OK I give up. Date this Sylvania (Silvertone) tube?

[King Fan]

Sure, the internet tells me 312 is Sylvania, and the chrome-top with the letter-number-letter code under the stop sign confirms it.

But I can't find a description of the 3-digit code below the 312 on the base. YWW? 1958? 1968? or ???

 

[muscmp]

i'd say 68, 13 week. but, still could be 58. do you know what silvertone amp it came out of?

here is the wiki info on 6v6gt:

https://en.wikipedia.org/wiki/6V6

play music!

 

[King Fan]

i'd say 68, 13 week. but, still could be 58. do you know what silvertone amp it came out of?

here is the wiki info on 6v6gt:

https://en.wikipedia.org/wiki/6V6

play music!

Thanks. No idea, unfortunately, where it came from. '68 is very plausible, and it's going into my '67 Vibro Champ, so that'd be good. The 'style' of lettering looks old. The clean state suggests new. (Look at those silvery pins.) I need to learn more about Sylvania's 3- and 4-digit date codes.

 

[theprofessor]

I'm thinking it's a 1958, 13th week. That gray glass coating is a 1950's thing, as far as I know. Here is a very similar-looking CBS-Hytron 6V6GT from 1959, also with the octagonal logo on the top:

And here is an RCA 6V6GT from 1957 or so, though the octagonal logo is on the side.

 

[theprofessor]

it's going into my '67 Vibro Champ

In my opinion, that's a great tube for a Vibro Champ. I tried several different vintage types, including RCA, Tung-Sol, CBS-Hytron, and Sylvania, and a Sylvania like that one was what I ended up with in there. Of course it depends on the current draw and the like, but I really like those Sylvanias for that application.

(Look at those silvery pins.)

Yeah, those pins are gorgeous! Looks unused. Hopefully the plates will draw just the right amount of current.

 

[Bendyha]

1958 would be my guess if it has the GT rating, by 1968 Sylvania would only have been making 6V6GTA or 6V6GTY, with the clear glass, like da prof said.

 

[King Fan]

I'm thinking it's a 1958, 13th week. That gray glass coating is a 1950's thing, as far as I know.

Of course it depends on the current draw and the like, but I really like those Sylvanias for that application.

1958 would be my guess if it has the GT rating, by 1968 Sylvania would only have been making 6V6GTA or 6V6GTY, with the clear glass, like da prof said.

Thanks, gents, super helpful. I agree it has a '58 thing going on. And it does sound killer in the Vibro Champ. The tech I got it from said it tested 'off the chart' on his transconductance tester.

He thought ti was a Tung-Sol due the the stop sign on top. I didn't know much about the chrome-tops, but that and the factory code clearly say Sylvania. I had actually thought the stop sign was strictly an RCA thing (when seen on the side of the tube, faint and silvery, as in the Prof's photo, with its -- to me -- mysterious system of breaks in the outline.)

Then there's the now-garbled page from the tube museum site that says that Tung-Sol and RCA both used the octagon. As regards CBS/Hytron, there's (link removed) clear example of a case where they clearly re-labeled Sylvania tubes.

Tube identification is like archaeology -- knowledge and science mix with lore and imagination in a fascinating tangle.