The 6SN7 Identification Guide

[Oskari]

Hi
RCA 6SN7GTB data code ML. Any ideas about Year of made?

Apparently that's a shipment date. October 1961.

 

[Kryl0071]

Thanks!

 

[peter-a]

I came across these Tung Sol 6sn7gt's and was wondering if anyone can tell me a bit more about these
What period? Same sound as mouse ear version?

 

[eschell27]

Hello, can anyone verify that this is considered a Sylvania 6SN7GT "bad boy" ?
 

 

[brad1138]

I am confused on tube readings when I am buying used. A popular tester gives results like 2500/2400 where 2600/2600 is typical new/best. I use to think it was 2400 out of 2500, but now I think those numbers are 2 different parts/aspects of the tube. Can anyone enlighten me on this?

Thank you.

 

[CZ4A]

I am confused on tube readings when I am buying used. A popular tester gives results like 2500/2400 where 2600/2600 is typical new/best. I use to think it was 2400 out of 2500, but now I think those numbers are 2 different parts/aspects of the tube. Can anyone enlighten me on this?

Thank you.

Twin-triode tubes like 6SN7s are essentially the electrical elements of two triode tubes placed in one envelope. For example, the 6SN7 combines two 6J5 triodes (the electrical element) into one tube. If you look at this picture of a 6J5GT you'll see one plate structure in the glass while a 6SN7GT has two.

The 2500/2400 in your used example signifies that one triode has a transconductance rating of 2500 micromhos and the other triode is rating at 2400 micromhos. The typical new rating is 2600 micromhos for each triode.

There are other types of tubes that combine two to four dissimilar electrical elements into one envelope and those will have dissimilar new ratings. However, those types of tubes are uncommon in headphone amps.

 

[brad1138]

Thank you that makes sense, so how big of a deal is it when the number get far apart? like if you have a tube rated at 2500/2200 and 2600/2600 is "peak", is that tube "unbalanced"? Also, is there a reason 1 side would degrade faster than the other?

 

[circatubes]

I came across these Tung Sol 6sn7gt's and was wondering if anyone can tell me a bit more about these
What period? Same sound as mouse ear version?

Those are Raytheon VT-231 era 6sn7gt , 1940's.
Very nice tube.

 

[circatubes]

Hello, can anyone verify that this is considered a Sylvania 6SN7GT "bad boy" ?

Yes.

 

[circatubes]

Quote:

Originally Posted by Frihed89 /img/forum/go_quote.gif It is my understanding that only a small fraction of the Slyvania JAN-CHS-6SN7GTs are "bad boys". Is your description of the JAN-CHS-6SN7GT or the bad boy part of the production run? If you are describing the bad boys, then how do the other JAN-CHS-6SN7GTs differ in construction from the bad boys?

Hi there -

Bad Boys were only made in
- late 1951
- 1952
- early 1953

Thus they will be marked with either
- '1xx' (late week production numbers only),
- '2xx' (all 52 weeks of the year) or
- '3xx' (early week production numbers only)
date codes.

They can also be JAN-rated and thus be marked JAN-CHS-6SN7GT.

For construction details, look to the section on Bad Boys in post #3 and compare against that for 'normal' Syl 6SN7GTs.

Nice post, To add, There was actually a scarce run of Bad Boys in 50'. black plates.
Also grey plate 3- hole Bad Boys in 51' and maybe 52' if I remember correctly.
I also have a tube with one 2-hole plate and one 3-hole plate, think 51' will check.

 

[Kryl0071]

Hi
Any idea about data of production Sylvania Gt vt-229?

 

[winders]

Hi
Any idea about data of production Sylvania Gt vt-229?

That's a 6SL7 tube.....

 

[circatubes]

Thank you that makes sense, so how big of a deal is it when the number get far apart? like if you have a tube rated at 2500/2200 and 2600/2600 is "peak", is that tube "unbalanced"? Also, is there a reason 1 side would degrade faster than the other?

Hi
Any idea about data of production Sylvania Gt vt-229?

Just a labeled for the military 6sl7gt, prob 1941-45.

 

[Kryl0071]

Thank you! Is it a good idea to buy some?

 

[circatubes]

Quote:

Originally Posted by augustwest /img/forum/go_quote.gif adhoc - I have a 6sn7 tube that I am hoping you might help me identify? It is a brown base, medium bottle with trianlular black plates. The only indentifing markings on it are "6sn7 / Tele - Rad" in small point type face. - augustwest

Hope ya got my email.

If the spam filter ate it, it's almost certainly a Tungsol WGT or WGTA.

Yes, have had many Tel-rad brown base tri black plate, WGT*, all Tung-Sol