Testing Valves

[Eldridge]

Hi All,
I've inherited a large number of valves some are NOS but many have been used and all have been stored for 30+ years.
They are mainly common radio and television valves with a few odd ones.

Some have the markings rubbed off so any tips on identifying them would also be useful.

I'd like to move them on, but would not want to sell them on Ebay untested, as this only causes problems.
can any one suggest a good valve tester or a method of testing them.

Many thanks.

[Station X]

Unless you've got loads of sought after audio valves like PX4's you won't make enough profit to cover the cost of a tester. Apart from that, testing valves is a long slow business.

Sorry, but that's how it is.

[Wellington]

Others have made similar enquiries, Eldridge. I just put the word 'tester' in the forum search box and a few old threads came up which may interest you. For example…

For the ones that have lost their markings, you can often work out which element within the valve is connected to which pin, and then work out the pinout. Again, the forum search function is your friend, here

[frankmcvey]

Hi, Eldridge, and welcome.

I've passed your message on to a knowledgeable friend with a valve tester in your area.

Failing that, I have a couple of serviceable valve testers that I intend to sell on Ebay and would be happy to give you first refusal; very heavy kit, though and I wouldn't entrust it to a courier, so it would be quite a distance to collect.

Cheers,

Frank

[Diabolical Artificer]

To ID unmarked valves you need to have some knowledge of the sort after types for example ECC/12A types which are twin triodes on a B9 base, you can see the two anodes clearly. A good place to start is here - http://www.r-type.org/inx/main-inx.htm

If you're just after the money you'd be better selling them onto a dealer in one go after having ID'd as many as you can to get a rough idea of worth, as mentioned testing takes hours & valve testers require knowledge to use them, lastly a lot of valve stashes are full of worthless ( in money that is) valves; out of 100 valves your likely to find less than 5 that are worth anything. Do the maths, EG a valve takes at least 5 minutes to test, 5 x 100 = over 8 hours of testing for 5 valves worth £100 say at best, so £12 an hour roughly, 10 minutes to put on ebay (more like 20), take off fee's, time it takes to post valve etc .... you get the picture. Valves worth looking for NOS GEC KT88's, PX4's, Mullard long plate ECC83's and Brimar 5U4G's to name a few.

If you have a good few ECC/EL types as mentioned, try contacting Phil at Langrex, good luck, Andy.

[David Simpson]

Hello Eldridge, welcome to the Forum. Your issue has been covered extensively in recent months. Might take a bit of getting used to, but look up the "Search" facility in the top blue bar, third from the right.
A hoard of valves, sometimes seemingly NOS, are usually just that - a "hoard" gathered by a hoarder. Many "hoarders" - old boys from a past generation, replaced duff valves in radios, but popped the duff valves into the pristine new box - then left them under the bench "just in case".
Valve collecting & testing folk sometimes get big dusty/damp cardboard boxes, full of valves of all ages & conditions, dumped upon them (myself included). Our eyes might brighten at the site of a PX25 or a KT88, but mostly we're disappointed - they're phooked!
If you haven't got a decent valve tester, for Gods sake don't dash out & buy one, that subject is also a minefield (check "Search").
Best advice - find a friendly & helpful Forum guy near you with a decent valve tester, and ask him to kindly help. I've been persuaded in the past by the promise of a coffee & an open packet of Hobnobs, and a wee box of Ferrero Rocher chocolates afterwards if I discover something decent.
Going to a "known" internet or saleroom wheeler/dealer might put you at a disadvantage over the worth of the "hoard".

Regards, David

[Eldridge]

Thank you all, I have over 300 valves so that will take some time to test and probably goes beyond even what an enthusiastic friend might consider reasonable even for a Ferrero Rocher. I'm an electronics engineer by trade so know the hot end of the soldering iron from the cold one, but valves are before my time. A valve tester seems like the way to go and probably never lose value if looked after. Seems like I need to get to know my test equipment.

Many thanks for the inputs so far.

[David Simpson]

I'd still advise against splashing out on a valve tester, especially if you've only got 300 valves or so. Even if they all sort of worked, they might only be worth £1 each. However, a decent working & calibrated VT such as an AVO CT160 or MK3 would cost nigh on £600, or sometimes a lot more, at least these days. Then, as many a recent thread post will tell you, they're all over 60 years old & can cost a fortune to repair if they go wrong. Other British VT's like the Mullard & Taylor are still well thought of, but still cost a few hundred quid for a decent one.
Also, some " hoards" are just ex 1950's/60's TV valves, mostly of little value.
Going by Forum folk's locations, and the BVWS membership list, there must be heaps of vintage radio enthusiasts near you. Some with decent valve testers & a friendly nature.
If you feel a desperate need to acquire a valve tester - keep well away from internet sites & dealers - there are one or two highly respected Forum &/or BVWS members who can be recommended.
Modern electronics experience wont prepare you for the weird application of RMS/P to P physics involved with just about all British & American 20th century valve testers.

Regards, David

[Catkins]

Originally Posted by Eldridge

A valve tester seems like the way to go and probably never lose value if looked after. Seems like I need to get to know my test equipment.

Some people sell on "filament continuity tested only". This isn't as good obviously as emissions tested, but, it is better than nothing, and all it takes is a multimeter. If you look-up the valve pin-out you can also do inter-electrode shortage tests with a multimeter too.

The older two panel AVO valve tester (as opposed to the later more sophisticated AVO Valve Characteristic Meters MK I-V) is often a lot cheaper, and for many valves (especially pre-50s), it still gives good results.

[GrimJosef]

Originally Posted by David Simpson

I'd still advise against splashing out on a valve tester, especially if you've only got 300 valves or so ...

I'd second this. The critical thing is to sort the hoard into two heaps - one containing valves which, if they work properly, would be worth more than £3 each and the other for those which, even if they are still in their boxes and test like new, aren't worth £3. The valves in the second heap really aren't worth testing. Tot up the potential value the first heap, multiply by a guessed number (less than one) to reflect their actual condition (which may not be 'working properly') and base your decision about testing on that.

If it's any help this is the voice of experience speaking. I once came by a collection of 2,000 odd valves. There were some Mullard EL34s in there. But there were lots and lots and lots of EF91s. I got a friend to test the EL34s for me.

Cheers,

GJ

[FIXITNOW]

A quick check online will show hundreds off versions for sale at 99p and no bids !! Sort out by markings where you can then check to see selling prices online or ask here but chances are 90%+ will be in the 99p park the rest may be worth getting tested.