[AMRadio] RE: Source Date Codes for Electronic Products

Bob WB5YYX wb5yyx at uphi.net
Wed Jun 1 06:31:04 EDT 2005

To All-

I wanted to share an article I have recently written for the New Mexico
Radio Collectors Club in Albuquerque, New Mexico. Since we are
collectively radio amateurs, some antique radio and classic amateur
radio equipment enthusiasts, this may be helpful to you. Anyway enjoy
the information below and your comments are certainly welcomed.


Unraveling The Mystery of Source Date Codes


How One Can More Precisely Determine an Antique Radio's Age

By Bob Scupp WB5YYX

We obtain a new find antique radio and wish to know how old is it. What
is the manufacturing date? One can look at any collector's guide and get
the date production started. But how long was this model/chassis
manufactured? Can we determine somehow more precisely the year is was
produced? The answers to all of the previous questions are YES, YES and
YES! Starting during the 1940's electronic component manufacturers begin
printing Source Date Codes on their parts. Over the years they have
grown from 5 digits to 6,7 and 8. The first three or four numbers are
the manufacturer code (which company made this part). The last four
digits tell us the precise week and year the component was manufactured.
Is this helpful in determining an antique radio's age? You bet it does!
Let's take a better look at how it works.

I recently purchased some items at the Albuquerque Tailgate Swapfest on
April 23. One of them was an Emerson model G-1705a Lifetimer II AM/Clock
radio. It was not listed in my collector's guide to tell me the original
production starting year. I queried the AWA and Nostalgic Air Internet
message forums and asked if anyone could tell me the first production
year. I also requested a copy of the schematic and parts list. One
person answered and told me it was in Sams 615-6 issued February, 1963.
Therefore the first year of production for this model was 1962. But how
many years did Emerson manufacture this model number? In the scheme of
things what specific year was the one I had made in? Was this asking too
much? Apparently not. Another who responded gave me a hyperlink to
research Source Date Codes on electronic components. It was there that
it became clear to me how to unravel the mystery of Source Date Codes.

The first three or four digits in the SDC tell who the manufacturer was.
For example, any electronic component beginning with 106 is
Allen-Bradley. A component beginning with 137 is CTS Chicago Telephone
Supply. CTS was a major electronic component manufacturer and
sub-contractor for many other companies including TRW. I remember while
working at Electronic Parts Company in Albuquerque our line of TRW
products. Many of their resistor products, such as trimmer
potentiometers and variable potentiometers had CTS stamped on them. The
stamped part number began with 137! Of course TRW had their own part
number as well.

I noticed on the Emerson G-1705a that the tone control had a 1376404
number series stamped on it's back. The 137 is the code for the
manufacturer CTS (Chicago Telephone Supply). The 6404 is the code for
manufacturing date of the fourth week of 1964. Since it would be highly
unlikely that Emerson would have stocked parts for a year, I determined
it's production during the year 1964! The speaker had a part number of
180263, but it turned our to be Emerson's part number not the SDC. By
the way, the speaker according to Sams 615-6 was manufactured by Quam.

Can this SDC system be used elsewhere? ABSOLUTELY YES! These electronic
components are common to many other electronic devices such as guitar
amplifiers, TV's, etc. The website on the Internet for reading these SDC
's is http://www.provide.net/~cfh/pots.html. Enjoy the ability to date
electronic products through the Source Date Code system! I will
follow-up this article with more Source Date Code research as it becomes
available to me.

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