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Tube tester

two fingers

two fingers

Opinionated blowhard. But not mad about it.
Inactive
Feb 7, 2005
33,959
116,684
55
Eastern NC USA
#1
So, these days, where would you guys (who are into that kind of thing) go about finding a tube tester? What kind? Who calibrates them (or can I)?

Background: I'm in school for electronics and one of my goals is to be able to hot rod and fix amps, even if only a hobby for myself.

If this is in the wrong spot, please throw it over where it belongs. Thanks!
 
#2
Ebay is usually your friend here or estate/garage sales, sometimes CL. Brands? Hickok, Sencore, Eico. Most you can do a search and find repair and calibration info. No tube tester is 100% and testing methods very. I like my Sencore MU-140 for the Gm, Emission, grid leak and simple "life test". The very best tube tester is the circuit in which it is used.
 
#4
Here's a thread I started on The Gear Page, when I thought about getting a tester. Frankly, after reading all the replies, I decided to let my local tech guy take care of it. :rollno:

Invalid Link Removed
 
#5
The best way to test a tube is at the plate voltage that it will see in service. That's why may say that the best tube tester is the amp itself. All but a couple of testers operate at relatively low plate voltage levels. This doesn't mean that tube testers can't be useful. They can do a lot. I tend to use mine to screen batches of tubes that I get. This is what you want to aim for. Of course, testers like the AT1000 are too expensive for casual use.

What to look for? A mutual conductance tester should be at the top of the list. Hickok and testers and those made by them under other names are good because they are well made and documentation is available. Documentation includes tube charts (these things are useless without them), schematics, and calibration procedures. There are a number of military testers available. One nice one is the TV-7D. It is small and portable and will test any instrument amp tube. There is a guy in NC that specializes in TV-7 units. He might be able to help you locate one but his prices are up there. Many others offer this kind of service, google "tube tester calibration and repair service".

Prices of these tester keep going up. People collect them which doesn't help. One good source where prices are low is hamfests. You can find one in your area here. They are a good source for NOS tubes as well. If you're patient, you can find $100 or less deals on all kinds of test equipment.
 
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#8
You need a VCM 163
Fig1_600.jpg

of course there are other tube testers?, but they just don't tell you anything much about the actual state of the tube you are testing.
This is what we used when I was at college and nobody thought it wasn't the best by a long long way.:bassist:
 
#9
Find an old amp with a good very high voltage power supply, find some surplus rheostats, switches, tube sockets, etc. then build one as a course project and get credit for it. Make everything variable so that you can examine all the operating parameters of the tube. Use a micro controller such as an Invalid Link Removed and interface it to a computer. Make it even better than an AT1000. That's good for more than one project. If you want to go one step further, make it function as a curve tracer.

Approach Loud and see if they will donate a junker SVT that you can cannibalize to build a tester. Yes I know, the temptation to fix it and use it as an amp would be too great. :p
 
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#12
Bassmec said:
You need a VCM 163
Fig1_600.jpg

of course there are other tube testers?, but they just don't tell you anything much about the actual state of the tube you are testing.
This is what we used when I was at college and nobody thought it wasn't the best by a long long way.:bassist:
Click to expand...

Now that thing looks cool. I haven't read up on it yet so that's all I can say right now.

Edit to add: There don't seem to be any for sale here in the states, but I'll keep my eyes open.
 
#16
Hi.

B-string said:
The very best tube tester is the circuit in which it is used.
Click to expand...

^This.

beans-on-toast said:
Find an old amp with a good very high voltage power supply, find some surplus rheostats, switches, tube sockets, etc. then build one as a course project and get credit for it. Make everything variable so that you can examine all the operating parameters of the tube. Use a micro controller such as an Invalid Link Removed and interface it to a computer. Make it even better than an AT1000. That's good for more than one project. If you want to go one step further, make it function as a curve tracer.

Approach Loud and see if they will donate a junker SVT that you can cannibalize to build a tester. Yes I know, the temptation to fix it and use it as an amp would be too great. :p
Click to expand...

And especially THIS^^^

Back in the late 80's/early 90's I was dying to get a tube tester.

I searched high and low, actually long enough that my immediate desire to test tubes practically faded (USSR vanished, and the price of bulk tubes skyrocketed), but one thing became very clear.

There was no such thing as a tube tester for audio use. Not one costing less than a fortune anyway.

If beans-on-toast's suggested approach of gutting a SVT (I was going to suggest the same because of the high enough anode voltage :)) still sounds too complicated or too expensive, folks have built a lot of tube testers for audio use from the simple AX84.com circuits.

Good luck.

Regards
Sam
 
#17
I have two tube testers, one is a Heathkit assembled in the 60's; the other is a briefcase-sized unit. They're around if you search Ebay and other sites...don't know about prices, because I got both free by being in the right place, right time.

Don't get too obsessive about exotic tube testing procedures. A general purpose tube tester will tell you whether a tube is functional or not. Seems like people think tubes are big ju-ju now, but I grew up when every grocery store had a tube tester sitting next to the checkout counters.
 
#20
I like my DynaJet Model 606 tester. Less than $150 on ebay a while back. Tells me Shorts, Grid Emission, and Quality of the new or vintage tubes. I've tossed a few tubes in the garbage before they got put in amps or preamps thanks to this tester. Simple, compact, and useful.
 

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