[gibosi]

What I am finding is a much longer manufacturer code+numeric postamble that became the date code. No mention of 2 letter date codes for Tung-sol tubes, here's what I found:

The first describes the 6 digit mfgr (322 for Tung-sol)/date code scheme, the 2nd has links to the articles I'll include below, that further expand the lists of mfgr codes, IDK about date codes...
https://community.klipsch.com/index...ung-sol-tubes/&do=findComment&comment=2230674


Do these 3 articles combined have enough info to decode the 6 digit Tung-Sol Code?
https://community.klipsch.com/index...ung-sol-tubes/&do=findComment&comment=2231049

http://www.triodeel.com/eiacode.htm

https://www.tubemuseum.org/SearchResults.asp?Cat=30

http://www.tubemaze.info/deciphering-european-tube-date-codes/

So I wonder if @bcowen has a Tung-Sol labeled 6520 made by RCA with RCA date code NF, for June 1963, from the chart I posted back a few posts from here...

Is this an example of RCA made 6520 tubes labeled as Tung-Sol?

It seems that you really really want the date code on that 6520 to be an RCA date code!

But unfortunately there is nothing new in the links you have posted.....

I think the simplest explanation fits the facts the best. To my knowledge RCA never made a 6520, but Tung-Sol did. So that 6520 was manufactured by Tung-Sol, not RCA. And then I think you insult all the many talented people who worked at Tung-Sol by implying that they were either too lazy or not capable of devising a date-code system tailored specifically to the needs of Tung-Sol? Again, TS devised this system and it is theirs and theirs alone. But unfortunately the key to deciphering these codes is not known to me....

 

[hmscott]

...I think the simplest explanation fits the facts the best. To my knowledge RCA never made a 6520, but Tung-Sol did. So that 6520 was manufactured by Tung-Sol, not RCA. And then I think you insult all the many talented people who worked at Tung-Sol by implying that they were either too lazy or not capable of devising a date-code system tailored specifically to the needs of Tung-Sol? Again, TS devised this system and it is theirs and theirs alone. But unfortunately the key to deciphering these codes is not known to me....

That's the missing info I needed to know, that the 6520/5998 tubes were only made by Tung-sol, and so no RCA created date code would be found.

Yes, I am learning, and trying to fit all the pieces together, that's how my brain works. Occasionally I put together the puzzle looking for answers, and I am doing it without enough pieces of information to solve the puzzle.

I wasn't looking to insult anyone, I was looking for feedback and corrections to what I was thinking, and I very much appreciate the course correction. There's no need to be upset when I speculate like that, it's a sign I don't have the answer and I am trying to find it by putting together the pieces I have, to assist me in finding the missing pieces.

I'd like to know as much as I can before buying a 6520, or a 5998, so I don't end up making the mistakes when spending my meager funds.

Sorry for the long gap in my reply, I just woke up after literally passing out from 90 minutes in the local Hospital's Respiratory Therapy "Cabinet of Doom". I never knew my lungs could hurt. I still feel it 10 hours later. I normally take 3 inhalers 2x a day, so I'm already overtasking my lungs, this test really flipped me over - but I completed it and passed. No t-shirt for completion, but I did get a nifty Respironics device to aid in using one of my inhalers.

My graph compared to "normal" shows I'm under capacity by about 20% or so - eyeballing the graphs showing on the screen of the PC controlling the "Cabinet of Doom", while shut in inside the walls of the transparent cabinet:

Spoiler: Photo of the Cabinet of Doom

Photo from The British Lung Foundation

I couldn't finish the Elevated Treadmill Test, disabled + arthritis + lungs did me in early, but this one I was determined to follow through to the end. Perhaps not my best choice. So it is nice to know I have the support and caring of my internet friends to come back to, to cheer me up.
Thank you for the passionate and caring response, I do appreciate the correction of my postulate, and I've updated my earlier post with the correction.

 

[Ripper2860]

So the fact that you posted after your tests indicates that you made it through the hardest part...

where they fill it full of water and wait for you to escape.

 

[hmscott]

So the fact that you posted after your tests indicates that you made it through the hardest part...



where they fill it full of water and wait for you to escape.

Yup, complete with air/gas tanks - part of the test injects gases into the air tube after mixing behind the scene - breathing in and out for about 5 minutes with the Cabinet sealed.

