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 Post subject: A good tube tester
PostPosted: Nov Wed 13, 2019 3:29 am 
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Joined: Nov Mon 14, 2016 2:18 am
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I am new to vacuum tube repairs and desire a good tube tester. Presently I have been working on all american 5 radios from the 50's and 60's. Any advise would be appreciated. Checking voltages gives me a good idea where my issues lie but never seem to have a known good tube to try.


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 Post subject: Re: A good tube tester
PostPosted: Nov Wed 13, 2019 3:39 am 
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Posts: 2354
Location: Columbus Ohio
covered a few times here. You know the tubes you want to test, those really just require a good shorts test and emissions will tell you if it works.
Then on up to output Mho/Mu and curve tracers.
How much you want to spend?
100-200 gets a nice Eico or Knight
200-300 a bit better, maybe Mu's
400 and up for Hickok, etc

My picks are Knight 600B or Hickok 600a. Just acquired a B&K 500, looks interesting, untouched inside, needs some work like all these old units do.
Out of all the 30-40 I've done and flipped, I kept the Knight 600B because it detects shorts that ALL the others failed to do, with a 'shorted bogey tube' I have. It never tested right in other units but did not show a short, the Knight shows it. Even the famous Hickok 539c failed.
So, it's really a matter of taste and needs, avoid the TC-50's or other under $100 generally.

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 Post subject: Re: A good tube tester
PostPosted: Nov Sat 16, 2019 2:50 am 
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Location: St. Louis, MO
If you're just starting out and can't wait, there's always the heater continuity test. One way that tubes can fail that's easy to test for with basic equipment is to check to see if their heater is burnt out. Look up the pinout for your tube, then try a continuity test with a multimeter across the heater pins. If you have tubes with a more than 2 heater pins, test from the center tap to each of the other heater pins.

As for never having known good tubes, there's always New Old Stock (NOS). Basically, NOS is stuff made decades ago that comes in the original box that looks ratty (decades of humidity does a number on cardboard), but the stuff inside has never been used. Some tubes are still being made today, believe it or not. Audiophiles love their tube amps, so the more common amplifier tubes are still being made.


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 Post subject: Re: A good tube tester
PostPosted: Nov Sat 16, 2019 3:07 am 
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Joined: Sep Tue 30, 2014 6:08 am
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Location: Norfolk, VA
Leigh said it best - and it echoed my experience:

viewtopic.php?p=2925245#p2925245

I've literally seen dozens of tubes tested on great testers (Hickok 539 and B&K 747B) that just would not work in a circuit, 6GH8A's anyone? They'd test well beyond minimums on a tube tester (and no shorts!), but just would not work in a Color Oscillator. Same with 12BE6 tubes - great on the tester, DOA in an AA5......

With AA5's subbing a tube goes further for me than testing. I just keep a few of the usual suspects on hand, despite three testers (707, TV-7D/U, and my favorite Hickok 752A).

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 Post subject: Re: A good tube tester
PostPosted: Nov Sat 16, 2019 3:13 am 
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Joined: Jan Tue 10, 2012 8:39 am
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My simple emission tester has never been wrong.


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 Post subject: Re: A good tube tester
PostPosted: Nov Sun 17, 2019 2:01 am 
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Joined: Oct Thu 04, 2018 2:11 pm
Posts: 188
Location: Suburban Chicago
Personally, I feel there is enough utility to a tube tester to have one, a Heathkit IT-3117 in my case. It is just a simple emissions and shorts tester. It is basically the same circuit as the Knight testers and a bunch of other emission testers from Eico, Conar, etc I like the model that I have because it tests compactrons and I have a pair of Heathkit radios that use compactrons. Heathkit is not the only brand that tests compactrons and not all Heathkits do so if that is potentially important to you make sure verify that the testers you are looking at will test them. There is nothing magic you just have to have the 12 pin socket for them and enough test switches. By the same token if you need to test very old four pin tubes you might want to make sure the tester you buy has sockets for them. But if it has enough test switches you can get around the lack of a socket for a particular tube. The IT-3117 does not have a seven pin socket. I don't know if I will ever need one but I happened to have a seven pin socket and there is room on this tester to drill a hole and mount it so I did. Of course you can also make adapters that will plug into some other socket and give you the sockets for tubes that a tester does not accommodate natively. That won't work for compactrons however, since you need at least 12 switches. Most testers that test them have 13 switches because they have a separate switch for the "top cap" connector needed for some tubes even though it could be connected in parallel with another switch. If you were to buy a very old tester made before 9 pin tubes became commonplace it might not test them so make sure that the tester you buy will accommodate the tubes you will want to test or can be adapted to do so with socket adapters.

