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valve tester

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Thunderchild

New Member
My dad is planing on saying fairwell to his redundant valve collection. We don't know though if they all work. what sort of a valve tester can I make ? does anyone have a circuit diagram ?
 

Thunderchild

New Member
oh dear all kinds of valves, he has rectifiers and all sorts of radio and TV valves, some date back to the 1920's. I expect we have more pricing clout if we can say whether they work or not, he's not used any in years and some were bought new but after all these years you never know
 

Mike_2545

Super Moderator
I remember seeing valve (tube) testers in the pharmacy when I was a kid. People would bring in the parts, plug them in and test them to see if they were good or not.

Haven't seen one in years.

I guess the best way to test them would be to build an appropriate circuit and put them to the test.
 

Thunderchild

New Member
hm yes well I don't do valves so I wouldn't know how to make a circuit with them and with all the different types I'd be cluless. My dad won't know anymore how to build one and if he does its probably......using the suspected valves (thats is we can find the 1 in 1000 we need for the tester)
 

Rolf

Member
Tube tester

My dad is planing on saying fairwell to his redundant valve collection. We don't know though if they all work. what sort of a valve tester can I make ? does anyone have a circuit diagram ?

I would not attempt to build one! Setting up all the different filament, grid and plate voltages to the correct socket and measure the correct conductance and comparing it the the norm is virtually impossible!
You are better off buying a used one, here is one:
**broken link removed**
Try to get one that has a owens manual.

P.S. Any instrument with electrolytic capacitors in the power supply that has been out of use for a long time needs to go through a proper healing process before use.
 
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Thunderchild

New Member
yikes exspensive, at that price the buyer can test them.... or maybe I can borrow one. I always thought there was a basic circuit used for some valves that was pretty much universal. most of the valves are radio and some TV so its mostly amplifiing valves
 

duffy

Well-Known Member
If the user has to test them, you lose your pricing. Might be helpful to identify which tubes aren't available (many of them still are) and what prices are like, find out if you have something rare and in demand. That $130 Jackson Tubetester may look like a good investment afterward.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
We used to have a valve tester at work, an Avo one if I remember correctly? - it was destroyed in a fire.

Huge thing, must have cost a fortune, and used plug in cards to select which valve you were testing.

They aren't really much good though, they only do basic tests, and only give an indication if the valve is any good or not.
 

colin55

Well-Known Member
The best way to test a valve is to plug it into the equipment.
They way we tested 6U9, 6X9 values was to plug them into the circuit and let them warm up. Then pull then out, count to ten and plug them back in again. If the picture on the TV was grey and gradually got darker, the valve was weak. Now, how are you going to get that kind of sophistication from a value tester?
The same with 6GV8's etc etc 6BH7, and all those numbers I have aleady forgotten.
 

duffy

Well-Known Member
Wonder if there's enough people using tube amps to make a USB tube-tester a viable product?

Probably need to have to have a separate power supply, the filament alone on some of those tubes pull more juice than the USB is rated for. Need a bunch of sockets, a high-voltage power supply, microcontroller, USB cable, plastic box, lot of high-voltage switching transistors...

Maybe a scaled-down version that just checks the most popular tubes still in use today. Limit the filament to a couple of watts so you can run it off USB power.
 

Mikebits

Well-Known Member
Here is the latest in Valve testing technique :)

**broken link removed**
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
Please explain.........

They only do very basic tests, the only way to test it correctly is by putting it in its intended working circuit.

We used to get people taking ALL the valves out of their TV and bringing them for testing, the clever ones made a note of which one went where! :p
 

stevez

Active Member
As already stated, a tester will only give you some basic information though some buyers may pay more for a tube that passes the basic tests.

You might make a very simple tester to test the filaments though you'd have to look up the pin diagram and voltage for each valve/tube. Still it ought to be fairly simple and allow you to offer the buyer that much.
 

Rolf

Member
Did you not read?

They only do very basic tests, the only way to test it correctly is by putting it in its intended working circuit.

We used to get people taking ALL the valves out of their TV and bringing them for testing, the clever ones made a note of which one went where! :p

So the OP should go out and buy a stack of obsolete consumers electronics equipment in order to test his stash of tubes (valves)?
Ridicules!!!!!!!!!!!!
Tube checkers are not perfect because they test static and not dynamic performance. But they are perfectly adequate 99% of the time.
How do I know, I used them almost every day for more years then I can recall.
 

flat5

Member
Tube testers were built to various levels of sophistication.
I used to have a Hickok variable mu tester that was of practical use. It did various tests. At least four that I remember. Tube testers are not perfect but can be very helpful in many cases.

Also of great value (worth a lot to a collector today) was a voltmeter with tube sockets on it. Around the sockets were pins so you could plug a cable with a tube socket in to the equipment under test. Plug the tube into the tester and measure circuit voltages at the tester. Guess it was not great for high frequency circuits but was really cool otherwise :)

It would be interesting to build a tube tester using a micro processor to set up the specifics, using a lookup table in rom perhaps.
 

Mikebits

Well-Known Member
It would be interesting to build a tube tester using a micro processor to set up the specifics, using a lookup table in rom perhaps.

Now there is an untapped market. Dude your on to something :)
 

Nigel Goodwin

Super Moderator
Most Helpful Member
So the OP should go out and buy a stack of obsolete consumers electronics equipment in order to test his stash of tubes (valves)?
Ridicules!!!!!!!!!!!!

Personally I'd suggest taking them outside and using them for air-rifle targets! :D

But there does seem to be a crazy valve resurgence these days.

Tube checkers are not perfect because they test static and not dynamic performance. But they are perfectly adequate 99% of the time.
How do I know, I used them almost every day for more years then I can recall.

I also used them, not on a daily basis, as it depended if people brought valves to be tested.

But as an engineer, in a busy service department, we never used it ourselves, as it's not a particularly useful service technique.
 

Video Warrior

New Member
oh dear all kinds of valves, he has rectifiers and all sorts of radio and TV valves, some date back to the 1920's. I expect we have more pricing clout if we can say whether they work or not, he's not used any in years and some were bought new but after all these years you never know
A couple of different levels to moving them on eBay:

If you *know* which ones are NIB (actually you'd probably have to call them NOS) that is a selling point. You can just state that they are as-is/untested.

You can do a quick and dirty continuity test on the heaters. That won't give any emission data, but will definitely tell you if you have one that is NOT going work, no how, no way.

If you want to be more thorough about all this, I'd suggest first generating a list of all the different types that you have. There are quite a few resources on this here Inter Net thing for working up base diagrams from that. Enough at least that you can check the heaters.

If you wind up shipping them around the world to a buyer, I would really stress the "as-is" aspect. You've probably seen what the friendly UPS Delivery Man likes to do with that container with the FRAGILE label on it.

OTOH, if you want that "good seller" rep, you will back 'em (if you can) with an exchange if someone gets a dud.
 
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