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Old 15th Feb 2018, 11:42 am   #1
Don Henschel
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Default Recommendations for valve tester

I'm looking for a valve tester capable of testing valves with side terminals and one suggestion was a Taylor 45. Any idea if the Taylor could test these? Did many early British sets use these? I never saw these critters before because they were never used In Canada or United States.
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Old 15th Feb 2018, 12:33 pm   #2
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Default Re: Recommendations for valve tester

The simple answer is any valve tester you like. Just make up an adaptor using a CT socket and a plug to fit one of the bases it does have.

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Old 15th Feb 2018, 12:41 pm   #3
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Default Re: Recommendations for valve tester

The Ct8 side contact base was used for a short period here in Europe around 1938 so any tester manufactured after about 1940 is likely to have a Ct8 socket.

As to which tester, it depends on what you are testing for. If you just want to know if a valve is servicable, has good emission and no inter-electrode shorts then a Mullard high speed tester like the E7600-4 is up to the job. If you want to measure mutual conductance to match valves you will need one of the AVO characteristic meters like the CT160 or the Taylor 45C.

There are other testers available in North America that are likely to be suitable, those from Hickok or B&K for example.
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Old 15th Feb 2018, 12:49 pm   #4
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Default Re: Recommendations for valve tester

I certainly wouldn't buy a valve tester simply to test side contact valves, as they were never very common anyway. There are usually octal based direct electrical equivalents, so you just need to make up a base adaptor as has been suggested. Alternatively just test them in circuit.
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Old 15th Feb 2018, 12:59 pm   #5
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Default Re: Recommendations for valve tester

I believe that side-contact valves were originally a mainland European development, where they seemed to relish valve base/socket complexity. Possibly, the intention was to give contact reliability by the scraping action of insertion, but they actually turned out to be troublesome and didn't last very long, essentially briefly pre-WW2, and many types were subsequently rebased as International Octal.

The US, by contrast, went for simplicity in socket design and Britain, as so often with things, found itself somewhere in-between. A similar thing happened post-war with B8a ("rimlock") valves featuring in many Continental sets, also popular in Britain but shunned in North America.

Beware that these Ct8 sockets are numbered counter-clockwise when seen from below, by contrast with other valve bases. (Must have caused a bit of muttering over the years!)
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Old 15th Feb 2018, 1:37 pm   #6
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Default Re: Recommendations for valve tester

Quote:
Originally Posted by Don Henschel View Post
I'm looking for a valve tester capable of testing valves with side terminals
These bases were quite common in Germany late 1930s. As far as I can see from the photos I could find, the Taylor 45 has the right sockets on it. Any German tester from that period should be able to test them. Search on German Ebay for Röhrenprüfgerät. However that's an expensive solution. As suggested above if you only have a few valves I would just make up an adaptor. As a real kludge, get a scrap valve base that fits in a tester that you have and solder a few leads with crocodile clips on to it. Attach the valves with the crocodile clips.
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Old 15th Feb 2018, 1:51 pm   #7
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Default Re: Recommendations for valve tester

I was a bit confused at first- I expected to see a picture of valves with B4 or B5 bases with a screw terminal on the side.

The European bases in question are normally called side contact bases.
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Old 15th Feb 2018, 3:14 pm   #8
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Default Re: Recommendations for valve tester

The Tubes in picture 1 have no side contacts,
they have top contacts
and this is usualy the grid connection.

To test only some tubes,
use an old Radio-Transformer with 4 + 6.3V and a meter.

Peter
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Old 16th Feb 2018, 3:24 am   #9
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Default Re: Recommendations for valve tester

Thanks ukcol, turretslug, and bluepiolet! They are more common than realized in German sets with variations such as a smaller diameter example and they were used from what I have found out so far from 32-39 and beyond and my VE301Wn even hasten in the larger diameter version. Some of the later sets of these examples have full sets of valves with CT valves. I was bidding on a set of 20 and got Blitzkrieged at the end of the auction!! €275 was the final result and if there were Third Reich stamps on these valves I'm sure an Atombomb would have been dropped. Yes I have wanting eyes cast upon the Philco People's sets and Ekco round Bakelite but most are scared of shipping and meanwhile my fine but nicotine tar infested Philco 444 arrived very fine and dandy!! It is much easier to obtain a German set due to this and there are some very fancy ones out there as well. I have watched an opulent 527,537, and A22 drift by due to eeeeeeek international shipping! I'm waiting til the end of another set of valves from the same seller and hopefully the competiting fellow vultures like myself will have empty pockets and full bellies after feasting on the first 20 valve carcas. Oh yes and there is even a set with eye tubes as well which I most certainly will get slammed on but who knows perhaps I will get lucky.
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Old 16th Feb 2018, 6:41 am   #10
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Default Re: Recommendations for valve tester