Emissions testing gives you a simple test of quality. Shorts testing weeds out tubes that you should not use in any equipment, even the further tests on your tube tester! But it is certainly true that the best test of in circuit performance is to use them in the circuit they are meant for. If you get a new radio you should shorts test the tubes before powering it up. If a tube does not seem to work in the radio you can test it for emissions and that may tell you that the tube is either dead or a candidate for a less demanding application. Testing all the tubes in a newly acquired radio will flag the ones that MIGHT be a problem in the radio but it is ultimately the in circuit performance that should guide your decisions on which tubes to keep or replace. Now if you are selling tubes then by all means get a good transconductance tester like a Hickok. People just won't believe the results from anything else. I don't sell tubes so I don't need a transconductance tester but I do have a uTracer which is a modern tube tracer that is run from a PC for when I want to look at a tube's performance in detail. You don't need to to that to troubleshoot a radio but I am an electrical engineer and gadgets like that are just too tempting to resist even though I may never make much use of them.

The biggest reason to NOT get a tube tester? Some of us find them rather addicting actually so if you buy one you run the risk of adding One More Thing to the list of things that you feel driven to collect!


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 Post subject: Re: A good tube tester
PostPosted: Nov Mon 18, 2019 12:41 am 
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Joined: Aug Sat 17, 2019 5:35 pm
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[/quote]The biggest reason to NOT get a tube tester? Some of us find them rather addicting actually so if you buy one you run the risk of adding One More Thing to the list of things that you feel driven to collect![/quote]

Wise words. The engineering side of me was/is also interested in how tube testers work. I started out with a relatively inexpensive Mercury model. Now I have a 600A, TV-3B/U, TV-7D/U, a newly acquired TV-10D/U. The all use the same basic Hickok circuit, so why do I feel the need to have all four? If that wasn't enough I am currently building my own tube analyzer in order to get test results which reflect the bogey tube values specified in tube data sheets.


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 Post subject: Re: A good tube tester
PostPosted: Nov Tue 19, 2019 1:27 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8923
Location: Long Island
Quote:
I am new to vacuum tube repairs and desire a good tube tester. Presently I have been working on all american 5 radios from the 50's and 60's. Any advise would be appreciated. Checking voltages gives me a good idea where my issues lie but never seem to have a known good tube to try.


This is a question that gets asked every three weeks around here; do a search on the forum and you'll get lots of opinions. Everything from needing highly tweaked instruments touched by gurus to give magical micromho readings with far higher precision than any tubes were ever made with, to "don't waste your money."

Having owned a variety of tube testers in my time from the most basic to highly sophisticated, I can tell you from first hand experience that none of them can tell you with 100% certainty that any tube is "good," i.e. it will fully meet all of its specifications in any circuit you put it in. Oh sure, with rectifiers and audio tubes it is hard to go wrong, but at higher frequencies and power levels, tube testers get pretty far away from reality. The only valid test of a good tube is what it does in the circuit. So what are tube testers good for? The answer is, they can tell you with a very high degree of accuracy when a tube is bad! This can save you a lot of time by helping you pinpoint problems right away. If the tube is bad there's no point in looking for trouble elsewhere. Shorted or gassy tubes can damage other components in equipment, which is another reason to own a tester and use it to ensure the tubes in something are in good condition.

That being said, I think the best "bang for the buck" is in dynamic emission and proportional emission tube testers which will do a fine job of identifying dud tubes. Mutual conductance testers give you a little more information on a tube's performance, but a tube has to have good emission and no shorts in the first place, otherwise mutual conductance is irrelevant. Fortunately the dynamic emission and proportional emission units tend to be more plentiful and less costly. Names to look for include Jackson, Precision, Sylvania, B&K, Triplett, Eico, Heathkit, Knight, and others.

One thing you need to consider is the age of the tester relative to the radios you are working on. Newer tube testers often skipped older, obsolete tube numbers, while older testers didn't have the newer numbers and sometimes could not be updated. TV repair testers often focus only on TV and entertainment tubes while industrial and commercial testers often bury the popular numbers in pages and pages of obscure industrial tubes nobody uses any more. So most of us end up with two or more tube testers to handle all the different vintages and types of testers we work on.

