Sylvania 6V6GTA date code.

[fretknot]

Anyone have any info on Sylvania tube date coeds? Trying to identify the age of this one. There are two possible references: 'DEW', or 'ka'. I'm thinking the three letter stamp may be the date code, but not sure how to decipher it.

 

[Bendyha]

One would normally expect to see a second 3 number code as the date key, as well as a 312 for Sylvania, then I could help you out, but the letter code like you have, I have also seen, but can't find a decipher explanation for.

Also, I have read that they had a colour code;
Yellow - Retail consumer tubes
Red - Distributor
Green - Military
... but I can't verify if that is correct.

 

[tubedude]

I have several pairs of these and they are favorites.

 

[SnidelyWhiplash]

Great tubes.

 

[Bendyha]

Anyone have any info on Sylvania tube date coeds? Trying to identify the age of this one. There are two possible references: 'DEW', or 'ka'. I'm thinking the three letter stamp may be the date code, but not sure how to decipher it.

I have separate date code lists for tubes from Western Electric, Phillips, RCA and GE, and there are similarities between some of these and the Sylvania xx, xxx letter code, but without a factory copy of what they mean, one would have to gather hundreds of tubes and know the model release dates of history of build variations to be able to even start guessing what they really signify.
The letters can partly refer to the place of production; which factory. They can also be a reference to a batch unit, so that problems can be traced back. Maybe even a consignment batch made for a certain wholesaler-with count tally. And of course, they can refer to the date of production. Sadly, not much information seems to be available about Sylvania markings, other than that the 3 number system seems to be a YWW series, as others also used.