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Old 5th Sep 2018, 11:30 pm   #1
Chris55000
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Default Valve Tester Prices?

Hi!

I've been put off wanting to get a valve tester of any type by the absolutely horrendous prices being asked for by sellers of these instruments – well into four figures!

What has sent prices to such stratospheric levels? How much would it cost in materials to make something like a "Mullard One–Arm Bandit" with more modern (possibly automatic) switching arrangements for instance? – or is it even technically feasible?

Would it be cheaper in the long run to try and build a "Sussex?"

I'm wondering if i would really need a valve tester for the 545A Tek and half–a–dozen valved Heathkits I have, or am I far better going by C.A. Quarrington's principle that valves are far better tested in the actual circuits they're employed in?

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Old 5th Sep 2018, 11:47 pm   #2
Craig Sawyers
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Default Re: Valve Tester Prices?

Sussex or uTracer. In a heartbeat.

Horrendous prices for *conventional* valve testers is from rarity this side of the pond, and most going into landfill in the decades that valves were seen as obsolete technology. One guy I know consigned ten VCM163's to the dump around 15-20 years ago as worthless - which is fifteen grand's worth now.

Tube testers in the US apparently go for a few tens of dollars at swapmeets. Much bigger country, and more survived.

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Old 6th Sep 2018, 12:10 am   #3
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Default Re: Valve Tester Prices?

Prices may be high, but I think they peaked a while ago.

I'm curious, though, about how many man-hours it takes to build and commission a Sussex?

B
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Old 6th Sep 2018, 12:47 am   #4
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Default Re: Valve Tester Prices?

A quick look on Ebay's U.S. site shows many working "tube testers" for under $200 with typical shipping costs to the U.K. between $35 and $60. Well worth it, even taking customs charges into account. Of course a 240v to 110v step down transformer would be needed.
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Old 6th Sep 2018, 12:58 am   #5
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Default Re: Valve Tester Prices?

I agree, I think the bottom has fallen out of the valve tester market and about time too!

You don't need a valve tester unless you're a valve dealer and need to provide test parameters for the valves you're selling.

The Mullard one arm bandit type with the CRT are pointless for any technical purpose and were only ever any use to have on the service shop counter to give a good bad/test result to customers who brought their valves into the shop for testing and possible replacement. I was given two of these a few years ago and scrapped them both when I moved house in 1999. Silly me, I didn't think they were worth anything to anyone, they certainly weren't to me, hundreds of cards and never the one you really needed, and then no meaningful readout, unlike a 'proper' tester.

So I think they're a 'nice to have' vintage item, and that even includes the old Mullard, but not a necessity, in my opinion, anyway.
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Old 6th Sep 2018, 4:50 am   #6
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Default Re: Valve Tester Prices?

I have, I think, 4 valve testers -- a Mullard HSVT, an AVO VCM4, a Taylor something-or-other and a Radio Shack emissions tester (from the States). I rarely use any of them. I agree that the best test of a valve is the circuit it's used in. So I check the getter hasn't gone white, check the heater is not open-circuit (with a multimeter) then check the electrode voltages in the circuit the valve is used in and work from there.

As others have said, they're nice pieces of vintage technology (I like the punched card 'reader' and the resistor DACs of the Mullard) but I certainly don't need one to do repairs.
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Old 6th Sep 2018, 7:01 am   #7
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Default Re: Valve Tester Prices?

As said, there aren't many around and the number keeps decreasing due to their fragility.

This wouldn't of itself force high prices, but it has been matched by a high demand. The demand has come initially from guitarists and 'high-end' audio aficionados. Both factions are strongly wedded to valve-based audio amplification and around their needs there has grown a small industry supplying valves, preferably NOS ones. Valve testers for matching pairs and for measuring performance figures to be trumpeted on sales websites are an important tool for valve dealers. There is a pecking order of how much different makes and models of tester whomp up the prices of valves they have tested.

Inevitably, some valve users want testers, so they can A) save money by acquiring old valves at radio rally junk stalls, from old equipment, and testing themselves. and B) some of them are untrusting of the expensive valves they're buying from dealer's web sites and auction sites, so they want to be able to check they received just what they paid for. An unfortunate side effect is that this has put a number of testers into the hands of people who don't understand (yet) that they can be destroyed by unsympathetic operation of their controls and this has reduced the tester population still further.

