Tube Testers

[KX5JT]

After a year of being in this AM game, I have actually acquired a few boatanchor transmitters and recievers.  Radios that glow in the dark turn me on now.  I have a small collection of tubes salvaged from this and that and of course tubes that populate some rigs that need some work.

I'm thinking a tube-tester would be a very handy addition to my bench.  What kind do you guys have?  What do I want to look out for in such a device?  Seems some are way better than others as far as "emission" and "transconductance" etc.  Any advice and tips welcome!

[The Slab Bacon]

John,
Take the money that you are planning to spend on a tube tester and go down to the local gin mill and get a good load on and have some fun!!

Tube testers are ok for sorting out large piles of loose tubes, but........... they can get you into trouble when troubleshooting, as well as waisting tubes that still may be ok-fine for the circuits they're in. If you have a weak / bad tube it will show up in your circuit voltage and resistance checks. All of that circuit's voltages will be way off what they're supposed to be.  It is the absolute last peice of test gear that I reach for! !


                                                       The Slab Bacon

[KX5JT]

Roger Roger QSL I copy Q5!

[WV Hoopie]

John,

Just depends on how many pennies in the piggy bank. Have to agree the real test is if the tube works in the circuit! A few tube extenders make it easier to ck voltages, etc.

But if the cash is there, I've used a TV-7D/U for years to sort out the, "no doubt" bad tooobs, shorts or open filaments. Sticking a shorted tube in the circuit might not be good for resistors and stuff under the chasis. So when I bring home a few treasures from a fester, they go thru the tube tester before being put away for spares.

Craig,

[WA3VJB]

You can buy quite a few new spares for the price of a good tube tester, and then test by substitution into the questionable circuit when the time comes.

Also, check with any Radio-TV Museums around your area. 

Quite often they offer tube testing service as part of visitor outreach and recruitment of support.

Here's the one I'm associated with.

http://radiohistory.org/tubes.html

http://www.youtube.com/watch?v=IO48kJMrQy0

[k4kyv]

I use an ex-military TV7 D/U.  It is a mutual conductance tester, not a simple emission tester. I picked mine up for a few bux at a hamfest.  I had to replace a wirewound resistor and re-do all the adjustments, per the manual.  I have seen these same testers go for $$hundreds recently.

I also have a  couple of older versions of the tester, from the BC-610 era (forget the nomenclature).  Those will test most "vintage" tubes, but not many of the post-WW2 ones.  Army OD Green wrinkle finish.

If a tube tests moderately weak, I attach a little adhesive label to it and mark it as such and keep it in my spare tubes collection, or put it back in the equipment. If it shows up dead or nearly so, I usually do discard it.

A couple of years ago I tested all the tubes in my 75A-4.  Several tested weak, and I replaced them.  I was surprised how much that pepped it up.  Often, one weak tube won't make any obvious difference, but the accumulative effect of several questionable ones may noticeably degrade performance.

Like anything, use a little common sense with a tube tester. Even the TV7 D/U manual advises you not to automatically discard "weak" tubes, and that the last word is how well a tube works in the circuit.

Sometimes, conversely, a tube that checks perfectly good in a tester won't perform satisfactorily in the circuit.

[K3ZS]

I don't think I would spend a lot of money on one, however I picked up a Hickok transconductance type from a retired TV repairman for $15.   Then I bought a bunch of adapters to use with ancient tubes along with a vintage tube settings manual.    It was worth it for me because I have a lot of antique radios that I keep in running condition, with only a small supply of spare tubes for them.
I can test virtually any tube that was made for consumers and small transmitter tubes such as 807 and 6146.

[W2XR]

I use a military TV-7/U and a Western Electric-labled Hickok 539B. Both testers work fine and are of top quality, although I find the TV-7/U is a bit faster to use.

And I agree with Frank's (KB3AHE) and Don's assessment that these testers have to be used carefully and with discretion, as tubes that do test marginal or even sometimes weak are still perfectly usable in many less-than-critical circuits and applications. That said, I still test every tube in any piece of equipment I am servicing or restoring, and then make a subjective decision as to whether the tube remains in the circuit or not. Small-signal tubes do not go bad frequently, even after decades of service. Usually power output tubes are the first to go south.

I have no real experience with the more commonly available lower-end testers out there, by the likes of Eico, Paco, Precision Instruments, Heathkit, etc., and I cannot vouch for their accuracy or reliablity. The better testers such as the TV-7/U, the Hickoks, etc., are very pricey nowadays, with prices having largely been driven up by the tube guitar amp and audio crowd.

73,

Bruce

[Jim, W5JO]

I use a Western Electric KS15550 which does a real good job for what it is meant to do.  It is not the final word but is good for checking to see if your modulator tubes are balanced among other things.  Both of my transmitters use 811As and this checker will test them.  

If you find a weak tube in a circuit that requires two, then it might be best to replace it with one that is similar in operation.  You can find gassy tubes, noisy tubes and low transconductance tubes with a good tester.  If it is marginal and the operational position is not critical, then leave it alone.  The checker is very good to match a pair of tubes.

I remove all my gear from the cabinet once per year and visually check it for odor, cracked or burned resistors and, while I am there, I check the tubes.  If I find a weak one, I sub a known good one to see if there is a difference in operation.  If there isn't then I put the old one back, if there is I replace it.  It is just one tool in the arsenal to be used wisely.