Don,

I have already done a lot of work to be able to do what you're looking for.
To test old European tubes/valves on a cheap and common emission tester.
For that I have chosen the B&K 607 or 667. They are actually the same tester but in different casings.
An added bonus of this tester is it's ability to detect even the slightest grid-currrent, possibly the best among emission-testers.
Before starting to use the tester, go through all components and replace those outside spec's.
In mine (I have one of each tester types) I had to replace all resistors and electrolytic capacitors.
Then try to get hold of a NOS good and tested tube, like a 6L6 for calibration.

The tester should come with a setup chart. The one I have is probably the latest from B&K type 497-015-0-180.
This booklet lists very many US and European tubes but obviously none with Sidecontacts. The list contains numerous errors and those found are corrected in my list, attached.
Now go build a sidecontact-adaptor iaw instructions in my file and you're good to go.
The file also hold instructions on how to make Loctal B8G and Steel-Tube G8A to International Octal adapters besides an octal-to-octal adapter for those tubes that have filaments on pins 1 & 8.
Now the adapters wouldn't be much good if you have no settings for the B&K testers, so I did A LOT of research and testing of actual NOS samples to do a chart of so far 76 pages of settings for use with or without adapters on the 607/667 models.
The list is ever expanding and so are the numbers of adapters.
My latest work was done in November, 2017 and will continue when time's permitting.
Obviously Russian tube types are missing for starters.

Remember that these emission-testers are OK for sorting tubes in good and bad besides worn-to-a-degree. Possibly also to investigate how well matched dual-triodes are etc. They are NOT able to establish the exact state of the tube; for that you need a calibrated mutual conductance tester and they are FAR more expensive.
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Old 16th Feb 2018, 7:53 am   #11
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Default Re: Recommendations for valve tester

Just look near the bottom of that B&K chart... adaptor C is for 8-pole side-contact valves!

A basic 'emission tester' is cheap and will do a reasonable job of which valves will work in a radio/TV and which will not. It'll do a reasonable job of matching the quiescent currents of pairs of valves to be used in push-pull stages where they have to work at equal grid bias voltages. They are relatively cheap.

A mutual conductance tester adds the ability to measure the 'gain' of the valve at an adjustable grid bias voltage This makes them a little bit more certain on the 'Will it work in my radio?' question, but their added value is in slope-matching pairs that will be used in push-pull stages where there is some degree of independence in bias conditions. Many people on this forum fave built their own. Do a search for the Sussex Valve Tester. They fit whatever sockets they need.

Taylor made some good mutual conductance testers. Their last model, 45D, can be expensive, earlier ones are more affordable. AVO made some good mutual conductance testers, generally sporting a wider range of sockets than Taylor's models did. However, AVO's are VERY expensive, and their last models, the Mark IV and VCM163 are crazily expensive. As far as I can see, their tangible advantage over 'lesser' testers is that it is believed that the words 'AVO tested' and a photo to back it up will enhance the auction prices reached by valves being sold. AVOs and Taylors use AC for the electrode supplies, and this makes them VERY difficult to calibrate. The only easy check is with a calibrated valve... calibrated on a DC type test rig. Oh, be aware that all these testers are too limited in the power and current departments to test power valves at their true ratings. Their data books have them do tests at reduced current/power. This can fail to find some faults.

DC testers like the Sussex design mentioned are easy to calibrate and can therefore provide calibrated valves for calibrating Avos and Taylors. A DC tester can be used to plot a set of characteristic curves for a valve. The slope of the line is the mutual conductance and the plot shows how it changes over bias conditions.

If you want plots from a ready-made instrument, then Tektronix made curve plotters. Very expensive and you'll need an oscilloscope camera. Rare in Europe, more easily found in the US.

So there you have it.

If you want a good and accurate valve tester, you're going to have to build it. If you want a tester that impresses a lot of people and has the edge on versatility of sockets, get an AVO if you can afford it. If you're interested in weeding out valves which won't work in your radio or are getting towards the end of their useful lives, almost any tester will do. A few measurements IN the radio needs no valve tester and does the job.

