From rcsigur–(at)–m.com Tue Dec 17 15:46:25 CST 1996
Article: 20311 of rec.audio.tubes
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From: rcsigur–(at)–m.com (Richard Sigurdson)
Newsgroups: rec.audio.tubes
Subject: Re: tube manufacturer codes?
Date: Tue, 17 Dec 1996 20:23:26 GMT
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Gordon Trump wrote:

>Many years (25+) ago when I serviced consumer and pro audio and video gear,
>the tubes we bought for replacement use all had a 3-digit code on the side.
>”274″ was RCA and “312″ was Sylvania and “337″ was Zenith? This code
> Does anyone have a list of these codes? They ocasionally also
>appeared on other parts- like transformers, etc.
>–
>Gordon O. Trump Sales Engineer
>Red Rose Communications
>717.738.8441 voice 717.738.7030 fax

Gordon,

In the early 70′s I was a tech at a local Sylvania TV distributor and had a book
published by the EIA (trade association of domestic OEMs) which had a list of numbers
followed by the vendor. I wish I had a copy of that book today. The numbers you have
listed are correct.

Other OEMs are GE -188 , Westinghouse-337, Tung-Sol-322, Raytheon-280.
GE put 188 on tubes they made and labeled GE but RCA did not put 274 on RCA branded tubes,
but 274 was found on tubes they made for other OEMs including Sylvania and GE.

Zenith didn’t make their own receiving tubes but did have a CRT plant ( Rauland) and put
the Rauland number on those tubes. Sylvania made the majority of small tubes for Zenith,
and I believe they designed tubes for their specific needs.

Motorola, Admiral, and other smaller manufacturers bought tubes from who ever made tubes
that fit their specs. Those tubes had the set name (Motorola, etc,) labeled, along with
the EIA code stamped on the tube, along with a date code, such as 6812, meaning the tube
was made in 1968, 12th week.
Picture tube date codes were usually 2 years (color) or 1 year (b&w) from the date of
manufacture which indicated the end the warranty period.

With the majority of components for home entertainment product being made off-shore, most
of them don’t have EIA numbers. I have seen currently made CRTs with familiar 312 and 274
numbers on them though.

Richard Sigurdson
Sr. Eng. Tech. KMSP-TV/UPN9-Mpls/St. Paul
rcsigur–(at)–m.com