RCA Theremin Identification & Serial Numbers

Serial Number & Cabinet Number locations

Serial Number

A unique six digit serial number is stamped in one of two places on the brown metal chassis depending on whether the theremin was made by Westinghouse or General Electric subcontractors. Westinghouse serial numbers begin with 200 and are located in front of the UY-227 vacuum tube socket behind the taller coil form. GE serial numbers begin with 100 and are located in front of the middle UY-227 vacuum tube socket in very small numbers. The minuscule size of the GE number embossing and its apparent hand-stamped qualities can make it very difficult to read. Good lighting and magnification can help avoid errors. We require the submission of photographs of serial numbers to our registry.

If the theremin is a Westinghouse, it may be easier to read the serial number behind the tall coil if you slide the chassis board out partially. Remove the two screws that secure the outer ends of the board (if present), and note the short cables that connect the tall coils to the cabinet, which if not disconnected, will limit the distance you can slide the chassis board out. To avoid possible damage, do not slide the shelf more than needed to view the serial number; approximately two inches should be sufficient. Note that there are no stops to prevent dropping or tipping the shelf if it is drawn out too far.

Serial Number Characters

The RCA Theremin Registry has been greatly enriched and made more accurate by serial number photographs that have been submitted by each instrument owner. We sincerely appreciate the time and care you have taken to contribute. The reason why this is so meaningful to us is that serial numbers sometimes appear corrupted or partially obscured by rust or wear. Even well preserved examples can be corrupted in different ways, such as double or partial stamping, that make deciphering the correct serial number a difficult task. We note that while most stamped-embossed serial numbers are clearly legible, there are numerous examples of anomalies. Some examples of actual stamped serial numbers appear below, with double strikes and rotated characters. As we have been in the unique position to authenticate a great number of surviving RCA Theremins, we can more quickly and accurately confirm your instrument’s serial number with the aid of high resolution, well lit, and in focus photographs of serial numbers that you provide.

Cabinet Number

The cabinet number is located under the back doors of the cabinet. It is stamped into the wood on both doors. It should be between 1 and 500, but may be higher.

Differences between General Electric & Westinghouse Theremins

RCA subcontracted the manufacturing of the theremin to their two primary U.S. suppliers: General Electric, located in Schenectady, New York, and Westinghouse, located in Springfield, Massachusetts. GE built 300 Theremins, and Westinghouse made 200. Since they were made in different factories, there exist a few distinguishing features that make identifying the subcontractor easy. These are listed below.

It should be noted that only the chassis serial number is the most trusted proof of factory origin, since replacements and restorations over the years may have obscured some of the normal identifying features.

The chassis serial number will help us identify the RCA subcontractor as well as a particular theremin's sequence in the production. The cabinet number, which is stamped into the bottom of each door, is unrelated to the factory that produced the working parts of the instrument. When adding your theremin to the Registry, the chassis serial number is required.

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