Tube Testers?

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   I am just getting into tube, AKA valve,  stuff. At this point I am
learning about them, how they work, how they are used, etc.  I
surprised myself a little when I identified an audio amp just by
looking at it. This amp was a component for a larger radio and did not
have any type controls on it. And no labels or anything either. It was
just a chassis with screw terminals.  
   Anyway, time to get to the point. How valuable is a tube tester for
someone who is only, or mainly,  going to be messing with audio gear
and the gear for testing audio gear. Maybe what I really need is a
gear tester? Ahem.  So, this would just be for hobby use, at least for
now,  and I am not gonna spend a lot of money on it.  Can a simple
tube tester be of much use? I say simple because I imagine a not so
simple tester will have a not so low price.
   I suppose I could always get a more sophisticated tester that needs
repair but then I would need to learn how to repair it and calibrate
it. Are they hard to calibrate? What sorts of test equipment would be
needed to calibrate one?
   I'm a machinist and I know how I would approach this type of
problem if it was a mechanical assembly. I have built pretty
sophisticated and accurate inspection equipment using less
sophisticated machines and tools. But I would be lost trying to repair
a tube tester without help.
Thanks,
Eric

Re: Tube Testers?
On 2019/10/11 5:37 p.m., snipped-for-privacy@whidbey.com wrote:
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Well, having easily half a dozen tube testers in my shop may suggest  
that I am biased, but really, how can you NOT have a tube tester if you  
are using tube equipment? Short of having only a few tube devices, and  
knowing what the parameters should be for each tube in those circuits if  
working properly (resistors good too!) so that you could use a volt  
meter only, a tube tester can take a lot of the guesswork out.

Mutual conductance testing is ideal (and most expensive type of tester)  
and the drug-store go/no go testers are at the bottom. The decision is  
driven by your budget and how often you are likely to need the thing.

If you are frustrated when trying to fix an amp or radio because you  
don't' know if the tube(s) are the cause, then you need to spend the money.

Tube testers are quite robust, so they rarely need service. Usually just  
a switch or tube test socket goes bad so pretty easy to deal with.

Get schematics for whatever tester you choose!

Oh, and get a scope at the same time. And a signal generator. And a cap  
tester...

John :-#)#
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                      John's Jukes Ltd.
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Re: Tube Testers?
wrote:

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I already have a Tek 465B and a BK 4MHz function generator. No cap
tester yet.
Eric

Re: Tube Testers?
On 2019/10/12 10:35 a.m., snipped-for-privacy@whidbey.com wrote:
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If you can find an old EICO or Heathkit component tester  
(Resistors/Caps/Inductors - using a Wheatstone Bridge) with the "Magic  
Eye". They are great for reforming caps (they go up to 600V if I am not  
mistaken) and the Magic Eye is a nice touch.

John :-#)#



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                      John's Jukes Ltd.
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Re: Tube Testers?
snipped-for-privacy@whidbey.com says...
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You may want to look into getting one of the roughly $ 20 component  
testers from China.  They do a good job of testing many solid state  
devices, inductors, capacitors and resistors.  Plenty of them on ebay.


Re: Tube Testers?
On Saturday, 12 October 2019 19:30:38 UTC+1, Ralph Mowery  wrote:
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Very handy little things. No reforming function as yet. You never know it might appear one day, but I'm not optimistic. And the one I have can't do in-circuit testing, nor C versus V info. But it does give C, ESR & loss with a single button press.


NT

Re: Tube Testers?
On Saturday, October 12, 2019 at 3:45:58 PM UTC-4, snipped-for-privacy@gmail.com wrote:
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Won't be easy to reform caps without a wee bit more voltage than a 9V battery can supply.  Besides, if a cap needs reforming, it's best to not use it.


