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.
Thx
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.
Thx
Post removed.I sent a lot of money to different Ukrainian charitues. I’m also active in the info war against Kremlin propaganda. Tubes that I bought are at least 40 ys old and were sold by reputable places in the US. Do you propose I’ll take all my Russian tubes, even the ones I bought 10 ys ago and throw them out in protest? No new tubes are being shipped from Russia, but they are available still from Ukraine, btw. But I do appreciate you anger.
All of the Russian tubes that I bought in the last 15+ years came from a US vendor.
While not impossible for RAM tubes to be in Russia and be sold/shipped back to the US, it seems unlikely.
Sorry, can't help with the testing questions, I usually buy from vendors known to test well before selling.
While not impossible for RAM tubes to be in Russia and be sold/shipped back to the US, it seems unlikely.
Sorry, can't help with the testing questions, I usually buy from vendors known to test well before selling.
Yes, these tubes were in the US for many years. Especially RAM.
Sorry , i was reacting on the current news feed and overreacted.
I'm happy for your support of Ukraine and understand now that the tubes are old stock.
Maybe give the tubes a good burn in for 24 hours and see if that wakes them up.
I've also had luck giving the heater overvoltage for a minute or two... A weak tube became a good tube after 12V on the heater for a bit... YMMV but I've never burned out a heater yet.
If you can, attach pics... Sometimes the physical appearance can tell a lot about the life/condition of the tube.
By your description, it sounds like your tubes are at end of life, as their emissions goes down after being powered up.
BTW, the B&K 747 is a great tube tester but may need calibration. It sounds like the person you purchased the tubes from doesn't know much about tubes and or testers.
Good luck
By your description, it sounds like your tubes are at end of life, as their emissions goes down after being powered up.
BTW, the B&K 747 is a great tube tester but may need calibration. It sounds like the person you purchased the tubes from doesn't know much about tubes and or testers.
Good luck
There are some (including Morgan Jones) that recommend baking old tubes to activate the getter and remove any gassiness that developed over long periods of storage. I have not tried it but plan to do so with some of my unused NOS tubes that don’t test like new.
I think kodaBMX’s experience above with a short overvoltage burn-in supports the idea of “reactivation of something” in an old tube. Additionally, Wavelenght Audio advises 24 hours of burn-in of the 6AS7-types used in their power amps without output transformers, without HV applied, before powering up new tubes for service.
See M. Jones’s article on tube baking here: http://www.vacuumstate.com/fileupload/Baking_valves pix.pdf
There was also a diyAudio thread on the topic.
I think kodaBMX’s experience above with a short overvoltage burn-in supports the idea of “reactivation of something” in an old tube. Additionally, Wavelenght Audio advises 24 hours of burn-in of the 6AS7-types used in their power amps without output transformers, without HV applied, before powering up new tubes for service.
See M. Jones’s article on tube baking here: http://www.vacuumstate.com/fileupload/Baking_valves pix.pdf
There was also a diyAudio thread on the topic.
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I made a steady state, (not pulsed), valve tester once, and I put in a digital meter to measure the parameters. ECC88s of all types were a pain, causing me to question my design many times and include good regulation of everything. Putting an 88 in the tester and the values would repeatably and deterministically move around, never really settling. Initially I had AC heaters, I could detect the electric oven turning on and off, causing a small shift in transconductance, and daily shifts in the local AC voltage destroyed any possibility of repeatability of this sensitive parameter. Regulated heaters were the solution to that. Alternatively an analog meter would render those little changes to small to see 🙂 .
Our neighbour in Cuba used to do that with our CRT American TV in the seventies, reactivating the CRT. I can vouch that it really works, but it did not give a lasting effect, it would go bad again after a while.
All my tubes are Soviet NOS, bought from Ukraine sellers on eBay before the war (the Ukrpochta worked really well) , and I may have been lucky, but the ones I have used so far (6P3S-E, 6N8S, 6N9S) are well withing datasheet parameters.
Exactly. I built a "tube seasoner" that heats 10 6H13C's for 48 hours before retesting and use. My amps use 10 each. All the other tube elements
are grounded while being heated. I believe Ralph (Atma-Sphere) says it cures the cathodes. Luckily I procured a lifetime supply of tubes a few years ago before all the current turmoil. Would never consider building them now at current prices. Sorry if I strayed OT.