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Old 1st June 2009, 07:21 PM   #1
Space1 is offline Space1  United States
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Default Tube Tester's

I have been looking for someone to test tubes where I live , but they are a little hard to find. i was wondering if any of these would be good to buy. Can anyone recomend one of these, that are listed on E-Bay http://shop.ebay.com/items/__tube-te....c0.m14&_pgn=1

Any help would be appreciated,
Thank You ,
Matt
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Old 1st June 2009, 07:33 PM   #2
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What is your budget?

If you can swing the $$, look for a mutual conductance type tester, such as a Hickok or equivalent.

For a basic education, look here:

http://www.tone-lizard.com/Tube_Testers.html
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Old 1st June 2009, 08:34 PM   #3
Space1 is offline Space1  United States
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Thanks for the link alot of good info there. I tryed to google it but it can get pretty exausting wadeing thru the B.S. out there.There are way to many usless pages out there,and to many trying to sell you overpriced junk.
Thanks again ,
Matt
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Old 1st June 2009, 08:39 PM   #4
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Unless you have a lot of tubes, and in particular, a lot of different types of tubes to test, it is easy enough to make a rig for testing with a tube socket, a small power supply, and a multimeter.
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Old 1st June 2009, 08:55 PM   #5
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I have an Eico 666 "Satan's Choice" which is a "dynamic conductance" tester (a term they coined themselves, I think). Simpler than a mutual conductance tester, but better than a basic emissions tester. Look up the Eico on the site that boywonder posted.

I bring it up because it does a fairly decent job, the manual has a full schematic and theory of operation, they have no tubes inside, and they are not as desirable on eBay. A better value for the $$$ IMO. I've used mine to go through my stock of random NOS and used stuff to find any duds. Other than that, I mostly use it for testing tubes for friends. The readings are more meaningful when I have a known-strong tube to compare it with.
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Old 1st June 2009, 11:10 PM   #6
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I have an EICO 625 (basic emission tester) an a Hickok 600a which I use to test practically all of my tubes. The 600a is very versatile and does mutual conductance, but a decent one goes for about $200.

One interesting fact about the EICO 625....the switch tips are the same ones that were used on late 60's Telecasters (tophat style), so if you pick one up, the vintage switch tips (and probably switches) are worth more than what whole testers go for.

Speaking of my Hickok, I have not tested my 300b's on the 600a, since they are not in any of the roll chart data that I have. Can I test these as 45's with 5V on the filament?
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Old 2nd June 2009, 01:53 AM   #7
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My issue with tube testers is that they do not test under real working scenarios, except for a very few and VERY EXPENSIVE ones. TV-7, but try getting one for less than $1000.00 !!! A tester can be useful for weeding out plain DEAD tubes, but a problem may manifest itself at operating voltage that the tester does not reveal. Blow up an output tube once at 450V and see what else can happen to your amp. Also, to be safe, you should have your tester calibrated when you get a new one and few people are still doing that nowadays.
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Old 2nd June 2009, 02:34 AM   #8
rknize is offline rknize  United States
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I would say that is a bit of an exaggeration. Yes, the less-expensive only test the tube at one operating point and yes that won't uncover an issue with a tube that may not show up at that operating point. And so no, you can't take a box of tubes from eBay and/or someones' attic/barn, jam it in the tester, get a reading in a green and say it is super-awesome-A++++.

It will however give you an indication of the overall tube's health and more often than not (especially for NOS stuff) it's a pretty accurate conclusion. Yes, sometimes the tube will test fine in the tester but is all wrong in a circuit. If you use the tester right and it is calibrated, more often than not a "good" tube is indeed good and a "bad" tube is indeed bad. Obviously the final and most meaningful test is in the final circuit. I've tried weak 45s in the TSE and they work fine.

Other things that many testers don't test for is gas and leakage. The Eico does have a nice test for leakage and I have modified mine so that I can measure grid current and check for gas. The Eico is also very easy to calibrate. No special tools other than a meter are needed.
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Old 2nd June 2009, 02:46 AM   #9
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One of the other shortcoming of the Eico 666 is that like many other transconductance-type testers it is in effect measuring plate current with a 60Hz input signal. Many of the Hikocks are like this too. There are a few other that test at higher, more meaningful frequencies.
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Old 2nd June 2009, 03:50 AM   #10
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Quote:
Originally posted by bereanbill
My issue with tube testers is that they do not test under real working scenarios, except for a very few and VERY EXPENSIVE ones. TV-7, but try getting one for less than $1000.00 !!!
This is true, but they're not supposed to. They're designed as a screen to weed out the probably good from the definitely bad. To test under more stringent real working conditions, you need what's generally refered to as a tube analyzer. These include the RCA WT-100A, Daystrom/Weston CA-1630 and the New London 901A seen below. Hickok also made one but I forget the model.

The TV-7 is certainly not in this category, and is one of my least favorite testers. I've owned and used many different testers over the years. For some dumb reason the TV-7 has obtained cult status. Probably because it's small and military. My personal favorite is the Hickok USM-118B military cardmatic because it's very fast, durable and stays in cal for a long time.
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