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Old 23rd June 2003, 05:16 PM   #1
EC8010 is offline EC8010  United Kingdom
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Default GEC date codes

Does anyone know how to crack the GEC date codes? I have reason to believe that "H" is before 1954, "L" before 1955, and "M" before 1957, and can contruct a table using those assumptions that might be right, but does anyone know the definitive answer?
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Old 23rd June 2003, 09:14 PM   #2
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Hi,

Oh, dear...wish I could help you out on that one.

None of my books mention that manufacturers' dating code...Philips and associates, yes..but GEC?

Aren't there any company archives?
Maybe radio collectors or Hams could help you out...

Cheers and good luck,
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Old 23rd June 2003, 10:04 PM   #3
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Default GEC codes

Does this look correct ? This is what I've got written on the workshop wall

A = 1945
B = 1946
C = 1947
D = 1948
E = 1949
F = 1950
G = 1951...etc
L = 1955...etc
R = 1960...etc
Z = 1968



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Old 23rd June 2003, 10:34 PM   #4
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Default Eureka?

Yes. That's exactly what I've worked out! I worked out my codes by having some valves with BBC acceptance dates on them, but I had to do a few nudges to make them fit. I enabled this by assuming that the Beeb (mighty corporation although it is) could buy and accept valves a year or two after manufacture, they couldn't do so before...

So, my question is, where did your decoding come from? Did you do the same as me, or did you have a more concrete source?
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Old 23rd June 2003, 10:41 PM   #5
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Default Codes

I found them on the web somewhere with a fairly good list of factory codes such as KB/T , KB/F etc , if I find the URL I'll post it

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Old 23rd June 2003, 10:48 PM   #6
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Default Brilliant!

So in that case, there's a good chance that the following is correct:

A 45
B 46
C 47
D 48
E 49
F 50
G 51
H 52
J 53
K 54
L 55
M 56
N 57
P 58
Q 59
R 60
S 61
T 62
U 63
V 64
W 65
X 66
Y 67
Z 68

I've not seen a GEC valve stamped 69, but I have one stamped 70.

Edit: Even better, this suggests that it was between 1961 and 1962 that GEC abandoned "smoked" in favour of "clear" glass KT66.
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