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Post by larryguitar54 on Mar 19, 2022 23:54:19 GMT -5
I would like to hear from the extreme geeks here. The recent issue with tube scarcity and such has got me to thinking about tubes and not taking anything for granted. So I noticed I can purchase some vintage tube testers such as Hickock 600A and Triplett models. I grew up in the era of tube testers at my local Western Auto and such.
I know enough to teach myself how to use these things. I know how to use a multimeter and understand some basic electronics. However I am not going to be an amp tech.
However I would like to do more than the simple wooden stick tap test. I'd like the ability to put my several amps on a bench and take out the tubes one at a time and test them for actual values. Looking at my inventory of amps and tubes I am looking at as more than 50 tp 60 tubes in use or as spares.
I like the opinions of the experts on this board. What recommendations for a simple tube tester for the standard 6L6s and 12AX7s etc in most Fender type amps. Ebay has them for sale but it's new to me.
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Post by rickyguitar on Mar 20, 2022 0:08:12 GMT -5
I am also looking forward to replies on this.
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Post by larryguitar54 on Mar 21, 2022 20:51:28 GMT -5
As a follow up I did some research and ordered a Hickock 600A and a Precision NRI 70 testers. The Hickock was $500 and the NRI was about $150.
It's not a necessity but all this got me interested in the actual details about voltage and ohms and how tubes really work. I want to know the numbers. It's a new hobby and I will have fun with it. I'm looking forward to giving my restless mind something else to do.
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Post by jazzguy on Mar 21, 2022 23:55:59 GMT -5
I'd like to own one but never got around to buying one.
I do know the most important thing is to have them properly calibrated or your readings won't be close to accurate.
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Post by larryguitar54 on Mar 22, 2022 15:13:43 GMT -5
That's why I got 2 different testers. Basically I want to use tester to test a tester.
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Mar 22, 2022 16:15:11 GMT -5
Reading what an emission tester actually subjects valves to makes it seem a really bad idea. See Tomer, chapter 8 tubebooks.org/Books/Atwood/Tomer%201960%20Getting%20the%20Most%20Out%20of%20Vacuum%20Tubes.pdf His view, which I agree with, is that the most valid test for a valve is to check how well it performs in the its intended application circuit. Hence I think valve testers are something of a nonsense, sorry; they result in serviceable valves being disposed of because they don’t meet some irrelevant criteria, and bad valves to get put in amps and then cause trouble, because the tester only operates them at a voltage far lower than an amp. And they won’t test for essentials like hum, hiss, microphonics. All that’s needed to check a valve is a suitable amp (cathode biased is best) and a simple light bulb limiter. |
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Post by larryguitar54 on Mar 22, 2022 18:42:51 GMT -5
I don't totally disagree with you. Also others who actually have electronics labs have said the same thing. The true test is how the tube performs. And for the past 50 years that has been my basic test. My ears tell me when there is a problem.
My focus arises from my nature. I don't need a tester. I just wanted one because I am curious. When I take an interest in things I go a bit further. I like to read up on stuff and buy tools and learn about numbers. It's just a hobby to me. I actually have a microscope because I like to look at the stuff. When I lived further away from the city I had a decent telescope. When I got Covid I got an oximeter and decent digital thermometer so I could do readings.
None of it was essential and I"m not sure what I really learned. It's just what I enjoy doing.
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Post by roly on Mar 23, 2022 16:30:58 GMT -5
I have a Stark 966, it was made in Canada and the design was licensed from Hickock.
I calibrated it but basically just use it to test for shorts before sticking the tube in an amp to get a real world idea of how well it works.
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Post by Leftee on Mar 23, 2022 16:55:42 GMT -5
I have a Stark 966, it was made in Canada and the design was licensed from Hickock. I calibrated it but basically just use it to test for shorts before sticking the tube in an amp to get a real world idea of how well it works. Stark enterprises? Is it, like, bulletproof and stuff? I’ve got a Jet City Custom 5 that is a good tube tester. jetcitycustom.com/custom-5-picovalve/ |
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Post by rdr on Mar 23, 2022 20:49:27 GMT -5
I had a tube tester. Could use on a bunch of tubes and IIRC had a tube inside it. As I recall, the tester manual included the cal procedure, and I concluded that I'd have to take it to work to get it calibrated on the side. I never did and gave it away for the postage.
So you might want to look into whether necessary to get them calibrated.
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Post by larryguitar54 on Mar 26, 2022 0:59:00 GMT -5
So here is the update.
a.) The Precision NRI N70 is a nice little unit. However I know realize it is an 'emission' tester. This means it will give values for power tubes like 6L6 and rectifiers. However the 12AX7 and 12AT7 don't have sufficient voltage and therefore won't register. So bottom line is it is a quick down an dirty for power tubes only.
b.) The Hickok 600A arrived. I took a good look at it and decided some of the capacitors need replacing asap. But it works. Because it is a 'transductence?" tester it is good for all the normal tubes from 6L6s to 12AX7 and EL84s. You do need updated tube charts.
c.) Both require calibration but the manual and youtubes explain it well enough for my purposes.
Now with this behind me I am looking into the bias testers. This doesn't mean I will become an amp tech but it does mean I am a bit more knowledgeable about my equipment.
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Post by rickyguitar on Mar 26, 2022 4:14:30 GMT -5
Bias is tested with a voltmeter,multimeter, right?
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Post by larryguitar54 on Mar 28, 2022 19:49:01 GMT -5
I put the project on the back burner. I understand bias is tested with the tubes in place and power on. The basic idea is for the tubes to burn at that sweet spot between too hot and too cold. But in the meantime I was poking around cleaning contacts and dislodged one of the capacitors in the tube tester. I went ahead and order replacements for all four caps and then will go through it again. Normally I would replace the caps with all modern stuff but I wanted to see if I could get exact replacements of NOS. It's not easy because the components are 1950s era technology but enough time on Ebay and I think I got it close to original.
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pdf64
Wholenote
Posts: 557
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Post by pdf64 on Mar 29, 2022 13:57:18 GMT -5
I think it’s safe to state that modern caps and fixed resistors are almost universally far better spec and higher quality than vintage production. And I don’t perceive any role for mojo in test gear  Are these electrolytic caps? If so, NOS is not a good idea at all, they’ll have lost their insulating oxide layer and so will present as a short at initial power up. So they should best be reformed first, and may still end up being faulty. Vintage film / paper caps may not be much better. Of course, you may be lucky, nothing here is for certain |
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Post by larryguitar54 on Mar 29, 2022 16:59:46 GMT -5
Yup I came to the same conclusion after a bit of research. I'm replacing the caps with modern equivalents. Checked the specs and ordered mica caps on Mouser.
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