A commercial repairer of audio gear whether for hifi or guitar, needs to have a tester well up the pecking order on display in order to look credible.

Lost in all this money washing around the guitar and 'high end' businesses are a few people who would like to collect valve testers as interesting artefacts in their own right and a few people who would like one to help in fixing old radios. However, these people also know that you can do very well without one. If you want a valve to work in a particular circuit, a few quick measurements with it in that circuit will do the job. Where a valve tester comes into its own for a restorer is in matching pairs for push-pull output stages for those designs which don't permit separate bias setting. That said, the usual testers only test valves at low powers, and can't take the more powerful types to check matching much above quiescent conditions.

Guitarists want a lot of valves because they drive them very hard and quickly damage them.

'High end' people want a lot of valves so they can sit around plugging different ones in and savouring their different 'sonic' performances, invite a friend or two around and have something like a wine-tasting.

Advice:

If you just want to fix radios, either continue without or else build yourself a Sussex or a microtracer. The Sussex is a VERY good design, far better than the AVOs, but it will have zero street cred for womphing-up auction prices.

The Sussex, by running valves in DC bias conditions can have its calibration checked quite easily by using any calibrated multimeter.

Calibrating an AVO or Taylor VCM is a major undertaking and is usually checked by measuring a standard valve which was measured on (wait for it!) A DC test rig

It is an interesting observation that none of the people forking out huge dollops of cash for cult valves want to see a calibration certificate for the tester used to prove the goods.

I sometimes wonder hop different the world would be if valves hadn't been made with easy to use plug bases. We've learned that valves usually outlast capacitors... There must be an anthropology PhD in there, somewhere.

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Old 6th Sep 2018, 7:52 am   #8
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Default Re: Valve Tester Prices?

I wouldn't be without my Mullard mk3 (4?) Valve tester. Yes, it's a relatively 'simple' tester that gives an equally simple but very useable good/bad/so-so diagnosis. You have to remember that every person wanting a valve tester has a different remit! It is therefore simply not possible for anyone to 'tell' another what type or model VT they need. We each need to assess our needs and buy/not buy as the case may be. In my case, I just want to know if a valve is working within its spec; a good valve. Others, perhaps dealers, may want to ascertain actual parameters for publication purposes. Others may be prepared to forego versatility for portability, and so on. On a side note, I don't get this testing a valve in circuit because there could be problems with the circuit itself, that's (to me) the whole point of extracting the valve and testing it in isolation as part of structured process of elimination test/repair procedure. Valve testers; no 'one size' fits all. Assess your needs.
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Old 6th Sep 2018, 8:52 am   #9
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Default Re: Valve Tester Prices?

I seem to use my Mk3 AVO fairly frequently. Which I got for nothing at all from a friend as not working. Fairly quickly worked out the grid voltage pot was open circuit, and (unlike a CT160) was a regular linear wirewound. So was easily resurrected.

I've also got a Mk2, again free, but with an O/C meter, so essentially dud without a shed load of work. I'm going to repurpose that into a valve curve tracer using a kit of bits from a guy on Tekscopes.

I also have a CT160, which cost £100 with a known dud meter. But then I spotted a physically identical meter in a high current AVO which I got free. Wrong current, but easily sorted out with a tiny transformer and simple power supply and an op-amp. Swapped scales over and that is completely restored, functional, calibrated and re-sprayed case.

Oh, and a Taylor 45C.

And 80% of the way through a uTracer, cunningly configured so I can use AVO 163 set up charts.

That is not counting the Tektronix 575/175, 575mod122C, 577, 576 (free), and 7CT1N transistor curve tracers.

But if I didn't have this thing with valve testers and curve tracers, and wanted a single piece of kit to characterise valves - Sussex or uTracer.

Pass the medication, would you?

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Old 6th Sep 2018, 9:20 am   #10
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Default Re: Valve Tester Prices?