David
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Old 16th Feb 2018, 10:06 am   #12
Don Henschel
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Default Re: Recommendations for valve tester

Forgot to mention every Hickok and B&K I saw on eBay.com or ca dont have these sockets and my friends into ancient tube radios hasn't either. Other than 1920's sets he has post war Pye and these are a puzzle as well. My Stark tube tester is from early 40's and my Heathkit probably late 50's or possibly early 60's. They can test peanut 7&9 pin,Octal,Loctal and my Stark I do believe can test the old 4 pin. Years ago I even had a hardware store tester where you brought your tubes to test and purchase ah the good ol days. It even tested vibrators. Anyway no doubt about it, the German sets have lots of these as indicated how hostile my competing vultures were and who knows how much higher it would have gone depending on who was circling. I'm bracing for the assortment including 3 eye tubes as well. All in that set are CT. Calibration should not be a problem due to the fact I have numerous NOS tubes some of which are WW2 military surplus. I just don't have CT-8 in my hoard-yet. If I win these I will be forced to purchase homes for them like stray cats and dogs.
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Old 16th Feb 2018, 10:54 am   #13
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Default Re: Recommendations for valve tester

Quote:
Originally Posted by Don Henschel View Post
I'm looking for a valve tester capable of testing valves with side terminals and one suggestion was a Taylor 45. Any idea if the Taylor could test these? Did many early British sets use these? I never saw these critters before because they were never used In Canada or United States.
The Taylor 45 does not have a socket for the 8-pin side contact valves - certainly not the Taylor 45D. It has ten valve bases - there was no space for any more, so adaptors were available to extend the range. I have a Taylor 45D and wished to extend the range. The original adaptors plugged into the B14 socket and plugs to fit that socket are unobtainable. As none of the valves that I wished to test had more than eight pins, I made a range of adaptors which plugged into the I.O. (International Octal) valve base. (All of the pins of the sockets on the 45D, and I guess other testers, are 'commoned' - that is pin 1 of one socket is linked to every other pin 1 and so on. Hence, to make the adaptors, it was just a matter of obtaining the desired valveholders and cross wiring them pin for pin to an Octal plug 'robbed' from scrap valves.

I covered this topic in two threads, the first in May 2014 here:

https://www.vintage-radio.net/forum/...+base+adaptors

In October 2016 I made a further two adaptors which I covered in this thread:

https://www.vintage-radio.net/forum/...+Base+Adaptors

I don't have a need for an 8-pin side contact adaptor, but I drew a wiring diagram anyway, and was going to make one some time so I've attached the diagram.

I share a fascination common with many of us, for test equipment, but if I didn't have a valve tester I wouldn't bother to buy or build one. It's a nice to have non-essential item. Easiest way to test as valve - having checked the heater is good - is by substitution. I bought my 45D about 35 years ago in pre audio-phool/pre internet days when there was even less interest in valve testers than in valves. It was an impulse buy at a radio rally. It had languished ignored all day on the bring and buy stall at £20.

I bought it as I was leaving the rally - it seemed an act of extravagance at the time, and by the standards of the day, it was. A different world now - there are lots of people of advancing years with time on their hands and high disposable incomes who trawl internet and are content to pay whatever they have to, in order to get what they want, not least for valve testers, 60s tat record players and certain guitar amplifiers. More about the joy of ownership than the utility value.

Hope that helps a bit.
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Old 16th Feb 2018, 11:08 am   #14
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Default Re: Recommendations for valve tester

Quote:
Originally Posted by Don Henschel View Post
I'm bracing for the assortment including 3 eye tubes as well.
You don't say what they are but if there's a NOS EFM11 there expect it to be expensive.
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Old 16th Feb 2018, 11:40 am   #15
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Default Re: Recommendations for valve tester

Quote:
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Quote:
Originally Posted by Don Henschel View Post
I'm bracing for the assortment including 3 eye tubes as well.
You don't say what they are but if there's a NOS EFM11 there expect it to be expensive.
There's an EM34 there which looks to be in good physical condition, typically £75 for N.O.S and progressively downwards.

About £40.00 for current production EM4 substitutes from a supplier in Spain.

I wonder if anyone actually ever bothers to buy such expensive magic eyes - invariably costing more than a set is worth, for what is - after all - a pointless gimmick unless used in test gear such as a bridge, to show a null??
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Old 16th Feb 2018, 12:43 pm   #16
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[QUOTE=David G4EBT;1017597]
Quote:
Originally Posted by bluepilot View Post
I wonder if anyone actually ever bothers to buy such expensive magic eyes - invariably costing more than a set is worth, for what is - after all - a pointless gimmick unless used in test gear such as a bridge, to show a null??
The EFM11, often used in late 30s German radios, also has a pentode section in it (as you might guess from the F). If that goes wrong then you have to buy another one, even if you don't use the magic eye bit.

