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Calls Home from Auto by Short Wave
August 1935 Short Wave Craft

August 1935 Short Wave Craft

August 1935 Short Wave Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Short Wave Craft, published 1930 - 1936. All copyrights hereby acknowledged.

This could be one of the earliest reports of mobile communications between a private automobile and a home base station. Using a personally designed and installed 5−meter transceiver both at home and in his car, Mr. Wallace is able to talk to his 12-year-old son on the way from work. My guess is that in 1935 there were not too many traffic jams, even in Long Beach, California, so it is doubtful that was the cause for his announced expected later-than-normal arrival home. The article states the automobile power supply needed to produce 300 mA of current at 525 V, which is ~160 W per Ohm's law, which seems unlikely considering car batteries were 6 V at the time, and that would work out to ~26 A. My question is whether little Billy possessed a license permitting him to talk back to dear old dad from the home station? If not, it really doesn't matter at this point since there is probably some statute of limitations that absolves him from prosecution ;-)

RF Cafe visitor Dave H. wrote to offer the following additional information about the history of mobile radio communications. It is fairly extensive, so it is posted at the bottom of the page

Calls Home from Auto by Short Wave

Home station has a 1 kw. C.W - RF Cafe

The home station has a 1 kw C.W. and phone transmitter operating on 10, 20, 40, and 80 meters.

Don Wallace talking from car - RF Cafe

Don Wallace talking from car.

Don C. Wallace of Long Beach, California calls up his home daily on 5 meters, using the apparatus shown in the accompanying photos. His car is fitted with a 5−meter 2−way radio set, so that he can talk to his home and hear the folks when they talk to him. In the event that he is away on a trip 20 miles or so from home and finds that he will be home late, he can close a switch with his foot which will start his 5-meter transmitter going and he then calls his home. His 12−year−old son, Bill, stands watch everyday at 5:30 p.m.

By kicking the floor switch in the opposite direction, the 5−meter receiver is set into operation aboard the speeding auto and Don Wallace can then hear his son's voice and the "family news" of the day. Mr. Wallace tells us that the set on the car works as well at high speed as it does when standing still. The main parts of the transmitter are located under the hood of the car.

Twelve-volt storage batteries supply the primary current for the motor-generator, which delivers 525 volts with 300 M.A. The antenna on top of the car is a 5−foot vertical steel fishing rod; This is hinged so that if any object such as a tree should hit it while the car is speeding along, the pole will merely bend.

This antenna works against a 3−foot counterpoise which extends forward and down toward the hood. The entire 5-meter transmitter and receiver is relay−controlled, a foot-operated switch on the floor serving to operate all of the relays.

June 11, 2020 Note from Dave H.

I liked the article about Don Wallace and his car to home radio.

I knew that in Detroit, the police had attempted to have car to car transmissions. They were not overly successful however. They did implement a station to car, 1 way transmission.

I discovered the facts about the Detroit police radios while researching a paper that I wrote entitled: "SAW Filters : The Unsung Heroes of the Cell Phone Revolution"

Did you know that that the phone developed by Martin Cooper while at Motorola, circa 1973, had a filter board that measured 10 inches by about 1 inch? That would be a tad hard to fit into todays phones ! Microstrips and striplines also would be hard to fit into a cell phone ! And don't even talk about the the steep skirts that the filter requires to separate the transmit frequencies from the receive frequencies.

1st Detroit Police Radio - RF CafeHere are a few links to articles mostly about government, i.e. police, getting the technology early (along with Mr Wallace).

City of Irvine: History of Police Communications

The Origin of Two-Way Police Radio Communication

One-Way Police Radio Communication, 1928

Cellphone Development Timeline

How Detroit Police Reinvented the Wheel


Dave H. 



Posted June 10, 2020
(updated from original post on 4/8/2015)


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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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