Quote:
Originally Posted by Bazz4CQJ View Post
I'm curious, though, about how many man-hours it takes to build and commission a Sussex?
B
It rather depends on the level of skills in not just building the circuit boards but also the metalwork. Remember this is a 'one off' for each person and not a production line timed job.
Cost can vary according to what you buy and where from. I added extra relays into mine to switch the heater voltages as the standard type switches are only rated for about 150ma. This added a little to the cost and time. I also bought a relatively expensive case and spent a lot of time getting the layout to fit the case. I'm guessing but think in my build it was probably about 25-30 hours plus whatever time I spent on the computer making the drawings for the front panel markings which I did over several weeks when I had a spare moment.
Provided that it is built correctly then commissioning shouldn't take more than about 1 hour. Excellent tester and uses the AVO book settings. There are pictures in the 'Sussex' thread.
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Old 6th Sep 2018, 11:46 am   #11
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Default Re: Valve Tester Prices?

Chris, with your background, you would be the ideal guy to build a valve tester. Internet Wheeler-Dealer prices for AVO's, decent Hickoks, and so on are horrendous.
A number of folk advocate a Sussex, Martin over in Sweden has built an ultra modern RoeTest, old vintage me just built a pure DC tester out of surplus vintage but decent items of test equipment from yesteryear((see LeyMarcAvo thread posts). You could try & get your hands on a Tek570, but then your into the realms of big money again. I did, a number of years back buy, on separate occasions, a couple of CT160's from Gerry Horrox at Crowthorne. But that was before prices rocketed, and I got good deals off Gerry as the 160's were in need of some TLC. But then, way back in the mid 60's, I had started to service & repair them at RAF Cosford(not a million miles from Walsall). Otherwise, "doing up" an AVO VCM or CT160, needs folk to tread carefully.

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Old 6th Sep 2018, 1:37 pm   #12
Craig Sawyers
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Default Re: Valve Tester Prices?

I got my CT160 from Gerry too.

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Old 6th Sep 2018, 4:05 pm   #13
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Default Re: Valve Tester Prices?

Quote:
Originally Posted by Radio Wrangler View Post
Calibrating an AVO or Taylor VCM is a major undertaking and is usually checked by measuring a standard valve which was measured on (wait for it!) A DC test rig
Well, something that's worth pointing out here is that the VCM163 is useable as a DC test rig (not sure about the other AVO's, which I've never used). With the 163, you can put a valve in, and just use the Grid Voltage to set Vg and read off Ia over 4 or 5 points, and put that data in to Excel and get Gm. I'm pleased to say that every time I've done this, and then compared that 'DC value' with what the 163 is showing separately on the Gm meter from its 14kHz AC system, the two values are within a gnat's do-dah's of each other.

Of course, I was given my 163 by a grateful client (HMG). It's pretty unthinkable that I would ever have bought one.

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Old 6th Sep 2018, 5:04 pm   #14
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Default Re: Valve Tester Prices?

Right enough Bazz, the 163 is the pinnacle of VCM ownership, & superbly made. I've never worked on or owned one, but Pamphonica & other Forum folk have told me that they are just great.
Just over a year ago, on 1st Aug., I started a "Standardised Valve" Thread and freely provided quite a few DC graphed pentodes to Forum folk. Many folk responded with their Ia/Vg tabulations &/or plotted graphs, then passed the valves to others, & so on. Many folk's VCM's attained pretty close curves to my DC ones, and some of us got reasonably close to Martin's 21st century ultra-modern DC RoeTest Tester. So AVO, even with their AC method, got their designs right. Trouble is their setting-up/calibration procedures. A lot of folk just cant get their head around the thoughts of P - P, RMS, root2, waveform pulses, & so on. As, in real life(i.e. their valves only work under DC conditions when in folks vintage radios & equipment), their valves work differently. Hence myself & others have been trying to persuade folk to build DC testers, if you're really into valve testing in a big way. Its not rocket science.

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Old 6th Sep 2018, 5:41 pm   #15
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Default Re: Valve Tester Prices?

Reading this is there more than a touch of jelousy here?

What the Avo gives is a fast and effective method of connecting voltages to pins. A bank of ordinary rotary switches does the same job, but the side by side arrangement allows the eye to scan the switches to discover that the heater really has been connected to the anode. A cheap tester blowing valves up quickly becomes an expensive tester.

I quite agree that a DC tester is probably better, but several stabilised and current limited power supplies are not exactly cheap. A 450V at 200mA, to fully test a valve as is wanted, is quite some beast. I have been looking at stacking several Roband PSUs to get this facility, and the Robands are 2 a penny. I have stacked them to determine if the current limiting does work over multiple PSUs, answer, yes.