When they sealed the door I asked them if I will get my divers certification as part of the test, he said we'll wait for the cabinet to fill up before starting the next test!

The situation reminded me of Agent 86 and 99 sealed in a phone booth while it was filling up with water, they sure made it look like a lot of fun. Thinking about that funny scene kept me happy and calm while waiting for the gases to mix.


I'll say it is nice to have it over, at least until the next one in 6-12 months!

Plenty of time for more 6AS7G's until then!

 

[LoryWiv]

That's the missing info I needed to know, that the 6520/5998 tubes were only made by Tung-sol, and so no RCA created date code would be found.

Yes, I am learning, and trying to fit all the pieces together, that's how my brain works. Occasionally I put together the puzzle looking for answers, and I am doing it without enough pieces of information to solve the puzzle.

I wasn't looking to insult anyone, I was looking for feedback and corrections to what I was thinking, and I very much appreciate the course correction. There's no need to be upset when I speculate like that, it's a sign I don't have the answer and I am trying to find it by putting together the pieces I have, to assist me in finding the missing pieces.

I'd like to know as much as I can before buying a 6520, or a 5998, so I don't end up making the mistakes when spending my meager funds.

Sorry for the long gap in my reply, I just woke up after literally passing out from 90 minutes in the local Hospital's Respiratory Therapy "Cabinet of Doom". I never knew my lungs could hurt. I still feel it 10 hours later. I normally take 3 inhalers 2x a day, so I'm already overtasking my lungs, this test really flipped me over - but I completed it and passed. No t-shirt for completion, but I did get a nifty Respironics device to aid in using one of my inhalers.

My graph compared to "normal" shows I'm under capacity by about 20% or so - eyeballing the graphs showing on the screen of the PC controlling the "Cabinet of Doom", while shut in inside the walls of the transparent cabinet:

Spoiler: Photo of the Cabinet of Doom

Photo from The British Lung Foundation

I couldn't finish the Elevated Treadmill Test, disabled + arthritis + lungs did me in early, but this one I was determined to follow through to the end. Perhaps not my best choice. So it is nice to know I have the support and caring of my internet friends to come back to, to cheer me up.
Thank you for the passionate and caring response, I do appreciate the correction of my postulate, and I've updated my earlier post with the correction.

Wishing you a return to robust health and hoping music is always a healing force.

 

[hmscott]

Wishing you a return to robust health and hoping music is always a healing force.

Thank you, and I agree, music is such a positive and healthy contribution to a healthy and happy life, such a joy in every aspect and time of life.

 

[hmscott]

The 4 6N13S (5AS7G) tubes ordered from 12-rocketman shipped from Russia were delivered much faster than I expected, instead of 3 weeks it took only 10 days:

Feb 5, 2022 4:40 pm Acceptance - Received by Russian Post Moscow
Feb 15, 2022 3:19pm Delivered

I am testing each of the Russian 6AS7G tubes with a CBS JAN CHY 5692 in the TA-26:

6N5S / 6N13S / 6AS7G / ECC230 SVETLANA TUBE NOS OTK USSR RARE 1950`s lot 1pc. US $19.84 - No paper, fits photo, exact 1950's year?

6N13S / 6AS7G / ECC230 TUBE SVETLANA Double Triode NOS DATE 1960`s USSR Lot 1pc. US $13.69 - ID via Big "C", exact 1960's year?

6N13S / 6AS7G / ECC230 SVETLANA TUBE Double Triode NOS OTK USSR Lot 1pc. US $12.88 - No box/paper, ID via Little "C" on Tube, year?

6N13S /6AS7G /ECC230 /6N5S TUBE SVETLANA TRIODE NOS IN BOX OTK lot 1pc. or more US $14.58 Paper says 1986, OTK Stamp on Box says 1988

The tubes were well packed in 2 medium boxes in a side/side bundle using bubble wrap and styrofoam, with 3 6N13S tubes rolled in bubble wrap, 1 6N13S in original sealed box, 1 6N13S in a cut box. I am trying to ID each of the 3 rolled up + 1 of the boxed tubes, as there was no written ID or packing slip.

Does anyone know how to read the Russian/Svetlana tube markings / stamps to establish build date? The "C" has a mark on either side:

"V C 61", 'XI C 63", "VII C 58", " C 6H13C over 85 12", " C 6H13C over 88 03"

The last one has the nicest sealed box/stamps on the outside, with a date written in pencil - 88.08, and a 1988 stamp on the box and the tube, along with: " C 6H13C over 88 03" etched into the tube.

