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Testing Russian / Soviet tubes

M

marknoir

Active Member
Hi all

Recently I bought a bunch of different Russian and Soviet 6922 tubes. Some are Electro-Harmonix, some are Sovteks (under the RAM label), some are 6N23p Reflector. Since these tubes are scarce now because of the war, I wonder if what I got were some not so perfect ones. I have two tube testers, both calibrated: Eico 667 (so-so, I know), and B&K 747 (more serious). All of these tubes measure bad or borderline in Eico; in BK their behavior is strange: after a few minutes they measure bad or borderline, with needle going lower. If I hold the merit buttons for a while, the needle begins to go higher, sometimes into green (good) area. After I used RAMs in my ARC PH3 phono stage for a few hrs, and tested right away, they tested nearly good, but after a while went down. What is the deal with these tubes? Anybody has similar experience? The store I bought from told me that my testers are no good for testing “modern” tubes. I never have similar problems with my Amperex Holland, or a couple of cherished Mullards.
 
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do you have a known-good 6922 to compare readings to on the EIco ? NOS is ideal but known to be strong will serve. I also have a 667 and had some tubes that just test low, even known good NOS examples. What I've done with those is find a known good example and mess with the settings until I get a 100% reading, then test the unknowns. The specifics of how to do that properly are in the Eico manual under where it talks about how to develop settings for new tube types. Once you have workable settings just jot them down in a note.

also are you using the most current charts? BAMA has one from 1975 if I'm not mistaken, quite possibly its newer than whats in the roll chart in the unit itself.

also its not really advisable to hold the merit switch on that thing for very long. Some of the settings really flow a lot of current through the tubes, more than they are really meant to handle for any length of time. It even says in the manual to not hold that down longer than necessary to get a reading.

would also be worth confirming the heater voltage. On my 667 the "line" setting is a bit off, so if I set it to the center mark the 6.3v heater supply ends up a bit on the low side and some tubes are really affected by that. Voltmeter stuck into the octal socket on pins 4 and 5 with the tube you need to test installed will give you that answer.
 
Thank you for a fast reply. I have a separate thick chart rather than the roll. I have known Good tubes and they test well. The sellers keep telling me that these Russian tubes are “modern” and “special”… Both of my testers are calibrated.
 
gadget73 said:
do you have a known-good 6922 to compare readings to on the EIco ? NOS is ideal but known to be strong will serve. I also have a 667 and had some tubes that just test low, even known good NOS examples. What I've done with those is find a known good example and mess with the settings until I get a 100% reading, then test the unknowns. The specifics of how to do that properly are in the Eico manual under where it talks about how to develop settings for new tube types. Once you have workable settings just jot them down in a note.

also are you using the most current charts? BAMA has one from 1975 if I'm not mistaken, quite possibly its newer than whats in the roll chart in the unit itself.

also its not really advisable to hold the merit switch on that thing for very long. Some of the settings really flow a lot of current through the tubes, more than they are really meant to handle for any length of time. It even says in the manual to not hold that down longer than necessary to get a reading.

would also be worth confirming the heater voltage. On my 667 the "line" setting is a bit off, so if I set it to the center mark the 6.3v heater supply ends up a bit on the low side and some tubes are really affected by that. Voltmeter stuck into the octal socket on pins 4 and 5 with the tube you need to test installed will give you that answer.
Click to expand...
What’s BAMA? How do I find it? Thx
 
if real-deal 6922 test well, I'm guessing the Soviet ones are just different enough to not measure as a 6922. I have no experience with them but I do know that not all of the supposed equivalents are in fact exactly equivalent. Some of them are close enough to function anyway though.
 
gadget73 said:
do you have a known-good 6922 to compare readings to on the EIco ? NOS is ideal but known to be strong will serve. I also have a 667 and had some tubes that just test low, even known good NOS examples. What I've done with those is find a known good example and mess with the settings until I get a 100% reading, then test the unknowns. The specifics of how to do that properly are in the Eico manual under where it talks about how to develop settings for new tube types. Once you have workable settings just jot them down in a note.

also are you using the most current charts? BAMA has one from 1975 if I'm not mistaken, quite possibly its newer than whats in the roll chart in the unit itself.

also its not really advisable to hold the merit switch on that thing for very long. Some of the settings really flow a lot of current through the tubes, more than they are really meant to handle for any length of time. It even says in the manual to not hold that down longer than necessary to get a reading.

would also be worth confirming the heater voltage. On my 667 the "line" setting is a bit off, so if I set it to the center mark the 6.3v heater supply ends up a bit on the low side and some tubes are really affected by that. Voltmeter stuck into the octal socket on pins 4 and 5 with the tube you need to test installed will give you that answer.
Click to expand...
Life test could tell the tale.
 
