The Hammarlund Manufacturing Company, known to most as simply "Hammarlund", was one of the major manufacturers of shortwave and Amateur Radio equipment in the United States. Along with Hallicrafters, and the National Radio Company, it was once the third member of the “big three” communications companies.

Oscar Hammarlund founded the company in 1910, in New York City. He had been an engineer for the Ericcson Company in Stockholm, and arrived in the United States in 1882. Later, he worked as a factory superintendent for Western Electric, and left there to become involved in the development of the Teleautograph, a forerunner of the facsimile machine.

In the early 1920s, the company entered the radio business through an affiliate, Hammarlund-Roberts Company. Hammarlund-Roberts manufactured and marketed broadcast band receivers, while Hammarlund manufactured many of the parts for the receivers. Working closely with experimenters, the company quickly became known for its high quality tuning capacitors, coils, and precision dials. The Hammarlund-Roberts name was discontinued around 1932.

Hammarlund had the distinction of producing the first commercial superheterodyne communications receiver. This receiver, called the Comet, was introduced in late 1931 and was an immediate success. It was replaced in April 1932 by the Comet Pro, an improved version of the Comet. This receiver was an eight-tube marvel and was as successful as its predecessor. Professional listening post installations made great use of the Comet Pro, and it was used also on many major exploration expeditions. The receiver was also very popular with Amateur Radio operators. The Comet Pro was Hammarlund’s flagship model until late 1936.

THE SUPER PRO SERIES

Early in 1933, Hammarlund engineers began work on what the company hoped would be the ultimate communications receiver. It would be a general coverage receiver; and it would have the same attention to detail as was found in many of the National Radio Company's products. Designed for amateur and commercial operation alike, it would be uncompromising in its design.

This receiver was originally to be called the Comet Super Pro, but when released in mid-1936, it was called simply the Super Pro. While not quite the ‘ultimate receiver’, the Super Pro was the first of a classic receiver line. Unlike many receiver manufacturers, Hammarlund itself made many of the components of the receiver. Among those custom-built components were a twelve-section tuning capacitor, special intermediate-frequency transformers, and a low-loss band-changing switch. The Super Pro series was continuously improved over the years and, in one form or another, in production until 1973. Its descendants include the SP-100 (1937), the SP-200 (1939), the SP-400 (1946), and the most famous of the line, the SP-600 (1950).

The SP-600 was widely accepted by both military and commercial users. It went through many variations, differentiated by a suffix to the model number. Some of those variations were:

  • the JX-4 model, with outputs for diversity reception. Sold to the military as model R-320A.
  • the JX-12 model, the standard off-the-shelf model SP-600. Sold to the military as model R-274.
  • the JLX-15 model, with tuning range of 15-600 kilohertz (as opposed to the normal range, .54-54 Megahertz). Intended for long-wave and aircraft beacon use.
  • the JX-21 model, the last commercial release, in 1972; available until late 1973. This model was updated for single-sideband reception.
  • the JL-34 model, with a restricted tuning range, as per Central Intelligence Agency requirements.
  • the JX-36 model, with an audio input jack. Built for the Federal Bureau of Investigation.

THE HQ SERIES

Up to 1937, Hammarlund had intended that their only receiver produced to date, the Super Pro, would be a top-of-the-line model. However, the company began to feel pressure from other manufacturers who were producing a more complete line of receivers across the price spectrum. Responding to the situation, Hammarlund began work on a receiver that would compete not only in performance, but in pricing as well. The result of this effort was the model HQ-120, introduced in 1938. There was little, if any, compromise of Hammarlund quality in this lower-priced receiver. It featured excellent performance, a large bandspread dial, and an optional crystal filter was available. The HQ-120 was as successful as the Super Pro, and was the progenitor of Hammarlund's second series of popular receivers:

  • Model HQ-129X (1945), the direct successor to the HQ-120. It featured updated circuitry and improved metal vacuum tubes, and originally sold for $129.
  • Model HQ-140X (1953), first in the series to feature miniature tubes, and separate mixer and oscillator circuitry for improved stability.
  • Model HQ-150 (1956), an improved version of the HQ-140, adding a Q-multiplier filter circuit.
  • Model HQ-160 (1958), the first major improvement to the series. Features included a product detector for single-sideband reception, double superheterodyne conversion, and a T-notch filter circuit.
  • Models HQ-180 (1959) and HQ-180A (1963-72). These receivers were Hammarlund’s last major releases to use vacuum tubes. They were the most successful of the series and featured many improvements, including triple superheterodyne conversion, superior intermediate-frequency amplifiers, and a product detector for single-sideband operation. Unlike the SP-600, which was intended for military and commercial applications, the HQ-180 receivers were designed (and priced) for amateur and shortwave listening uses. Today, it is one of the most collectible of Hammarlund models.

Many of these models could be fitted with an optional clock accessory. In addition to providing the operator a convenient timepiece, the clock could turn the receiver on or off at preset times.

During World War II, Hammarlund, like many other manufacturers, converted to wartime production. The company was a minor player in the war effort; though its receivers found some application, it was more often Hammarlund parts that were used in military communications equipment.

Near the end of the war, in 1945, founder Oscar Hammarlund died. His son, Lloyd Hammarlund, assumed the operation of the company.

HAMMARLUND’S LATER YEARS

As with many other communications receiver manufacturers, Hammarlund encountered changing times in the 1960s. The industry was moving toward smaller receivers, and a shift to solid-state circuitry was underway. While the company's parts business remained successful (Hammarlund capacitors, for example, were still an industry standard), it was clearly time to rethink the receiver operation.

Hammarlund immediately began design work on two solid-state receivers. The HQ-215 (amateur band only coverage) and the HQ-225 (general coverage) were planned for release in the late 1960s. However, only the HQ-215 actually appeared on dealer shelves; the HQ-225 design was terminated early on for reasons unknown. The HQ-215 was finally released in 1967, to disappointing sales. Its performance was lackluster, and the radio had design flaws that were difficult to rectify. It was discontinued after a few years and Hammarlund withdrew from the receiver market. Only the HQ-180 series and the SP-600 remained in production, until 1973.

Hammarlund also made tentative excursions into the transmitter market with the HX-500 single-sideband model in 1960. It was a well-designed product, but did not sell well, perhaps due to its cost and over-sophistication. The company introduced a lower-cost model, the HX-50, in 1962. This model featured a simplified tuning system and crystal filters.

The company had, by this time, completed the transfer of all its operations to a new facility in Mars Hill, North Carolina. Starting in the late 1950s, Hammarlund had gone through a series of new owners. The capacitor and parts operation was sold to Cardwell Capacitor, and Pax Manufacturing Company of New Jersey purchased the remaining receiver operation. With that, the Hammarlund name passed from the scene and has not reappeared.


SOURCES

‘The Hammarlund Historian’. The Hammarlund Historian. 4 November 2002. <http://www.hammarlund.info/histpage.html> (25 December 2002)
Quaglieri, Al. "Hammarlund Comments".The Hollow State Newsletter. Summer 1986: Pages 2-4.
Moore, Raymond. Communications Receivers, Fourth Edition. La Belle, Florida: RSM Communications, 1997
Osterman, Fred. Shortwave Receivers Past and Present. Reynoldsburg, Ohio: Universal Radio Research, 1998

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