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Help with Mullard CV4004 Date code

69.112.140.55

Posted on March 4, 2017 at 14:38:49
oldngrumpy
Audiophile

Posts: 13
Joined: August 12, 2016
How do I figure out the exact year of manufacture for a Mullard CV4004 with box plates that has the following on it?

on one side near the bottom of the tube:
641
R3K3
I don't know what 641 means but I think the second line means Mitcham UK, 1963 or 73 or 83, November, 3rd Week. Also these alphanumerics don't rub or scrape off.

On the otherside of the tube in white paint that I can scrape off:
000-4004
CV4004
KQDD/K
84-18

Finally, there's an H etched into the very bottom of the tube where the pins stick out. It's right in the center of the circle formed by the pins.

Thank very much for your help.

OldnGrumpy




OldnGrumpy

 

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RE: Help with Mullard CV4004 Date code, posted on March 4, 2017 at 16:08:42
BBoterham
Audiophile

Posts: 16
Joined: June 21, 2016
The "KQDD/K" code was the very latest production/factory code used for Mullard CV4004 tubes.

These tubes where produced from the late 70s till mid 80s.

So yours are from week 3 of december (K) '83, and the CV4004 label was added in week 18 of 1984.

 

RE: Help with Mullard CV4004 Date code, posted on March 4, 2017 at 16:11:45
BBoterham
Audiophile

Posts: 16
Joined: June 21, 2016
Correction, it is November, as you mentioned already, my mistake.

 

RE: Help with Mullard CV4004 Date code, posted on March 4, 2017 at 18:44:29
FenderLover
Bored Member

Posts: 12659
Joined: July 31, 2007
Contributor
  Since:
May 17, 2009
"641"

64 = CV4004. 1 = first version.

 

RE: Help with Mullard CV4004 Date code, posted on March 6, 2017 at 10:41:00
oldngrumpy
Audiophile

Posts: 13
Joined: August 12, 2016
Thanks FenderLover.
OldnGrumpy

 

RE: Help with Mullard CV4004 Date code, posted on March 6, 2017 at 10:42:17
oldngrumpy
Audiophile

Posts: 13
Joined: August 12, 2016
Thank you both, FenderLover nad BBoterham. Much appreciated.
OldnGrumpy

 

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