If I could bear it, stripping the switches from an Avo to use with the DC PSUs would be good. Snag is, will the Avo switches work reliably with DC, not AC?
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Old 6th Sep 2018, 8:38 pm   #16
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Default Re: Valve Tester Prices?

Most of the people on here with valve testers got them well before prices went silly. I had an AVO MKII which I think cost a tenner from Jim Fish in the 60's, and I bought a Taylor 45D for £20 at a radio rally bring and buy stall, so you can estimate how long ago that was.

It rarely gets used fixing things. Occasionally, it gets used to check boxes of gash valves for other people. It does all that's asked of it.

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Old 6th Sep 2018, 8:53 pm   #17
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Right enough Woodchips, one of the essential parts of a homebrew DC tester is a good HT source. In mine, the LeyMarcAvo, the "Ley" is short for LEYBOLD. A German manufactured DC HT PSU from the 60's/70's. I fitted the gubbins from two - to supply Anode & Screen volts separately. Its managed to test & graph EL37's up to 117mA at the AVO VDM's recommendation of 250V for anode & screen. As for AVO's great thumbwheel switch assembly - I've used the complete valve holder panel from an AVO VCM Mk2. The Mk2 had been severely got-at before I acquired it, but it made a great donor. For HT's of 400V and above - I built a separate HT PSU, capable of 600V & is red-lined at 200mA - - from the Mk2's mains HT transformer with its 18 sec tappings originally for anode & screen volts. All the gumph about these is in "Search" from a few years back. I've also tested & graphed an STC4212D & one or two other big thumpers of valves.
I think the Mk2 cost me £100, and all the other donor bits of T/Eq(including a Marconi TF1041C Valve Voltmeter) I think came to between 50 & a hundred quid.
So Chris, with his T/Eq expertise, is an ideal chap to have a go. And there are other Forum/BVWS folk out there who have built decent DC testers cheaply.

Regards, David
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Old 6th Sep 2018, 9:11 pm   #18
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Default Re: Valve Tester Prices?

I've never personally or professionally owned a valve-tester: for me there are two situations:

[1] Valve in the equipment it's intended to operate in: does it do what the spec says it does? Static DC measurements, along with shoving a signal in and seeing what anode-current it can produce.

[2] Valve used in-service: I send it back to EIMAC and ask them to give me a service-report [yes they still do this]. That's good enough to satisfy professional/military clients.

The big issue I see with most 'technician'-type valve-testers is that they generally can't get near driving a 'power' valve to anywhere near its specified emission: for example to emission-test something like a GZ34 rectifier your tester needs to be able to deliver in excess of 700mA *per anode* and for relatively-humble AF/RF/line-output valves over an amp needs to be able to flow if the emission's up to scratch.

Something like a PL519 is specified to have enough cathode-emission to handle 1.4 Amps peak! Show me a 'technician' valve-tester that can confirm this, and I'll buy it.
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Old 6th Sep 2018, 10:45 pm   #19
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Default Re: Valve Tester Prices?

Valve manufacturers need to run their products right up to their full ratings to verify that nothing is amiss. Nothing flashes over at full voltage, and the cathode really can do full current on all they ship. Samples of their valves got accelerated life tests, run flat out until they failed. This was necessary for quality control. The reliability of the better makes didn't just happen by accident.

So you'd have a hard time trying to spot many of the familiar instruments in the footage of Mullard's Blackburn factory that's appeared on the web.

They do a useful job as a check of low power operation, but the serious players had to use custom-made test panels.

David
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Old 6th Sep 2018, 11:14 pm   #20
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Default Re: Valve Tester Prices?

In #9, Craig, you refer to a guy on Tekscopes. Is his circuit available freely? Last year I knocked up a little adapter box (B9G socket, heater transformer) with interconnect leads to allow testing of ECC8x(x) triodes on my TQ 71 transistor curve tracer. A family of curves, simplified to just two lines giving an almost instant gm value (and DC conditions for the cognescenti). Maybe I could use his circuit with my CT71. Obviously to go beyond triodes, I would need a PSU for screen grid supply.
I had a 575 myself 30 years ago. It cost me £10, plus another £10 for the big IC adapter attachment. When I was selling up prior to moving, Carsons offered me £1700, the best deal I ever did. I usually LOSE that much on a deal.
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