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History of the manufacturer  

Sargent, E.M., Co.; Oakland CA

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Name: Sargent, E.M., Co.; Oakland CA    (USA)  
alternative name:
E.M. Sargent Co
Abbreviation: sargent
Products: Model types

E.M. Sargent Co.; 212-9 Street, Oakland, California: Brand Monarch. IN 1926 E.M. Sargent designed the "Infradyne Circuit" to avoid a lawsuit for making Superheterodynes. At least from 1933 to 1940 E.M. Sargent Co. made typical short wave communication receivers, also used by radio amateurs (HAM-radios).

In 1926 E.M. Sargent designed the "Infradyne Circuit" as a way to circumvent the RCA-Westinghouse held Superheterodyne patent and avoid an inevitable lawsuit. During the 1920s, no other company but RCA could legally sell superhets - or then "cross-licensed" companies, i.e. GE or Westinghouse. Kits could sometimes avoid legal problems. The Infradyne was originally sold only as a kit and by carefully avoiding the term "Superheterodyne", EM. Sargent Co. kept everything legal. A few companies took their chances with legalities and sold completed Infradyne kits, such as the Remloc Radio Co.

The Infradyne circuit uses the sum of the incoming signal and the second harmonic of the local oscillator resulting in an IF frequency of 3500kc. Since the sum is used, the local oscillator frequency must be reduced as the incoming signal frequency is increased so the IF will remain at 3500 kc. Bruce McCalley wrote: "The Infradyne Receiver Introduced in the August 1926 issue of Radio, and was featured for several issues after that. The Infradyne was one of the more unusual designs of the early days of radio. In the early days of radio there were a good number of odd-ball designs introduced. Some of these were to enable better performance, some were to save on the number of tubes required, and some seem to defy reason. The Infradyne, to this writer, seems to fit the last of these categories." ... "The IF amplifier, called the "Infradyne Amplifier" used three '99 tubes on a separate chassis. It was manufactured by Remler, a division of Gray and Danielson Mfg. Co, San Francisco, California." By the way: Remler Company, Limited, was founded in 1918 and was in business until 1988

Later Sargent has built normal superhets, for instance model 11.MA and some others - most often commercial double conversion sets.

The infradyne circuit was not really integrated in commercial production and within months it was no topic anymore. Before some adds in the journal "Radio magazine" from different makers stated that their set is suitable for the Infradyne. The term has a "new life" in very modern technique since about 1990 - Publication: "Katsushi Iwashita, et al., Chromatic Dispersion Compensation in Coherent Optical Communications, Journal of Lightwave Technology, vol. 8, No, 3, Mar. 1990, pp. 367-375. Chris Cho-Pin Li, et al., Comparison of Coded and Uncoded QPSK Intradyne and Heterodyne Receivers, IEEE, 1993 pp. 1891-1895."

The beginning - and end:
Sargent, an old shipboard radio operator, started E.M. Sargent Co. in his home in 1924. It is not known what they did until the production of their communication receivers in 1933. A couple of early receivers, the 'Long-Distance De Luxe' and the SW201 were produced in 1930, 1931 by an affiliate company, the Radio Constructors Co.
In 1934 the company moved to its definitive address, at 212 Ninth St., where they operated until the production of their last receiver, in 1940.
In 1948 Sargent sold his stock to L.C. Rayment, who formed with his son the Sargent-Rayment Co., to produce hi-fi equipment.
E.M. Sargent died in 1948 at the age of 56.

Some models:
Country Year Name 1st Tube Notes
USA  36 10 Monarch 6D6  Bc and 3 to 4 SW bands up to 20 Mc. Plug-in coils for wave band change. 
USA  25 SLF6   Three dials (primary tuning control knobs). 
USA  36/37 21MA   Covers 80 kHz - 30 MHz in 7 bands, BFO, regenerative 1st RF stage. 
USA  36/37 21AA 6K7  Covers 0,55 - 30 MHz in 5 bands, BFO, regenerative 1st RF stage using separate regeneratio... 
USA  36 11-MA 6D6  There are 3 different models Serie 11. this is the 11-MA. The model 11-MA has 7 or 8 sh... 
USA  40 WAC-44 6K7  The model WAC-44 receives 5 bands - from .54 to 31 MHz. IF: 456 kHz, Crystal Filter, 10 tu... 
USA  30 Long-Distance De Luxe   This receiver was actually built by a Sargent affiliate company, Radio Constructors Co. 
USA  31 Amateur Special SW201   1.5 to 30MHz; band switch and bandspread; pentode push-pull AF output. AC, DC, battery mod... 
USA  34/35 8-34 57  Coverage: 0.55 to 21MHz in four bands. Two IF stages, BFO; three wire antenna in, bal/unba... 
USA  34/35 Marine 8-34 57  Coverage: 0.2 to 20MHz in four bands. Two IF stages, BFO; three wire antenna in, bal/unbal... 
USA  34 Europa Model 8-34   Five bands, covering from 0.2 to 20MHz. Variant of the standard 8-34 model. 
USA  38–40 51-AK 6F7  Five bands, 0.54 to 31MHz. RF and mixer panel trimmers. Triode section of 6F7 used as feed...