the drastic cost-cutting market of the 1960s and 1970s. The transmitter line was later sold to Continental Electronics, which continued to produce a number of Collins designs under its own nameplate before phasing them out in the 1980s. Shortwave transmitters Collins produced several shortwave transmitters to the commercial market. A "30" Series production catered to the growing need of state highway patrol agencies and Department of Commerce aviation needs. During World War II, Collins produced high-power transmitters for aircraft, notably the ART-13 equipped with automatic tuning circuits, which represented an important enhancement for airborne radio communications. After World War II, Collins supported both broadcast and the growing postwar amateur radio market. The United States Coast Guard Cutter USCGC Courier was employed as seagoing relay station for Voice of America programming using two Collins 207B-1 transmitters. Amateur radio transmitters included the 32V-1, -2, and -3, the KWS-1, and the rack-mounted KW-1. Receivers Around 1947, the company introduced their first amateur radio receiver, the 75A-1 (called the 75A). This set achieved excellent stability for the time due to high build quality and the use of a permeability tuned oscillator in its second conversion stage. It was one of the few double-conversion superheterodynes on the market, and covered only the amateur bands. With the experience gained in the design of the 75A-1, Collins released the 51J-1 receiver, a general-coverage HF set covering to. It was produced in somewhat updated versions (51J-2, 51J-3, 51J-4) for about a decade. It was known as the R-388 and was used in multiple receiver diversity radioteletype installations. The 75A amateur line was updated throughout the early , finishing with the 75A-4, which was released in 1955. The Collins mechanical filter was introduced to consumers in the 75A-3, and the 75A-4 was one of the first receivers marketed specifically as a single sideband receiver. Around 1950, Collins began designing the R-390 () for the US military. This was intended to be a receiver of the highest performance available, with the ruggedness and serviceability required for military duty. It featured direct mechanical digital frequency readout. The set is composed of several modules for easy field repair—a bad module could simply be swapped out and repaired later, or junked. Sets built during the original 1951 contract cost the government about () each, and around 16,000 were produced. Concurrently, Collins developed the R-389, a long-wave version with fewer than 1000 made. The