Marked: "Portafone / R1926". In the U.S. Patent Office, Lowell and Dunmore Exhibit No. 57. Believed to be the second Portaphone receiver. Unit is a six-tube tuned radio frequency receiver employing 215A "peanut" tubes. Case is actually a leather suitcase with a diaphragm-driven speaker horn and a coil antenna mounted in the top lid. Two 1.5 volt dry cells are strapped into the bottom of the case to provide filament voltages. An external plate battery was apparently used. The loudspeaker horn opens through an aperture in the cover of the leather case. This portable self-contained receiver was constructed by P.D. Lowell & F.W. Dunmore before the middle of 1921, and was demonstrated to visitors at the Bureau of Standards Radio Laboratory by Richard S. Ould, an electrical engineer who testified as a witness in the patent office Interference proceedings. An earlier model of the "portafone" was demonstrated before Alexander Graham Bell in May of 1921, and received radiotelephone broadcasts form station NSF in Anacostia. Reference: In the U.S. Patent Office" "Record and Testimony on Behalf of Lowell and Dunmore" (1928), page 503.
A tombstone-style radio receiver with "Standard Broadcast" (55 thru 180 KHz) and "Short Wave" (1.8 thru 6 MHz) reception. Wooden cabinet with chassis and speaker installed. Open back. Power cord is not original to the piece.
Broadcast radio grew into a major industry in the decade following the First World War as inventors refined the technology and entrepreneurs established supporting companies. By the 1930s, so many people wanted radio that the Great Depression slowed but could not stop the industry’s growth. Radio engineering became an attractive field for people interested in advanced technology and research laboratories like that operated by the Radio Corporation of America (RCA) pushed advances in components and circuit designs.
Materials research also affected radio, as seen in the plastic casing of this Emerson radio receiver from about 1937. The so-called tombstone design was popular in the 1920s but the receivers typically were made of wood. Aside from being flammable, wood cases could warp and split, and the finishes scratched and stained easily. This radio’s case, made with a plastic called catalin developed by the American Catalin Corporation in the late 1920s, resisted heat and incidental damage like water stains. Available in a variety of colors and designs, catalin radios remain popular with collectors.
Before 1954, so-called portable radio receivers used vacuum tubes to receive and amplify signals. The large batteries needed to power most tubes made radios large and heavy. Receivers built with subminiature tubes existed but were expensive. The invention of transistors in 1947 allowed engineers to design radios that could fit in a large pocket and such radios were first sold in late 1954. This RCA receiver from 1956 used 8 transistors and ordinary flashlight batteries. Though too large for a pocket, this radio was much easier to carry and more reliable than tube-based radios.
This Radio Data System (RDS) demonstration car radio was used in a 1995 ceremony on Capitol Hill marking the establishment of the 100th RDS-capable broadcast station, WKYS-FM in Washington, DC. RDS technology consisted of an inaudible text data stream transmitted from specially-equipped FM stations. The data included artist identification, community-service bulletins and traffic information. The demonstration receiver also includes a cassette tape deck with Dolby noise reduction. Engineer Ray Dolby designed a “sound compander” in the mid-1960s to improve audio output quality of recordings while working at Ampex and later founded a company to improve this technique.
The Scott model 2560 Casseiver combined an AM/FM stereo receiver with a cassette tape deck. Scott, a manufacturer of high-end radio receivers, adopted the cassette format invented by Philips in 1962. Philip’s cassette was one of several on the market. After its introduction in their Norelco line, the company offered free licences to other manufacturers who adopted the format. The original price on this Scott Casseiver was about $300, about $1700 in 2012 dollars.