You never know it might appear one day, but I'm not optimistic. And the one I have can't do in-circuit testing, nor C versus V info. But it does give C, ESR & loss with a single button press.
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I bought one because I couldn't resist it for the price, but I find it wildly inaccurate for low value resistance and low value capacitors.   I found a calibration procedure on-line that uses a small value cap for a reference, but it only made it worse.

Does identify terminals in transistors accurately though.  


Re: Tube Testers?
On Sunday, 13 October 2019 01:19:38 UTC+1, John-Del  wrote:
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a non-challenge to step it up onboard.

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No-one would accuse them of being quality items, but very handy nonetheless. I hear there is a new version now & then with ever more functionality.


NT

Re: Tube Testers?
snipped-for-privacy@gmail.com says...
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What is interisting is a company called Peak makes several versions for  
around $ 100.  The cheat people that are not informed.  One device only  
tests the solid state devices and the other tests restiors, capacitors  
and inductors.  That way you are forced to buy two of the units.

They are practically the same as the all in one $ 20  device in a fancy  
case.

They are not lab quality instruments but for $ 20 they work very well at  
the hobby grade.

As far as forming capacitors, if the capacitor is over 20 years old and  
there is any doubt, just replace it.  I have read that new capacitors  
are formed at the factory at a slightly higher voltage because they will  
deterioate just sitting on the shelf.  Those may be worth while bringing  
the voltage up slow on if they have been on the shelf for a long period  
of time

Re: Tube Testers?
On Sunday, 13 October 2019 19:23:59 UTC+1, Ralph Mowery  wrote:
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t wildly inaccurate for low value resistance and low value capacitors.   I  
found a calibration procedure on-line that uses a small value cap for a ref
erence, but it only made it worse.
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less. I hear there is a new version now & then with ever more functionality
.
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A lot of people have that approach. Whether replacing sound historic caps w
ith new ones that likely won't last is a good plan is debated.


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same happens to old caps. Doesn't mean they're dud.


NT

Re: Tube Testers?
On 10/13/19 3:39 PM, snipped-for-privacy@gmail.com wrote:
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And still, you persist in this stupidity.
Quality electrolytics these days are quite reliable and long
lived. Unless you're buying cheap counterfeits from China.

I've been repairing (which includes blanket recaps) for the
past 25 years now, I have yet to have a customer bring back a
radio because a cap failed.

Which is exactly why I do what I do.



--  
"I am a river to my people."
Jeff-1.0
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Re: Tube Testers?
On Sunday, 13 October 2019 22:36:21 UTC+1, Fox's Mercantile  wrote:
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That's one side of the recap all or not debate, and of course new caps don't fail in short order. The OP is free to find out why some of us don't do that. I tire of your stupidity.


NT

Re: Tube Testers?
On 10/13/19 6:08 PM, snipped-for-privacy@gmail.com wrote:
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Bwahahaha, I could have sworn you kill filed me dear.
Obviously you lied about that too.

Let's see how you talk your way out of this.


--  
"I am a river to my people."
Jeff-1.0
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Re: Tube Testers?
On 10/13/19 6:08 PM, snipped-for-privacy@gmail.com wrote:
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The answer is obvious.
You're hack.
Too lazy to do a job correctly and you find infinite ways
to justify your position.

--  
"I am a river to my people."
Jeff-1.0
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Re: Tube Testers?
On Sun, 13 Oct 2019 13:39:57 -0700, tabbypurr wrote:

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Absolutely. I've just tested some big old electros that are well over 40  
years old and they're all *totally* fine by any measure. Good, high  
quality manufacturers of the day and built to last. I would not want to  
take a chance on replacing them with new stuff that could be fake from  
the far East. In fact I don't even trust new electros from formerly  
respected manufacturers if they've turned production over to places like  
China.



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Re: Tube Testers?
snipped-for-privacy@whidbey.com wrote:

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** IME - no use at all.  

In 50+ years of working with valve gear, I have never used one and know no-ne here in Sydney who does.  

What you NEED is a supply of known good valves to use as substitutes.  