marknoir said:
Hi all

Recently I bought a bunch of different Russian and Soviet 6922 tubes. Some are Electro-Harmonix, some are Sovteks (under the RAM label), some are 6N23p Reflector. Since these tubes are scarce now because of the war, I wonder if what I got were some not so perfect ones. I have two tube testers, both calibrated: Eico 667 (so-so, I know), and B&K 747 (more serious). All of these tubes measure bad or borderline in Eico; in BK their behavior is strange: after a few minutes they measure bad or borderline, with needle going lower. If I hold the merit buttons for a while, the needle begins to go higher, sometimes into green (good) area. After I used RAMs in my ARC PH3 phono stage for a few hrs, and tested right away, they tested nearly good, but after a while went down. What is the deal with these tubes? Anybody has similar experience? The store I bought from told me that my testers are no good for testing “modern” tubes. I never have similar problems with my Amperex Holland, or a couple of cherished Mullards.
Click to expand...
Buying tubes from sketchy sellers in the present market opens one up to poorly vetted misrepresented dregs from culling remnant stock.
 
6DZ7 said:
Kcheeeeeechchhckkkeecheeeeeeckkchhchiiiieeeeeeechchchch!!

Considering the equipment you have, why are you even bothering with dubious quality and quazii equivalent mystery tubes? Send 'em back. Or for more fun, borrow a neighbor's BB gun.
Click to expand...
FYI, up until the embargo started, nearly ALL manufacturers used Russian tubes in their new units. Be it current production Millards, Gold Lions, Harmonix or Tung-Sol, they were all made in Russia. The ones I have are no different. They are not quazy-equivalent, like 6n1p or 6c45p, they ARE equivalent.
 
Pio1980 said:
Buying tubes from sketchy sellers in the present market opens one up to poorly vetted misrepresented dregs from culling remnant stock.
Click to expand...
I bought them from reputable dealers, who’ve been in business for many years. I don’t want to mention the names at this point. Not from Ebay )))
 
marknoir said:
FYI, up until the embargo started, nearly ALL manufacturers used Russian tubes in their new units. Be it current production Millards, Gold Lions, Harmonix or Tung-Sol, they were all made in Russia. The ones I have are no different. They are not quazy-equivalent, like 6n1p or 6c45p, they ARE equivalent.
Click to expand...
Meaning they mostly came via Mike Matthews.
 
"A version (direct equivalent) of this tube was also produced in the Soviet Union as 6N23P (Russian: 6Н23П).

As of 2015 the tube was being produced in three versions in Eastern Europe - Slovakia by JJ Electronic (ex-Tesla), and in Russia: 6DJ8 for Sovtek and 6922 for Electro-Harmonix." from wiki

For what its worth, many years ago a guy from the radio club helped me test some tubes.
American 7591 and also a quad of SED 6L6.

He used his software updated Amplitrex AT1000 tester.

He stated that testing the SED tubes was not a direct test under the basic 6L6GC criteria in the machine's software...
I forget whether he tested my quad of EH 7591A...
 
I've used a few old stock Russian tubes over the years. Testing them with a western made tester can be a crap shoot for the reasons already posted.
Recently I had to test some 6P3S-E's. The original tubes in the amp measured right at the "Bad" line or just below using the 6L6GC settings. I bought a new matched quad of the same tube. When the new tubes arrived I tested them and they tested a quarter of the way above the "good" line. So that's all you can really do is compare readings between new and old I guess.
 
So the story ends this way: after doing a lot of reading, I’ve learned something that the sellers don’t want to accept. That old tubes do get bad just sitting on shelves. There are techniques to revive them, and I did. I was able to revive 4 out of 6. Also, old Russian tubes marked “6922” are not really 6922, they are 6dj8. Only the fairly recent production EH are apparently true 6922 with appropriate gain.
 
marknoir said:
That old tubes do get bad just sitting on shelves.
Click to expand...
Explain this!

I have tubes that I have had since the 60's unused and they still test strong today provided that they have not gone to air and the getter flash is still perfectly fine. :rolleyes:

It sounds like a rejuvinating technic used on old picture tubes which severly lowers the life of the tube. :idea:
 
marknoir said:
So the story ends this way: after doing a lot of reading, I’ve learned something that the sellers don’t want to accept. That old tubes do get bad just sitting on shelves. There are techniques to revive them, and I did. I was able to revive 4 out of 6. Also, old Russian tubes marked “6922” are not really 6922, they are 6dj8. Only the fairly recent production EH are apparently true 6922 with appropriate gain.
Click to expand...
Another source for new production 6922 is JJ E88CC
 
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