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Old 24th December 2003, 07:37 PM   #1
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Default Sylvania Chrome top 6SN7 tube

Can someone tell me the aprox age of the green lettered Sylvania chrome top tubes? They are slightly smaller in height tan the GE 6SN7 GTB tube.

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J
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Old 25th December 2003, 12:50 AM   #2
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Hi! I'm a new guy...

Most of military purpose Sylvania tubes (i.e. the Green Logo) were manufactured after 1980s.

The Green Logo tells you that it was made for military purpose (especially American).

If you see the tube carefully, you might be able to find a word "JAN". This word means 'American Military Purpose'
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Old 25th December 2003, 01:48 AM   #3
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Hi,

Any acid etched code on the tube, Joe?

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Old 25th December 2003, 02:36 AM   #4
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Hi Frank

Below the 6SN7 GTA it says A4B. On the base next to the shield it says 413 I can send picture if it helps.

Merry Christmas


J
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Old 25th December 2003, 06:33 AM   #5
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Hi,

Quote:
If you see the tube carefully, you might be able to find a word "JAN". This word means 'American Military Purpose'
It actually means: Joined Army and Navy.

Quote:
Below the 6SN7 GTA it says A4B. On the base next to the shield it says 413 I can send picture if it helps.
I'll try to look it up after that turkey's been digested....

Quote:
Merry Christmas
And to you all,
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Old 25th December 2003, 11:54 AM   #6
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Quote:
It actually means: Joined Army and Navy.
That poor guy. Next is the Marines, I suppose.

Actually it's "Joint" Army and Navy.

Enjoy the turkey!
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Old 25th December 2003, 11:59 AM   #7
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Looked the tubes over. No JAN, just Sylvania,the logo and 413 to the right of the logo.


Enjoy the turkey and take it easy on the wine.


J
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Old 26th December 2003, 01:45 PM   #8
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Hi,

This is what I've found so far:

"The gtb version of the 6sn7 increased the plate voltage from the gt's 300 volts to an impressive 450 volts (most audio circuits have a net 200 volt or less plate voltage) and added a "controlled-warmup" for series-string circuits. The date codes "c-k" and "d-k" are part of sylvania's mysterious coding system but it is estimated that the date of mfg was in the late fifties or early sixties. The plates are black and "t" shaped. The getter (located in the top) produces the ornate flashing and hence the name, "chrome dome". The base is the short intermediate (.6 inches) type."

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Old 26th December 2003, 02:09 PM   #9
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Hi,

Quote:
the logo and 413 to the right of the logo.
The 413 is the manufacturer EIA code.
I know North American Philips had # 423.

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Old 26th December 2003, 04:00 PM   #10
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Hi,

Quote:
The 413 is the manufacturer EIA code.
Hmmmm...Did some further research on that and am starting to have second thoughts about that...

Anyone else have a clue?

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