The item itself is your "tube tester" and a far better one that anything you can buy - cos it operates the valves under *actual service conditions*.  

Others here will say differently, cos they own one of more of the stupid things and *love* them irrationally, like pets.  

FYI:

Not long ago, I designed a special power valve tester that, along with a few common bench items, allows operation of audio power valves under realistic and even more severe conditions with *everything* adjustable.  

It can both sort out tubes with ANY kind of fault and match sets under conditions as found in commercial amplifiers as well.  

Nothing on the market like it exists, anywhere.  

Cos me SFA to make too.  

https://sound-au.com/project165.htm


....  Phil  





.....  Phil  



Re: Tube Testers?
On 10/11/19 8:28 PM, Phil Allison wrote:
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I have a few, but usually just to satisfy my curiosity.

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An excellent bit of kit sir.

--  
"I am a river to my people."
Jeff-1.0
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Re: Tube Testers?
Fox's Mercantile wrote:

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 Phil Allison wrote:
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 ** Nice of you to say so.
  
FYI:

My colleague Rod took a few liberties when he edited my submitted article.

He added extra circuits of his own, that he had merely simulated and did not build - he has never seen the prototype shown in the pic that I use here.

Mine is very simple, it uses only external PSUs - the 6.3V comes from a variable 5A DC bench supply and negative bias from another 2A one.

There is no "test" button as there is an on/off switch on the front of my 240/240 isolation tranny.

The only known trap is if you hastily hot switch from from pentode back to triode mode - as the latter requires way more negative grid bias. Normally just pops the fuse.

I soon found that most 6BQ5s could be pushed way more than usually seen in pentode mode - with plate and screen voltages of up to 640V and 320V respectively.  

So I built a simple output stage that employed a push-pull pair that way and got a remarkable 60W rms of clean power with no sign of red plating !!

Having long ago gone through all my junk box valves, the tester is mainly used for brand new ones, soon as I get them, in case I find a dud or one well out of match. I have even had one or two with the glass broken !!  

If I need to return a bad valve, there is way less hassle if I do so the same or next day.  

I also added a banana socket to the rear of the box allowing a short top cap lead to be fitted for types like the 6CM5 and 6DQ6B. A few Aussie made guitar amps from the 1960s used them.



....   Phil  

Re: Tube Testers?
  snipped-for-privacy@whidbey.com wrote:

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If you will be repairing anything with vacuum tubes, then you need a  
tube tester.  I suggest a mutual conductance tester.  Mine is a Jackson  
model 648.  It has a built-in scroll of setting information for many  
older tubes.

You will occasionally find these on E-Bay or at a Hamfest.

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I don't think they are that complicated.  Just a simple circuit with a  
BUNCH of switches and tube sockets wired together.  The meter is marked  
in percent, so you can see how relatively good your tube is.

At some Hamfests, I've seen "calibration tubes" that you could use to  
check your 100 percent adjustment.  I never worried about mine, since I  
just want to know if a tube is relatively good.  Suppose it is only  
reading 75 percent.  That is still a useable tube if you don't have a  
replacement.

Fred

Re: Tube Testers?
snipped-for-privacy@whidbey.com says...
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The tube tester is not of very much use, especially to someone that is  
not in the repair business.  For those that are, they will usually have  
a stock of new tubes and it is quicker to just pop one in to see if it  
solves the problem.  

There are 2 basic types in common usage. One is the simple emission  
tester.  It connects most of the elements together except the cathode  
and checks as to how much the cathode will put out.  That will often  
tell if the tube is weak.  The other is the mutual conductance tester.  
It simulates a circuit and is better.

Most have a shorted element test where you plug in the tube and tap it.  

They do not usually need calibration.  The easiest way to tell is to  
check several new tubes and see if they show way up in the good reagon.

Tubes are usually the last components to go bad unless another component  
causes them to go bad or the filament opens up which an ohm meter will  
tell.


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