As for the price, does the hobby make financial sense anyway?
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Old 16th Feb 2018, 1:28 pm   #17
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Default Re: Recommendations for valve tester

Quote:
Originally Posted by David G4EBT View Post
I wonder if anyone actually ever bothers to buy such expensive magic eyes - invariably costing more than a set is worth, for what is - after all - a pointless gimmick unless used in test gear such as a bridge, to show a null??
If you understand these things you will realise that sometimes a visual indicator can tell you what your (or the owners) ears can't, that is, the receiver is correctly tuned to the transmission.

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Old 16th Feb 2018, 2:38 pm   #18
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Default Re: Recommendations for valve tester

Hi Don or is it Hennmann Ha Ha. My Taylor 45C or the Taylor40 does have a SC8 side contact valve socket. In fact the Taylor45C has a BR4/5, BR7
T(funk), SC8, MO8, B9G, UX4, UX5, UX6, UX7,IO1 and a IO2 valve socket. Regards Brian
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Old 16th Feb 2018, 3:46 pm   #19
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If you understand these things you will realise that sometimes a visual indicator can tell you what your (or the owners) ears can't, that is, the receiver is correctly tuned to the transmission.

Lawrence.
Well given that listening to a radio is an aural experience rather than a visual one, if I couldn't discern the difference with my ears, it would be so subtle that I doubt it would concern me. It's one thing when the set was new, but if it's vintage and in need of a new magic eye costing upwards of £75, if I needed a visual indication, that would buy a half decent 'scope. In the past, I've had a Heathkit and a Taylor bridge, both of which used EM40 magic eyes which were excellent null indicators, but given that EM40s didn't enjoy a long life and are becoming rare and costly, anything that uses them is a bit of a non-starter for me.

I think that if a signal strength indicator was considered desirable, an 'S' meter would be a better bet, which is why - in the 50s & 60s when R1155s were heavily modded by SWLs and amateurs, the eye was invariably removed along with the DF equipment, and replaced with an 'S' meter.

My recent experiences with magic eyes - pretty as they are when they still have emission - have done nothing to dispel my view that they were a short-lived gimmick. In the case of a Pye 'Fenman 1' the eye was unresponsive whether a station was on tune at good signal strength (audibly) or off tune. Initially I'd thought the eye might be on its way out, and as it used a cheap and plentiful EM80, I replaced it to no avail. However, only when an external aerial was plugged in did the AVC voltage go sufficiently negative to cause the eye display to change. A useful learning experience for me. I even built a little tester to check the original eye, which worked fine.

Same thing with a Unitra 'Figaro Special', which has a built-in Ferrite rod aerial. It uses a DM70 'exclamation mark' magic eye. (Quite long lived and cheap to replace). They eye was a dud anyway so I bought an NOS one. Just as with the 'Fenman1', even when signals were strong enough to require the volume to be turned down, the eye gave little indication, whether on or off tune. Same issue - not enough negative voltage swing on the AVC. Plugged in an external aerial, and on strong signals the eye was very responsive.

Without an external aerial, off tune, the voltage on the grid of the DM70 was -0.45V, and on tune, was -0.75V. However, just a few metres of wire plugged into the aerial socket greatly enhanced signal strength. When on tune, the grid voltage of the DM70 then varied from -4.0V to -9.0V and the display responded accordingly.
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Old 16th Feb 2018, 8:50 pm   #20
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Default Re: Recommendations for valve tester

David, its a tuning indicator, with a receiver that uses AGC you can "tune in" a station but you can't always tell if it's tuned on frequency because of the effect that the AGC has on the volume, it's well documented.....

Your ears won't easily tell you that it's not on frequency no more than they would easily tell you when trying to peak an IF transformer with a strong signal applied in a receiver that uses AGC.

Its purpose is to provide a visual indication of the tuning peak when AGC is applied, eg: stronger signals only.

I would say that the fact that the tuning indicator valve survived (maybe not in emission!) from the uptake of the Superhet in the 1930's through to the general demise of the valve Superhet design in the 1960's doing the job it was designed to do is quite a good record for a "pointless gimmick"

Anyways, drifting a bit off topic now.

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