Category Archives: Radio history

1947 4-Tube Broadcast/Shortwave Receiver

1947MayPMSeventy-five years ago, this couple are pulling in a program on the shortwaves thanks to the 4-tube set described in the May 1947 issue of Popular Mechanics.

1947MayPM2It was actually the second in a series of “progressive” receivers. The circuit was entirely different from the radio shown in the previous month’s issue, but it used most of the same parts and had the same layout, using a slat-style wooden chassis to make construction (or re-construction) easy.

It covered 550 kHz to 16.6 MHz with three plug-in coils. It was said to be an excellent performer on the shortwave bands, and had enough audio to provide loudspeaker volume. No battery was needed, since it used one of the 6J5 tubes as a rectifier, and contained a filament transformer.

1947MayPM3



Merle Radio Company, Plainfield, NJ, 1952

1952MayRadioElecThe efficient workbench shown here is an auto radio work station of Merle Radio Company, Plainfield, NJ, as shown on the cover of Radio-Electronics, May 1952.

Service was handled in a drive-in shop, part of a 35 x 90 foot overall space for the business. The owner of the shop had recently branched out in the radio industry, having purchased the local FM station, WXNJ, and had an AM application pending.



1962 3M Aztec Kerosene Generator

1962MayRadioElecWe’ve previously reported that in the late 1950s, the Soviets led the free world not only in space, but also in kerosene powered radios. They produced a 7-tube set powered by kerosene, a thermocouple, and vibrator power supply.

But it turns out that the Americans were close on their heels, and were producing a superior product just a few years later, as shown here. This battery, dubbed the Aztec, was produced by Minnesota’s iconic 3M, and could power a transistor radio (apparently sold separately) for up to 24 hours with a pint of kerosene.

You can see a pristine example, apparently for sale, at this link, which also includes a link (currently broken) to one in a Canadian museum.

The American model produced a low voltage, which was stepped up to 6 volts with a transistorized power supply mounted in the base.  In addition to use in off-grid locales during peacetime, the set was billed as having a Civil Defense purpose for powering the important radio in the fallout shelter.



Girlstown, TX, 1962

1962MayPEShown here are Sandra D. Roberts, WN5ASZ, Donna K. Fomby, WN5APM, Linda L. Neal, WN5AOG, Ella R. Sanders, WN5AUJ, Bonnie J. Baggerman, WN5AUI, Nina C. Shaw, WN5AUQ, and Carol J. Fontenot, WN5APG, along with Vivian McCracken, the director of Girlstown, a home for 32 girls who had lost their parents near Whiteface, Texas. When a winter storm cut off their power, heat, light, and telephone, the members of the Terry County radio club decided that the facility needed amateur radio. Members made the trip every Friday evening to teach interested girls code and theory. As a result, the seven girls shown here obtained their novice licenses.

According to the May 1962 issue of Popular Electronics, they were set up on 80 and 40 meters with the Hammarlund HQ-180 receiver and Heathkit DX-60 transmitter shown in the photo, generously donated by the club members. The girls were open to schedules, and I’m guessing more than one novice kept on the lookout for these callsigns after getting the magazine. The magazine noted that classes continued, and at least four girls were at work on their general licenses.

As far as I can tell, only of of the girls in the photo retained her license after leaving Girlstown. As late as 1973, there was a listing for Sandra R. Heinrich, WA5ASZ, in Irving, Texas, seated at the left in the photo.



1942 Police Radiotelegraph Network

1942MayRadioNewsThere was a time when cops knew Morse Code, and one of those times was 1942, as described in the May 1942 issue of Radio News.

Shown above is the operator of the Indiana State Police radio station, which included three National HRO receivers and separate speakers.

Spanning 40 states, a network of about 100 such stations allowed rapid dissemination of police data from one part of the country to the other. Stations were classified as either zone or interzone. Zone stations generally operated within the same state, with interzone stations communicating nationally. Nine frequencies were available in the 7000, 5100, and 2800 kHz bands. Operating procedures followed those of the Navy, with Z signals used.

