Q: Difference between grey glass and clear glass GEC KT66??

[Randy Payne]

Question:
Anybody know the difference between grey and clear glass Genalex
KT66's?? I've seen both types. Is one older than the other, or made in a
different factory?

Randy

[retr...@bigpond.com]

In article <38C873...@mailbag.com>,

Dear Randy

The grey glass are older production, the clear glass are newer
production. Everything else is identical, same glass shape, same
internal construction, same specs etc. I have some pics, old adverts and
specs at http://albums.photopoint.com/j/AlbumIndex?u=149682&a=1116335

I don't know when production changed from grey to clear glass. My guess
is sometime late 1960's. GEC used two date codes: the number code is
YYWW, but I don't know how to interpret letter code, I assume it is
Year/Month because I don't have any with the second letter past L (A-L
is twelve letters/months)

Anyway, here's the codes of a few KT66 I have here:
8303 Clear glass
7749 Clear glass
7620 Clear glass
UC Clear glass
YL Clear glass
PB Grey glass
RH Grey glass
LL Grey glass
PJ grey glass

Anyone shed any light on the two digit letter date code used by GEC?

Note also that GEC sold KT66 in different markets under a number of
different names, including GEC, Marconi, Emitron, Osram, Genelex.

AFAIK, Genelex name was only used in USA, perhaps to avoid GEC being
mistaken for GE. In the 1950's, GEC actually ran adverts in british
magazines advising that the KT66 sold in the USA was made in England and
sold locally as Osram! See 1952 advert at
http://albums.photopoint.com/j/ViewPhoto?u=149682&a=1116335&p=13893615

Hope this helps!
.....................................

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