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 Post subject: Re: A good tube tester
PostPosted: Nov Tue 19, 2019 6:10 pm 
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Joined: May Thu 04, 2017 1:08 pm
Posts: 296
Location: Raleigh, NC area
And since you are new around here...not to discount replies from Anyone Else...but when Chris108 replies, you might take note.

I'll add my 3 cents:

-- Use Google. Something like this: "tube tester recommendations site:antiqueradios.com". tubesound website also has good information.
-- A tester is worthless without Tube Data. Make sure whatever tester you decide on has a large store of data freely available, not just what might be on the roll chart.
-- There are often adapters which were sold or are available to extend the range of tubes which can be tested. So maybe you find an older tester which doesn't have sockets for the newer tubes, e.g. 9-pin or Compactron. See if adapters were sold to allow those newer tubes to be tested on the tester you are considering. Coletronics made one such adapter. Precision as well.

From my limited experience, I know that Precision 9xx-series and 10-xx-series fit the bill for "dynamic" emission (as Chris mentioned), and also have large data sets and adapters available. But they are older units and... (a) they have complicated mechanical linkages; (b) they don't test leakage well; (c) working ones might be harder to find and/or need diagnostic skills to repair; and (d) you might need to do some wooden case restoration, if you care about looks. B&K 667 isn't expensive, and has a sensitive leakage test, as do some Sencores, e.g. various flavors of Mighty Mite.

As Chris said, one tester likely won't fit all your needs. As K4DLM said (and probably others as well):

"A man with One Tube Tester knows whether or not a tube is good or bad. A man with Two or More Tube Testers is Never quite sure! "
https://www.antiqueradios.com/forums/vi ... 5&start=60

Dave


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 Post subject: Re: A good tube tester
PostPosted: Nov Wed 20, 2019 1:41 am 
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Joined: Dec Wed 26, 2018 3:46 pm
Posts: 19
Vintage Tube testers are for me very addictive, and they can turn out to be a hobby by themselves. I have 7 testers now and I don't wanna part with any of them, they all have different areas where they are at best.
For emission I use most the Funke W19 and for slope etc it's the rpm370/1 and/or ct160. Tv-7B is a fast and nice one as well. Depending on the tube I have some choices.


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 Post subject: Re: A good tube tester
PostPosted: Nov Wed 20, 2019 2:43 am 
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Joined: Jun Sat 15, 2019 7:43 pm
Posts: 267
khutch wrote:
The IT-3117 does not have a seven pin socket. I don't know if I will ever need one but I happened to have a seven pin socket and there is room on this tester to drill a hole and mount it so I did.

What seven pin socket were you missing??
Attachment:
TesterSockets.jpg
TesterSockets.jpg [ 91.5 KiB | Viewed 238 times ]


DM


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 Post subject: Re: A good tube tester
PostPosted: Nov Wed 20, 2019 3:16 am 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 802
no acorn?


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 Post subject: Re: A good tube tester
PostPosted: Nov Wed 20, 2019 4:45 am 
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Joined: Dec Sun 02, 2012 2:45 am
Posts: 28
Location: Milan, Indiana 47031
Unless you're into military or 30's amateur radio equipment you'll never miss the acorn socket.

Randy AB9GO


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 Post subject: Re: A good tube tester
PostPosted: Nov Wed 20, 2019 2:14 pm 
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Joined: Oct Thu 04, 2018 2:11 pm
Posts: 188
Location: Suburban Chicago
devilsmist wrote:
khutch wrote:
The IT-3117 does not have a seven pin socket. I don't know if I will ever need one but I happened to have a seven pin socket and there is room on this tester to drill a hole and mount it so I did.

What seven pin socket were you missing??

DM


Yes, it does have the two small 7 pin sockets on that list but they dropped the large seven pin socket with the lamp test socket. They never updated the documentation to reflect this, or at the least there's a lot of documentation out there that has this wrong. There's a blank spot on the panel where the IT-17 has that socket so it is easy enough to drill the holes and add one. In the photos below the IT-17 is first followed by the IT-3117 and it is easy to spot the missing socket. I suppose that the large 7 pin tubes were rare enough to justify saving cost by dropping the socket even though the old 4, 5, and 6 pin sockets were retained.

There are no acorn sockets on either tester. To test them or Magnavols you would have to make adapters.

I have a small pile of radios to restore, one or more may have a seven pin tube that needs that socket. If not, some future radio will.

Attachment:
It-17.jpg
It-17.jpg [ 210.17 KiB | Viewed 188 times ]


Attachments:
Heathkit IT-3117.jpg
Heathkit IT-3117.jpg [ 599.74 KiB | Viewed 188 times ]
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