GEC KT88 Date manufactured and where?

[Richard[_11_]]

Found two GEC KT88 tubes in the attic, (not boxed).

In the rectangle, below the designation "KT88" is, I think, a date and
manufacture code of: "RB Z"

Anyone know when these were manufactured?

They are similar looking to:

http://www.natubes.com/data/images/product/large_517.gif

[kheper]

On Aug 31, 7:52*pm, Richard > wrote:
> Found two GEC KT88 tubes in the attic, (not boxed).
>
> In the rectangle, below the designation "KT88" is, I think, a date and
> manufacture code of: "RB *Z"
>
> Anyone know when these were manufactured?
>
> They are similar looking to:
>
> http://www.natubes.com/data/images/product/large_517.gif

Don't take this as gospel. I am assuming that what you are referring
to is the CV number.

RB = Ferranti, Dundee

Z might be a test specification.

http://www.tubecollector.org/cv-valves.htm

[jh[_2_]]

kheper schrieb:
> On Aug 31, 7:52 pm, Richard > wrote:
>> Found two GEC KT88 tubes in the attic, (not boxed).
>>
>> In the rectangle, below the designation "KT88" is, I think, a date and
>> manufacture code of: "RB Z"
>>
>> Anyone know when these were manufactured?
>>
>> They are similar looking to:
>>
>> http://www.natubes.com/data/images/product/large_517.gif
>
> Don't take this as gospel. I am assuming that what you are referring
> to is the CV number.
>
> RB = Ferranti, Dundee
>
> Z might be a test specification.
>
> http://www.tubecollector.org/cv-valves.htm


according to this page - thanks for the link - it might also mean

MO Valve Company, Hammersmith

which would be very likely for a KT88.

RB might be the date code according to this source:
"Alternatively two letters were used. This was allowed up to January 1st
1965. In this scheme the first letter A = 1945 and so on, and the second
letter A=January and so on. Letters I and O were not used. Thus AA =
January 1945, NF = June 1957."

Feb 1960?

regards

Jochen

[Richard[_11_]]

On 01/09/2010 06:41, jh wrote:
> kheper schrieb:
>> On Aug 31, 7:52 pm, Richard > wrote:
>>> Found two GEC KT88 tubes in the attic, (not boxed).
>>>
>>> In the rectangle, below the designation "KT88" is, I think, a date and
>>> manufacture code of: "RB Z"
>>>
>>> Anyone know when these were manufactured?
>>>
>>> They are similar looking to:
>>>
>>> http://www.natubes.com/data/images/product/large_517.gif
>>
>> Don't take this as gospel. I am assuming that what you are referring
>> to is the CV number.
>>
>> RB = Ferranti, Dundee
>>
>> Z might be a test specification.
>>
>> http://www.tubecollector.org/cv-valves.htm
>
>
> according to this page - thanks for the link - it might also mean
>
> MO Valve Company, Hammersmith
>
> which would be very likely for a KT88.
>
> RB might be the date code according to this source:
> "Alternatively two letters were used. This was allowed up to January 1st
> 1965. In this scheme the first letter A = 1945 and so on, and the second
> letter A=January and so on. Letters I and O were not used. Thus AA =
> January 1945, NF = June 1957."
>
> Feb 1960?
>
> regards
>
> Jochen

Thanks. I think that is probably correct.

Made at Hammersmith February 1960.

Interesting discussion here on date codes:

http://forum.marstran.com/viewtopic.php?f=6&t=130

[kheper]

On Sep 1, 7:31*am, Richard > wrote:
> On 01/09/2010 06:41, jh wrote:
>
>
>
> > kheper schrieb:
> >> On Aug 31, 7:52 pm, Richard > wrote:
> >>> Found two GEC KT88 tubes in the attic, (not boxed).
>
> >>> In the rectangle, below the designation "KT88" is, I think, a date and
> >>> manufacture code of: "RB Z"
>
> >>> Anyone know when these were manufactured?
>
> >>> They are similar looking to:
>
> >>>http://www.natubes.com/data/images/product/large_517.gif
>
> >> Don't take this as gospel. I am assuming that what you are referring
> >> to is the CV number.
>
> >> RB = Ferranti, Dundee
>
> >> Z might be a test specification.
>
> >>http://www.tubecollector.org/cv-valves.htm
>
> > according to this page - thanks for the link - it might also mean
>
> > MO Valve Company, Hammersmith
>
> > which would be very likely for a KT88.
>
> > RB might be the date code according to this source:
> > "Alternatively two letters were used. This was allowed up to January 1st
> > 1965. In this scheme the first letter A = 1945 and so on, and the second
> > letter A=January and so on. Letters I and O were not used. Thus AA =
> > January 1945, NF = June 1957."
>
> > Feb 1960?
>
> > regards
>
> > Jochen
>
> Thanks. I think that is probably correct.
>
> Made at Hammersmith February 1960.
>
> Interesting discussion here on date codes:
>
> http://forum.marstran.com/viewtopic.php?f=6&t=130

Yeah, my error. I do not see how I missed that paragraph. Anyway, nice
KT88 tubes.