[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/p.../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/p.../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/p.../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/p.../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/p.../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.