The 74A4 and KWS-1 is an

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

receiver and transmitter pair made by the

Collins Radio Company Rockwell Collins was a multinational corporation headquartered in Cedar Rapids, Iowa, providing avionics and information technology systems and services to government agencies and aircraft manufacturers. It was formed when the Collins Radio Comp ...

Cedar Rapids, Iowa Cedar Rapids () is the second-largest city in Iowa, United States and is the county seat of Linn County, Iowa, Linn County. The city lies on both banks of the Cedar River (Iowa River), Cedar River, north of Iowa City, Iowa, Iowa City and north ...

that were introduced in 1955. They were designed to operate using the then new

single-sideband In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude m ...

(SSB) voice modulation as well as CW and AM modes. They were influential in popularizing SSB.

Debut

The KWS-1 transmitter along with the 75A-4 receiver, together, cost over $2500 when new (equivalent to over $20,000 in 2012 dollars). Collins products at the time were considered 'top of the line'. Ham radio enthusiasts nicknamed the pair the "

Gold Dust Twins The Gold Dust Twins, the trademark for Fairbank's Gold Dust washing powder products, appeared in printed media as early as 1892. "Goldie" and "Dusty", the original Gold Dust Twins, were often shown doing household chores together. In general us ...

", since they were unaffordable for most amateur radio enthusiasts when first introduced. Both radios used

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

s and employed Collins innovations including

mechanical filter A mechanical filter is a signal processing filter usually used in place of an electronic filter at radio frequencies. Its purpose is the same as that of a normal electronic filter: to pass a range of signal frequencies, but to block others. T ...

s and permeability tuned oscillators. The KWS-1 final amplifier use a pair of 4X150 power tubes and operated at a power input of one kilowatt, the maximum allowed under

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction ...

(FCC) regulations at the time. The transmitter appearance matched the receiver, but its high voltage power supply was packaged in a separate pedestal.

Persistent favor

In a 2006 review of the half-century-old 75A-4 Stu Cohen wrote "Performance under all but extremely crowded band conditions is still excellent, and a 75A-4 will hold its own against almost any receiver. Under less crowded band conditions, the performance is superb."

Footnotes

References

External links

* {{cite web , url=http://www.wa3key.com/kws1.html , title=Virtual Collins Radio Museum , website=wa3key.com Amateur radio receivers Amateur radio transmitters Products introduced in 1955