Coast-to-coast messages might be relayed up to six times. For example, the article cited a case in which a suspect was wanted for forgery in Tacoma, Washington, and believed to be en route to his home in Niles, Michigan. In that case, the Tacoma department used its interzone station to send the message to Denver, where it was relayed to Kansas City, and then to Springfield, Illinois, and then to Lansing, Michigan. The message was then sent by radiotelephone to Niles. Out-of-state vehicle registrations could be checked, as could emergency notifications.

With the country at war, the police network was also pressed into use for national defense. the Army Quartermaster Corps, fo example, had the duty of providing meals for troops being transported, and arrangements could be made thanks to the police network.

In case of enemy attack with communications disrupted, the police network with its experienced operators could handle communications to practically any place in the United States.

1942MayRadioNews2



Miss Radio News: 1947

Screen Shot 2022-05-06 at 10.13.57 AMShown here on the cover of the magazine’s May 1947 issue is Miss Radio News of 1947, Carmen Garcia, as selected at that year’s Radio Parts Conference and Show. She is demonstrating the Meissner “18th Century” AM-FM-Phonograph console.

The photograph was taken by Arthur E. Haug, a staff photographer for the magazine.



Automatic Radio Timer: 1942

1942MayPS11942MayPS2Eighty years ago, the May 1942 issue of Popular Science offered this solution for those who wanted to make sure they heard the latest war bulletins, but didn’t want the radio on at other times. With this system, the radio would turn itself on hourly, at the top of the hour, to play the latest news report. Then, it would shut itself off automatically until the next one.

This was accomplished with a clock (preferably an electric one, for better accuracy) modified as shown here. The glass was removed, and the switching unit here was installed. It consisted of two pieces of springy brass. When the minute hand came around, it would close the contacts and turn on the radio. For larger sets with more current draw, it was recommended to use auto breaker points. A switch in parallel would allow you to turn the radio off and on manually.

The recommendation was to set it to come on about 30 seconds before the hour, and shut off six minutes later, which would ensure being able to hear all hourly news broadcasts, with time for the set to warm up.



Simple 1962 Shortwave Tuner

1962SpringRadioTVExp4This young man is pulling in the shortwaves courtesy of an extremly simple circuit which appeared in the Spring 1962 issue of Radio-TV Experimenter.

The radio consisted of a crystal set, feeding into an audio amplifier module. The amplifiers were available from Lafayette and other retailers, and drove a speaker. The receiver itself consisted of just a germanium diode, along with coil and capacitor. The coil is wound on a ferrite core, and is seen protruding from the top of the set.

Despite the simplicity, the author was able to pull in signals from the strong European shortwave broadcasters with only a short antenna and ground. The set tuned about 3.5 to 7 MHz.

1962SpringRadioTVExp5



1942 One Tube Receiver

1942MayRadioCraftpEighty years ago this month, the May 1942 issue of Radio Craft showed how to put together this simple one-tube receiver. Being a battery set, there was no need to worry about hum, and the batteries were inexpensive. The B+ voltage was only 7.5 volts, so even with a large dry cell for the filaments, the battery cost was only 58 cents.

The set used a 1S4 tube as regenerative detector. It had two bands, which were switched by moving an alligator clip on the antenna coil. The overall tuning range was 480 kHz through 2.5 MHz, meaning that it covered the entire broadcast band, plus a little bit above and below. Thus, the set could also be used to pull in ships as well as police broadcasts.

1942MayRadioCraftS



1947 Three-Tube Regen

1947AprRadioNews6Seventy-five years ago this month, the April 1947 issue of Radio News, showed how to construct this three-tube (plus rectifier) regenerative receiver for the broadcast band and shortwave. Five plug-in coils covered the standard broadcast band, as well as the 160, 80, 40, and 20 meter ham bands, as well as adjoining shortwave broadcast frequencies.

The article noted that since the war ended, interest in shortwave had reached a new high, and this set provided a simple way to catch these signals. Due to scarcity of power transformers, and AC-DC design was used, with a 35Z5GT rectifier.

The radio itself consisted of a 12SJ7 regenerative detector, 12J5 first audio stage, and 50L6GT output, which provided loudspeaker volume to a dynamic speaker.

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