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Nems-Clarke and Clarke Instruments

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Data sheets for 107-A, 120-D, 1037A, 1455, 1906, 1907, 2074, 2501A, 2801, DCA

My history of Nems-Clarke appeared in the June 2009 issue of Popular Communications (click to see).

Nems-Clarke has a long history. It started in 1951 when Clarke Instruments merged with National Electric Machine Shops (NEMS)

In 1951, Clarke Instruments was a small nine person design firm run by Allen S. Clarke. It rented space on the King Street side of the NEMS building at 919 Jessup Blair Drive in Silver Spring MD.

NEMS has a long history. The name was chosen in 1937 when the National Electric Supply Company incorporated. NESC was founded in February 1899 and manufactured radio parts from the very beginning of radio. Company archives contained photographs of transmitters produced for the Navy in 1909.

By 1951, NEMS was purely a production house. They took schematics and mechanical designs from other firms and built equipment. For example, some of RCA's early TV alignment generators were built by NEMS and shipped off to RCA for marketing. They owned the building at 919 Jessup Blair Drive. It housed machine shops, sheet metal fabrication, assembly and test facilities.

As Clarke Instruments was primarily a design firm and NEMS was an established production house, the merger quickly bore fruit. The name was officially changed to Nems-Clarke in January of 1955.

In the 1940s, Allen Clarke hired future CEI founder Ralph Grimm as his second employee. Grimm was a brilliant engineer who developed new and highly respected products for the firm. Grimm would become one of Clarke's favorite engineers.

Grimm designed the new Nems-Clarke line of telemetry and special purpose receivers starting with the Clarke Instruments 167. These products were widely used for ballistic missile telemetry by the Air Forces. Hundreds of late remodel receivers like the 1400 were installed at Cape Canaveral and across the Caribbean Sea along the Atlantic Missile Test Range.

The 2501 receiver and associated preamplifiers was used in the TRANSIT satellite program. For the DISCOVERER space program, Nems-Clarke developed the DCA series of diversity combiners. The 1455 receiver was developed for the CENTAUR booster rocket program.

Grimm also designed the Megalume electronic strobe lights and the 107-A and 120-D field strength meters that proved very popular in the broadcast industry.

In September 1957, Nems-Clarke was purchased by Vitro Corporation of America and the name was changed to Vitro Electronics. Vitro Corporation encompassed a variety of industries. Vitro subsidiaries designed, constructed and operated nuclear, chemical, metallurgy and defense facilities. They also produced uranium concentrate, thorium, rare earths and rare metals.

In the early Vitro Electronics years, the engineers at the Jessup Blair building developed the 1037A telemetry receiver. The 1037 was used for reception of all signals in the Mercury and Gemini manned space flight programs. These were hectic and exciting times. Engineers often worked erratic and late hours. The goal was to beat the Russians and adrenalin flowed freely. Many radios were modified at the last minute to gain "a dB here or a dB there." Some were shipped not matching the catalog and with circuits looking more like prototypes, but the end users were happy.

Vitro Electronics put two 1037s and a diversity combiner in one box and called it the 2074 (twice the 1037). This radio was developed for and successfully used in the Apollo manned space program. Because a space craft rotates relative to the earth, the phase of the signal is constantly changing. The 2074 had two full 1037 receivers right to the end of the IF stages. The diversity combiner was inserted before the detector. This yielded a 6 dB improvement over using two separate receivers and a post detection or audio stage diversity combiner.

The 2074 was used for much of the Apollo program. It was used to receive telemetry data from the Saturn V rocket.

Nems-Clarke made only a handful of surveillance receivers. The early units, the 1301, 1302 & 1306, were produced in significant quantities and examples pop up for sale regularly. They were bulky, at 5 rack units high, and had noisy forced air cooling for the RF stage - very unusual for a receiver. But the front panels have a graceful design with a certain charm.

The front end of these early radios used a 416B tube, which was a superior amplifier to the 7077 tubes used in later designs. The 416B was uncommon back then and now is quite rare. The cooling fan this tube required was problematic for some customers. Nems designed a version of the 1302 with a heat pipe and beryllium oxide cooling block to meet the specifications of a military contract. If you have one of these radios, I'd love to get more details and photographs.

The later 1906, 1907 and 2801 are smaller units that were acoustically quieter because they eliminated the squirrel cage blower required by the 416B. The 1906 and 1907 are relatively common. The 2801 appear to be much more rare. All three were purchased and modified for airborne use by LTV (see the G175 tech sheet for pictures and info on these modified units).

Nems-Clarke is significant in WJ history because several employees led by Ralph Grimm, left Vitro/ Nems-Clarke to form the new Communications Electronics Incorporated (CEI).

If you have any information, particularly early catalogs from Clarke Instruments, NESCO, NEMS, Nems-Clarke, Vitro, Defense Electronics, Inc or Astro Communications Labs, please contact me. I am always eager to fill in gaps in this fascinating history.

See also:

Nems-Clarke 1906 receiver - a fine high performance VHF surveillance receiver manufactured in the late 50s and early 60s.