Household Radio Sets In The 1920s

BY Z.H.

Powering the First Radios

• From 1920-1927, ALL radio sets containing vacuum tubes made for the consumer market ran on batteries, as AC (Alternating Current) amplifiers did not exist yet.

• The ONLY radio sets that did not need tubes or batteries during this time frame were “Crystal Sets”, which used a lead galena crystal. However, these radio sets could only use headphones.

• As a matter of fact, the vacuum tube sets required three different types of batteries. They required a 6 volt “A” battery supply, a 90-volt “B” battery supply, and a 4 1/2 volt “C” battery supply.

Early Radio Battery Chargers• In the 1920s, in areas that were wired for electricity one could

purchase a radio battery charger.

• The two most popular chargers were the General Electric Tungar charger and the Westinghouse Rectigon charger.

• These chargers required argon-filled “bulbs” in order to function.

• The Tungar name came from the phrase “Tungsten-Argon” while Rectigon came from “Rectifier-Argon”

• These chargers could really only be used on the “A” batteries.

• Unlike modern chargers, these did not shut off automatically, and if the battery was overcharged, it was a very serious fire hazard.

Tuning The 1920s Radios• One of the most popular types of radio receiver in the

1920s was the Tuned-Radio Frequency (or TRF type. (One Example is the “Lang Radio Series V” radio set of 1923.)

• These radios often had multiple dials (most often three) that ALL had to be tuned to get ONE station.

• Tuning such radios could take 5-10 minutes.

• Some TRF sets required a “regeneration control” which controlled the “reaction” between the vacuum tubes and radio signal.

1920s Horn Speakers• Until the late 1920s, ALL radios that were meant

for a loudspeaker used external “horn” or “funnel” shaped speakers.

• Two examples of these speakers would be the Thorola Junior and the Radio Magnavox.

• MOST of the amplification was mechanical, due to the contour of the horn. The workings were in the base of the horn.

The Antenna (Aerial) Setup in the 1920s

• The antenna (also called an “aerial”) on the 1920s sets was supposed to consist of thin cloth-wrapped “bell wire”

• The antenna had to be 75 to 150 feet long, but it could be wrapped around a picture frame or a similar object.

• In any area where there were other electrical or communication (i.e. telephone or telegraph) wires, the antenna must run at right angles from the other wires.

Grounding Apparatus• At this point in time, the radio sets also required

a ground wire, which was to be hooked up via a “grounding clamp” fastened to a water or steam pipe.

• One was strongly cautioned to avoid using natural gas pipes as a ground, to avoid the risk of explosion from the electrical discharge onto the pipe.

Early A.C. Radio Sets (1927)• In the Autumn of 1927, the first “AC Sets”, such as

the RCA (Radio Corporation of America) Radiola 17, went on the market.

• This sets did not require batteries, and could simply be plugged into the wall.

• AC radio sets required AC vacuum tubes.

• They had heavy transformers, or “battery eliminators” in them.

“Cone” Loudspeakers

• Also around 1927, external cone loudspeakers (which are what we still use today) were offered to go along with the new AC-powered radio sets.

• Two examples of early cone speakers would be the RCA Radiola 100-A loudspeaker, and the Type “E” Loudspeaker made by the Atwater Kent Company of Philadelphia, Pennsylvania.

Electro-Dynamic Radio Sets• Around 1929, radio sets designed for “Electro-Dynamic”

loudspeakers came out.

• Electro-Dynamic speakers used a special electromagnet, and therefore could get much louder than other cone speakers of the day.

• They required four wires, not two, that connected to the radio receiver.

• Only AC-powered sets could be electro-dynamic.

• If an electro-dynamic set was operated without the proper speaker connected, it would overheat and burn out.

“Screen-Grid” Radio Sets• Also around 1929, “Screen-Grid” (also known as

“Shield-Grid”) vacuum tubes were developed.

• These tubes were specially designed to filter out particular kinds of audible interference.

• New AC sets had to be specifically designed for the new screen-grid tubes.

• These radios had wires that one had to clip to a contact on the top of the receiver tubes.

Bibliography• 1.) Johnson, David and Betty. Guide to Old Radios-Pointers,

Pictures, and Prices (Second Edition) : Krause Publications, Iola, Wisconsin, 1989 (Renewed 1995). Print.

• 2.) RCA Radiola III Instruction Manual, author unknown, Copyright 1924.

• 3.) http://www.radiolaguy.com/Showcase/Radiola/Radiola17.htm “RCA Radiola 17”. Web, 20 October 2014.

• 4.) Wooten, Allen. http://wd4eui.com/AK46.html “1929 Atwater Kent Model 46 and Model F2 Loudspeaker”. Web., 20 October 2014.

• 5.) http://www.antiqueradiomuseum.org/metalcasedradios.htm “Metal Cased Radios”. Jim’s Antique Radio Museum. Web., 20 October 2014.

Photograph Credits

• All of the photographs in this presentation were taken by me, and all the objects in them are part of my personal collection, hence there is no reason to cite where they came from.