[Pete, WA2CWA]

Unlike Frank, the tube tester is the first piece of test gear I pull out when I throw a newly acquired boatanchor up on the work bench. Pull all the tubes to weed out any perceived bad or weak ones. Once the boatanchor is up and running according to specs, I can always go back to any of the pulled questionable tubes and test them in the circuit. Then, either keep or disgard them. As Jim pointed out, a good transconductance tester is also useful in providing a closely matched pair if a matched tube set is needed. Personally, not having a good quality tube tester when working on boatanchors is like driving a car with absolutely no windows. A good quality Hickok, or the military TV-7 series, type of testers are a great addition to any test equipment arsenal of tools. The Western Electric (mostly made by Hickok), if you can find them, are also great test equipment.

[flintstone mop]

Troubleshooting an unfamiliar piece of equipment that is dead in the water, a tech might feel more comfortable with a tube tester, but all of the tube servicing I have done over many years has not required a tube tester.
Usually the problem turns out to be a circuit related problem not the tube.

BUT if you gotta have one, the TV-7U is a good standard and always lottsa $$$$.

Fred

[W7TFO]

I vote for any of the TV-7 () series, or any by Hickock.

Dennis

[N0WEK]

I've got a TV-2 military tester, but it's a major pain to set up and has WAY too many meters. If the thing ever craps out it'll be worth more to part it out than fix it.

I've got to build some sort of test jig for bigger power tubes like the 100th and 250th.

[WU2D]

I have had a few tube testers go through my hands, Heaths, Supremes & Eicos and I always felt the same way, who needs em. But having inherited so many tubes of dubious value and constantly repairing gear, I ended up borrowing a buddies Precision which he treated better than his wife. I was very impressed and had to get hold of one. The prices on Ebay for these boxes was out of sight but finally I spotted an old beat up one and paid 35 bucks.

Well what I got turned out to be little more than a pile of parts with the top and bottom wood warped and gone and the side dovetails were hanging by a thread. As my new worst EBAY purchase, I did not hold out too much hope. But after taking the wood apart and buying a couple of oak veneer panels from Home depot for 5 bucks, I sanded glued and and stained it. The electronics was not too bad. It took a lot of burnishing and cleaning. What emerged truly became one of my favorite instruments. I use it all of the time and it does not lie. Of course it is an old model and does not do 9 pins!

Mike WU2D

[Pete, WA2CWA]

AS a kid, I use to stand in front of this type for hours:

[KX5JT]

Hi Pete...

YES!! I remember our local K&B Drug Store having one just like that.   That was when I was a kid in the 1970s.  Good times.

[N0WEK]

AS a kid, I use to stand in front this type for hours:

There was one like that for sale in an antique mall in Des Moines a couple of months ago; for about $250!

[flintstone mop]

YUP Drug store testers always tested BAD.
Buy a new expensive horiz output tube and the TV still doesn't work

Fred

[W7TFO]

I remember an old Rodriguez cartoon years ago where some guy had plugged in a bunch of tubes and a crt into one of those drugstore jobs and was able to watch a ball game.  Then the clerk yells at him "One at a time, buddy!"

[Fred k2dx]

I like my TV-7 D/U. Years ago - when I was giving up on tubes - I gave one away. Now that I have boat anchors again, I was able to find a nice clean one for a reasonable price (NOT on ePay). Keep looking and you can locate one, overall they are a good yet simple tester. Military stuff is usually a good bet, the manuals are a big plus too. 

[N2DTS]

I have an old heathkit, which I like because it does tubes like 1625's and so on.
I only use it to compare tubes, and maybe check the filiments.
As a good /no good tester I suspect it.

I cant say I have had ANY tube problems in the last 20 years.

Brett

 

[KC4VWU]

I'd like to find a copy of that cartoon and have it enlarged to poster size! That's a real hoot!

I wouldn't necessarily shun the use of a good tube tester, but I agree that it shouldn't be the end word in problem diagnosis. It doesn't tell all. When I get a "new" piece, will I run all the tubes through the tester first? D@mn skippy! Eliminates the obvious junk in short order. Sometimes that internal short will not allow you to do voltage measurements before letting the smoke out of a resistor somewhere. However, I guess there are resistance checks that can be done first in some circumstances.

My advice is if you can get a good checker for < $50, and it is possible, go for it. Just don't hang yourself by spending an outrageous amount for one when you could use that money instead to buy more useful equipment like a really good sig gen or o-scope.

Phil

[K6JEK]

I see we're divided on this.  I'm with Pete.  I like to pluck out obviously weak tubes before I do a whole lot sleuthing.  They are, after all, one of the parts most prone to failure in old gear.

I also like to make sure that the tubes I'm using for swap tests aren't just as dead as the one I'm suspecting.

There are many good tube testers.  For my birthday this year I got a TV-10D/U in great shape.  That's the tester that came with instructions on how to destroy it rather than let it fall into enemy hands.

[Pete, WA2CWA]

I see we're divided on this.  I'm with Pete.  I like to pluck out obviously weak tubes before I do a whole lot sleuthing.  They are, after all, one of the parts most prone to failure in old gear.

I also like to make sure that the tubes I'm using for swap tests aren't just as dead as the one I'm suspecting.

There are many good tube testers.  For my birthday this year, I got a wonderful TV-10D/U in great shape.  That's the tester that came with instructions on how to destroy it lest it fall into enemy hands.

One additional point to this exercise of testing the tubes first is that it would confirm you have all the right tubes in all the right places.

The majority of the military manuals (706 at last count) I have include a "how to destroy" section.

[W2XR]

There are many good tube testers.  For my birthday this year I got a wonderful TV-10D/U in great shape.  That's the tester that came with instructions on how to destroy it rather than let it fall into enemy hands.

Gee, how does your wife know how to pick out such nice birthday presents?

73,

Bruce