There are many other stamps on each tube, but I'm hoping those unique "C" marks will allow 12-rocketman to tell me which tube matches which listing, and give me a memory cue to link age to markings for each tube.

12-rocketman also gave me a free 6H13C tube - in lieu of a $17 refund for combined shipping, besides the 4 tubes listed, which helps make tube ID'ing that much more fun.

The 1953 Melz 6N8S from 12-rocketman to pair with the Russian tubes on the TA-26 was also packed into the boxes. A Russian manufacturers product paper was rolled around the tube says 1952 + OTK Stamp 1957, eBay listing says 1953:
6N8S / 6SN7 / 1578 MELZ TUBE HOLE PLATE NOS METAL BASE DATE 1953 Lot 1pc.

The TA-26 is cooling down for the first test run, I wonder which 6N13S Svetlana "C" tube I should pair up with the 5692?, or should I test with the 1953 Melz? I think I'll start by swapping in the 1953 Melz, to see how it plays with the '50 Jan RCA 6AS7G.

 

[JTbbb]

The 4 6N13S (5AS7G) tubes ordered from 12-rocketman shipped from Russia were delivered much faster than I expected, instead of 3 weeks it took only 10 days:

Feb 5, 2022 4:40 pm Acceptance - Received by Russian Post Moscow
Feb 15, 2022 3:19pm Delivered

I am testing each of the Russian 6AS7G tubes with a CBS JAN CHY 5692 in the TA-26:

6N5S / 6N13S / 6AS7G / ECC230 SVETLANA TUBE NOS OTK USSR RARE 1950`s lot 1pc. US $19.84 - No paper, fits photo, exact 1950's year?

6N13S / 6AS7G / ECC230 TUBE SVETLANA Double Triode NOS DATE 1960`s USSR Lot 1pc. US $13.69 - ID via Big "C", exact 1960's year?

6N13S / 6AS7G / ECC230 SVETLANA TUBE Double Triode NOS OTK USSR Lot 1pc. US $12.88 - No box/paper, ID via Little "C" on Tube, year?

6N13S /6AS7G /ECC230 /6N5S TUBE SVETLANA TRIODE NOS IN BOX OTK lot 1pc. or more US $14.58 Paper says 1986, OTK Stamp on Box says 1988

The tubes were well packed in 2 medium boxes in a side/side bundle using bubble wrap and styrofoam, with 3 6N13S tubes rolled in bubble wrap, 1 6N13S in original sealed box, 1 6N13S in a cut box. I am trying to ID each of the 3 rolled up + 1 of the boxed tubes, as there was no written ID or packing slip.

Does anyone know how to read the Russian/Svetlana tube markings / stamps to establish build date? The "C" has a mark on either side:

"V C 61", 'XI C 63", "VII C 58", " C 6H13C over 85 12"

The last one has the nicest sealed box/stamps on the outside, with a written in pencil 88.08, and a 1988 stamp on the box and the tube, along with: " C 6H13C over 88 03" etched into the tube.

There are many other stamps on each tube, but I'm hoping those unique "C" marks will allow 12-rocketman to tell me which tube matches which listing, and give me a memory cue to link age to markings for each tube.

12-rocketman also gave me a free 6H13C tube - in lieu of a $17 refund for combined shipping, besides the 4 tubes listed, which helps make tube ID'ing that much more fun.

The 1953 Melz 6N8S from 12-rocketman to pair with the Russian tubes on the TA-26 was also packed into the boxes. A Russian manufacturers product paper was rolled around the tube says 1952 + OTK Stamp 1957, eBay listing says 1953:
6N8S / 6SN7 / 1578 MELZ TUBE HOLE PLATE NOS METAL BASE DATE 1953 Lot 1pc.

The TA-26 is cooling down for the first test run, I wonder which 6N13S Svetlana "C" tube I should pair up with the 5692?, or should I test with the 1953 Melz? I think I'll start by swapping in the 1953 Melz, to see how it plays with the '50 Jan RCA 6AS7G.

That’s probably a nice Melz tube you have, but it isn’t a 1578.

 

[hmscott]

That’s probably a nice Melz tube you have, but it isn’t a 1578.

