I was a member of the US military for 26 years (1974-2000), an Electronics Technician (E-8) and later and Electronics Technician Warrant Officer (W-3). I do not recall seeing this information. Please post a link to this reference so as to possibly refreshing my memory. Thanks in advance.
Your own tube tester
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haven't seen that one specifically but the idea of introducing problems by messing with stuff that isn't having a problem is not lost on me. The more you pull and plug in tubes, the more those contact surfaces wear. I don't regularly pull my own stuff for checking. Mostly that is reserved for unknown tubes that I might want to put in something, or confirming a problem.
recent example, and why I know the test data for a 7199 is wrong on the Eico 667. I had a Dynaco ST-70 here for some work. Listening at low volumes it sounded fine. When I gave it the beans it started to sound noticeably funny. A quick voltage check turned up nothing obvious. On the scope I was getting significant asymmetrical clipping at well below the 30-ish watts I expect to see from one. Some further poking showed a normal sine output from the plate of the 7199 inverter and a much weaker one from the cathode of the inverter. After I figured out the setting problems on the tester, what it told me was there was very significant heater-cathode leakage on the triode side of the 7199. It was so bad that the cathode was effectively working into a much lower impedance load than it should have been, and the output was weak as a result. Different tubes fixed the problem and it performed like it should have.
if I'd just tested the tubes before I even bothered to turn the amp on it would have saved me some time.
recent example, and why I know the test data for a 7199 is wrong on the Eico 667. I had a Dynaco ST-70 here for some work. Listening at low volumes it sounded fine. When I gave it the beans it started to sound noticeably funny. A quick voltage check turned up nothing obvious. On the scope I was getting significant asymmetrical clipping at well below the 30-ish watts I expect to see from one. Some further poking showed a normal sine output from the plate of the 7199 inverter and a much weaker one from the cathode of the inverter. After I figured out the setting problems on the tester, what it told me was there was very significant heater-cathode leakage on the triode side of the 7199. It was so bad that the cathode was effectively working into a much lower impedance load than it should have been, and the output was weak as a result. Different tubes fixed the problem and it performed like it should have.
if I'd just tested the tubes before I even bothered to turn the amp on it would have saved me some time.
Dswankey
Lunatic Member
I have an Accurate Instrument Co. Model 257. It's a simple "emissions tester" which I picked up for next to nothing years ago at an Estate Sale.
I don't test tubes all that often only when I find some, I also have access to a routinely used calibrated Hickok at my buddies shop
I really like testing tubes, I'm not sure why but I find it fun,
I don't test tubes all that often only when I find some, I also have access to a routinely used calibrated Hickok at my buddies shop
I really like testing tubes, I'm not sure why but I find it fun,
AmadeusMozart
Well-Known Member
I'm sorry, cannot recall which MIL Handbook I read it - did not see it immediately in MIL-HDBK-217F so it must have been in one of the other ones that I deleted from my drive. It may have been in one of the older 217 handbooks as 217F is from 1991 by which time tubes had gone out of fashion.
I'm a novice when it comes to tubes but somehow have acquired a couple of dozen tube amps, receivers, tuners and have even managed to build a couple of my own. Your comment "When I gave it the beans" made me snort backwards about the beans I have given myself a few times when not being careful. Gave me a good chuckle - and a good reminder - that those 'beans' do hurt and can be deadly when we are not careful. Apologies for getting off topic.
I had a 667 and a 666 and got rid of it, it would give you weird reading sometimes. I tried to find the quote from Tone Lizard as Eico testers being evil in some regards, but it must have been removed or is somewhere else. I ended up using a Sencore Might Mite TC114 as an emissions tester to weed out bad tubes and then if I want more accurate readings I get out my Hickock 600A. I had a few B&K 606 and 625 which would show shorts on rectifier tubes that were false. So those are gone also. Use more than one tester before chucking a tube in the garbage.
That article is still around somewhere. Talked about how the original settings were pretty abusive for some tubes, including the 12AX7. And how the chart had some drastic typos, like 25 volts filament setting for an old balloon tube instead of 2.5 volts. If you use the last completed compilation from the Bama site, it can lead to better readings.
Dswankey
Lunatic Member
Might this be it
http://tone-lizard.com/eico-tube-testers/
I always liked this article
http://tone-lizard.com/tube-testers/
I haven't had any real trouble out of the switches on mine, but there sure are a lot of them and they all have a bunch of contacts. Only thing I ever did with mine was give them a wash with CRC QD cleaner when I got the thing years ago. Its the same construction as a rotary switch anyway, just turned 90 degrees. Phenolic wafer with fixed fingers and a rotating disc that connects various ones together.
This may be of some use too
http://conradhoffman.com/EicoTubeTesterSettings.xls
it was developed by @ConradH and its useful for creating your own test settings. The spreadsheet will tell you exactly what voltage and current its testing your tubes with. Helpful if you want to test them under different parameters. I also use my copy to store frequently-used settings so I don't have to look it up each time.
This may be of some use too
http://conradhoffman.com/EicoTubeTesterSettings.xls
it was developed by @ConradH and its useful for creating your own test settings. The spreadsheet will tell you exactly what voltage and current its testing your tubes with. Helpful if you want to test them under different parameters. I also use my copy to store frequently-used settings so I don't have to look it up each time.
I recently bought a Hickok 539A on ebay. I am sending it back because it doesn't work but did prompt some questions when I was playing with it.
How do you test a tube that is not included on the roll chart in the tester? I wanted to test a 12AX7 but it was not on the chart. Same for a pair of 300B that I wanted to test.
How do you test a tube that is not included on the roll chart in the tester? I wanted to test a 12AX7 but it was not on the chart. Same for a pair of 300B that I wanted to test.
Dswankey
Lunatic Member
Can't speak to the 300B but the 12AX7 was/is a very popular tube not sure why you didn't see it on the chart
https://stevenjohnson.com/hickok/data.htm
Didn't the USAF and Navy have hours of use specifications for testing tubes? Depending on the tube and its application?
I can't answer for the Air Force as I do not play golf but if the Navy had such a thing while I served it was ignored, and rightly so. While underway most electronic equipment, vacuum tube or solid state, was in use 24/7 if it was functional. We technicians, while underway, could only get the equipment for any kind of maintenance when it broke and then we were on the clock.
BrassTeacher
Uncurable Tweaker
Check online for "supplemental data" for your tester. When I bought my 800A, the seller sent printouts of the supplemental data (newer tubes), obsolete tubes, which was valuable in testing a few older 4 and 6 pin tubes, and a set of data for testing quite a few of the European tubes (Not Russian though). Also, double-check your roll cart. I couldn't find 5881 at first, then after I tested all my 5881 using 6L6 settings (They're identical), lo and behold the next day 5881 showed up on my roll chart...