Electronic devices (including transistors) are often stamped with
a code number to identify their origin and date of manufacture. This was
especially true of the 1950's which is the decade of most concern to early
transistor collectors. Many manufacturers belonged to a trade organization
which was originally called the RMA (Radio Manufacturer's Association).
This subsequently became RETMA (Radio Electronics & Television Manufacturers
Association) and finally the EIA (Electronic Industries Association). The
information presented below was obtained through various Internet resources,
personal contacts, and first hand observation of individual components.
Although the code was not an offical standardized format, a little
deciphering will generally yield some interesting information. The numbers
which follow are believed to be correct for the approximate period from
the 1940's through the 1960's. Many manufacturers also stamped OEM (Original
Equipment Manufacturer) part numbers above or below the RETMA code. In
some cases part makers or their customers elected not to include the codes,
so not all parts have them.
The codes generally follow the format of the following example:
980751In this case the translation is as follows... 980 is the RETMA code for Texas Instruments. 7 is the last digit of the year 1957. 51 is the next to the last week of December. NOTE: single digit date codes were used almost exclusively during the 1950's and two digit date codes became common in 1960 and later. There are exceptions however. Western Electric sometimes used two digit date codes in the 1950's and some manufacturers used single digit date codes in the 1960's.
^^------- week of year (01 through 52)
^--------- last digit of year (0 through 9)
^^^---------- manufacturers identification code (see tables below)
It helps a great deal to have other information which will help identify the period of the piece in question. You also have to simply ask yourself if the date code makes sense. For instance in the previous example the 7 might represent 1947... but the transistor wasn't invented until 1948. It might also be 1967 but TI was unlikely to have been making oval shaped metal cased transistors at that time. Historic knowledge is the key to correctly interpreting the date portion of the code.
TI commonly placed the RETMA codes on it own branded products while others (such as RCA) did not. The RCA code of 274 does show up on transistors which they branded for Emerson to use in their radios. This brings up another point... early RCA transistor date codes (typically 1950's) are usually different. They appear as a two digit code, seperate from the other labeling information. They consist of a number and a letter. The number represents the last digit of the year and the letter represents the month and ranges from A (January) through L (December). Although this may all sound too complex to figure out, but after a bit of practice you will become familiar with the system and confident about your identifications.
Here are some RETMA Code Lists for: Tubes/Transistors, Capacitors,
Transformers,
Potentiometers & Resistors, Speakers, Other Manufacturers
Tubes/Transistors Code
---------------------------------- ----
Amperex (USA) 111
Bendix 125
DuMont 158
Motorola 185
General Electric Co (USA) 188
Hytron (CBS-Hytron) 210
Philco 260
RCA (Radio Corp of America) 274
Raytheon 280
Sylvania (Hygrade Sylvania Corp) 312
Tung-Sol 322
Western Electric 336
Westinghouse 337
Zenith Radio Corp (CRT's) 343
Delco 466
RDR (Radio Development & Research) 924
Texas Instruments 980
Capacitors Code
------------------------------ ----
Aerovox Corp 102
American Condensor 109
Centralab 134
Chicago Condensor 135
Aerovox Hi-Q Division 163
John E Fast 178
General Electric 188
Mallory 235
Micamold 240
Millen 242
Radio Condensor Company 273
Solar 296
Sprague 303
Gudeman 438
Good-All 446
Barker & Wiiliamson 461
Pyramid 472
United Condensor 516
Electrical Utilities Corp 569
Illinois Capacitor (Condensor) 616
American Radionic 648
Sangamo 658
Ajax 705
Standard Condensor 710
RMC (Radio Materials Corp) 732
Condensor Manufacturers 885
Transformers & Coils Code
------------------------------ ----
Stancor (Chicago-Standard) 138
Coil Engineering 141
Ensign Coil 172
Freed 183
General Radio 194
Jefferson Electric 218
Thordarsen-Meissner 238
Merit Coil & Transformer 239
Standard Coil 305
Essex (Transformer Division) 352
New York Transformer 366
Altec Lansing-Peerless 391
Foster Transformer 394
General Transformer 412
United Transformer Corp (UTC) 418
Radio-Television Products Corp 489
Empire Coil 452
Caledonia 503
Triwec Transformer 524
Midwest Coil & Transformer 549
Standard Winding Co 550
F & V Coil Winding 572
Woodward-Schumacher 606
Central Coil 637
Electrical Windings 682
Grand Transformers 757
Forest Electric 773
Ogden Coil & Transformer 776
Triad 830
Better Coil & Transformer 831
Acro Products (Acrosound) 878
Mohawk 883
American Transformer 892
Tresco 897
Coilcraft 906
Aerocoil 908
Acme Coil & Transformer 928
Magnetic Coil Mfring 933
Northlake 1005
Pacific 1052
Resistor & Potentiometers Code
--------------------------------- ----
Allen-Bradley 106
Centralab 134
CTS (Chicago Telephone Supply) 137
Clarostat 140
Erie 173
IRC (International Resistance Co) 214
Mallory 235
Muter 244
Ohmite 251
Speer 300
Stackpole 304
Ward Leonard 532
Milwaukee Resistor 722
Dale 816
Atlas 932
Speakers Code
------------------------------------- ----
CTS (Chicago Telephone Supply) 137
Jensen 220
Magnavox 232
DuKane (Operadio Corp) 252
Quam (Quam-Nichols) 270
Rola 285
Utah 328
Western Electric 336
Altec Lansing Corp 391
North American Philips (Norelco) 423
Oxford 465
Waldom Electronics 555
Electro-Voice 649
Russell Speaker Co 748
Quincy Speaker Mfr Corp 767
Klipsch 843
University 847
Oaktron 934
OTHER COMMONLY SEEN MANUFACTURERSThat's it! Good luck with identifying your mysteries.
Company Product Code
---------------------- ------------------------- ----
Admiral Corp TV's, Radios 101
Cinch Sockets, connectors 139
Crosley Radios 152
General Radio Test Equip 194
Hallicrafters Ham & SW gear 199
E F Johnson Sockets, ham xcvrs 222
Magnavox Radios & TV's 232
Arvin Sears radios & TV's 248
Packard Bell TV's radios computers 254
Philco Radios & TV's 260
Philmore Hardware 262
Emerson Radios & TV's 277
Zenith Radios & TV's 343
Heath Electronic kits 416
Muntz Cheap TV's 772
Sonotone Phono cartridges 787
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