers he can rebuild to sell (firstname.lastname@example.org). Also own a Hickok 752A (rebuilt by Paul) and Jackson 658. One thing about Paul is he can modify a tester, mine have been modified to run with a Variac which increases the accuracy on all tubes, especially high heater current tubes because there is no loss in the line adjustment pot. Mine can also can measure plate current. As daveyf above says, if you want to test at 600 volts you'll need a specialized, modern tester. Mucho $$$$. But the older Hickoks, if calibrated, do a fairly good job within their voltage limitations.