Melville Eastham was one of the three founders of the Clapp, Eddy and Eastham Co. of Boston - manufacturers of X-ray coils which were also used in spark transmitters.  After Eddy left in 1908 the Clapp-Eastham Co. expanded into other wireless equipment.  Clapp sold out in 1910 and the company moved to Cambridge, MA.

In 1915 Eastham and four other investors founded the General Radio Company in Cambridge to manufacture radio measuring instruments and parts, and he sold his interest in Clapp-Eastham in 1917.  During the teens GR made mostly transmitting and receiving components, as well as a few complete receiving sets.  During the First World War the company's business greatly increased.  One of their products - a precision variable condenser - was used by Major Edwin H. Armstrong to tune his first superheterodyne receiver.

After the war GR increased their focus on the development of precision measuring instruments.  When the radio boom began in the early 1920s radio manufacturers turned to GR for the instruments needed to design and manufacture radio receivers, and by 1924 GR began its decades of dominance of the high-end instrument market.

During the '20s and '30s GR introduced a host of unique instruments, including the first commercially available oscilloscope.  Two '30s products found major uses during World War Two - the Variac variable autotransformer and the Strobotac - the first commercial strobe light.  During the cold war years GR continued to develop new instruments and to expand.  In the 1950s GR built a new manufacturing plant in West Concord, MA, and eventually consolidated operations there, closing the Cambridge plant.  The company later moved to Lexington, MA, where they continued in business as GenRad Corporation, and still later moved to Westford, MA.

In 2000 IET Labs in Westbury, NY acquired the GenRad standards, decade box, audio and strobe product lines, and continues to support those lines with sales, and with service and calibration at their Newton, MA facility.  GenRad Didibridge intruments are still manufactured, now under the Quadtech brand.  The rest of GenRad was purchased by Teradyne in 2001 and was later completely merged into Teradyne.  Some GR and GenRad products are still supported by other companies.

If you would like to learn more about GR's history I suggest that you read Arthur E. Theissen, A History of the General Radio Company (West Concord, MA: General Radio Co., 1965), now online in PDF format on the IET Labs site.

For each of the GR instruments described on this site I have listed the prices shown in the GR catalogs in my collection.  Catalog O (Jun-1956) and Catalog T (Feb-1968) are online at the BoatAnchor Manual Archive.