Yup, the 1953 Melz 6N8S really does sound great. I swapped out the CBS JAN 5962 for the 1953 Melz 6N8S, and the Melz is really holding up nicely. I've not had it in long, but it has a similar clear impactful sound, without any unwanted resonances. A very nice sounding tube.

The Melz 1578 is next.

What price do you think would be fair for a great single tube 50's Melz 1578?

 

[JTbbb]

Yup, the 1953 Melz 6N8S really does sound great. I swapped out the CBS JAN 5962 for the 1953 Melz 6N8S, and the Melz is really holding up nicely. I've not had it in long, but it has a similar clear impactful sound, without any unwanted resonances. A very nice sounding tube.


The Melz 1578 is next.

What price do you think would be fair for a great single tube 50's Melz 1578?

Well that’s a million dollar question! I guess I wouldn’t be too far off the mark if I say $125 ’ish plus. But be careful it’s the real deal. To many out there claiming a 1578, when it is not. Not too far back in one of the 6sn7 threads, there is guidance on how to spot a true 1578 and which years are the best.

 

[hmscott]

Well that’s a million dollar question! I guess I wouldn’t be too far off the mark if I say $125 ’ish plus. But be careful it’s the real deal. To many out there claiming a 1578, when it is not. Not too far back in one of the 6sn7 threads, there is guidance on how to spot a true 1578 and which years are the best.

12-rocketman did such a great job with these tubes, I'll probably give these a chance, for the pair he offered me he didn't specifiy a year. I found this old eBay Sold listing by 12-rocketman on my own:

MATCHED PAIR 6N8S / 6SN7 / 1578 MELZ TUBE HOLE PLATE NOS METAL BASE DATE 1954

12-rocketman 's offered them to me for $300/pair. I only need one tube and IDK if I really need a backup. Perhaps he'll find a single tube to sell me

 

[JTbbb]

12-rocketman did such a great job with these tubes, I'll probably give these a chance:

MATCHED PAIR 6N8S / 6SN7 / 1578 MELZ TUBE HOLE PLATE NOS METAL BASE DATE 1954


12-rocketman 's offered them to me for $300/pair. I only need one tube and IDK if I really need a backup. Perhaps he'll find a single tube to sell me

From what I can see they look genuine. You will just need to tie down the year.

Edit: You could always sell one on.

 

[bcowen]

Does anyone know how to read the Russian/Svetlana tube markings / stamps to establish build date? The "C" has a mark on either side:

"V C 61", 'XI C 63", "VII C 58", " C 6H13C over 85 12"

Those are the dates. 1961, 1963, 1958, and 1985. In earlier tubes the month is in Roman numerals to the left of the Winged C logo, and the year to the right. In later years it was year/month under the logo in regular numeric text. There's nothing cryptic about Russian date codes (at least with Svetlana, Foton, and Melz), it's mostly an issue of whether they're still visible or not.

 

[hmscott]

From what I can see they look genuine. You will just need to tie down the year.

Edit: You could always sell one on.

Yeah, I could sell one, but if I do it probably won't be right away.

I think he doesn't show photo's of a specific tube month/year so he doesn't need to reshoot the photo's for every different year listing. For the pair he offered me he didn't specifiy a year. I found the old eBay Sold listing by 12-rocketman on my own.

He probably has more than one "box" and even the year may vary, as all the years of 6H13C's I received are earlier than I expected, a nice surprise:

Those are the dates. 1961, 1963, 1958, and 1985. In earlier tubes the month is in Roman numerals to the left of the Winged C logo, and the year to the right. In later years it was year/month under the logo in regular numeric text. There's nothing cryptic about Russian date codes (at least with Svetlana, Foton, and Melz), it's mostly an issue of whether they're still visible or not.

I hoped it was that easy, but you never know, so I thought I'd ask first before stating the obvious, incorrectly. Thank you.

Now I need to match each 6H13C tube to the correct listing I bought... some seem like an easy match, a couple don't, so I've asked 12-rocketman which is which.

If I get stuck I'll post some photo's later.

He probably thought I knew enough to figure it out for myself, so he didn't bother labeling them.

 

[bcowen]

Now I need to match each 6H13C tube to the correct listing I bought... some seem like an easy match, a couple don't, so I've asked 12-rocketman which is which.

What difference does it make?