Category Archives: Radio history

TV Antenna Tutorial from 1948

Screenshot 2023-05-24 10.13.12 AMScreenshot 2023-05-24 10.14.27 AMOver the next few years, the TV antenna on top of houses would become a familiar sight, But 75 years ago, the concept was new, even for experienced radio technicians, who were just starting to realize that the way they would stay in business was by embracing television.

Therefore, the June-July 1948 issue of National Radio News, the publication sent to alumni of National Radio Institute, carried an extensive treatise on the subject of antennas for FM and TV. One concept that would soon become familiar, but was probably new to most readers, was “ghosts” caused by multipath interference. The cause is shown above, and the result is shown below.

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1943 “Gibson Girl” Transmitter

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Eighty years ago this month, the June 1943 issue of Radio News showed the transmitter that was to become known as the “Gibson Girl.”  The two downed airmen had nothing but hope, and their potential rescuer was beyond the horizon, with no way of knowing they were there.

But that was soon to change, and the men would have with them a hand-cranked transmitter capable of summoning help over long distances, thanks to an automated message sent on 500 kHz.  Rescuers would be able to hear it for hundreds of miles, and zero in on their location through radio direction finding.

The antenna was to be made out of Belden wire, and they were justifiably proud of it.



1963 6 Meter Handheld Transceiver

1963JunQST2The June 1963 issue of QST carried the plans for this five-transistor transceiver for 6 meters. The author, David Light, K4IQU, reported a QSO of 15 miles between two of the units, in hilly terrain, presumably on two peaks within sight of each other. He also reported being heard 30 miles away (but not a two-way QSO) with a well equipped station with a beam at the other end.

As shown by the emblem on the set, the goal of the unit was for use in local emergencies.  But chances are, most of the use involved the secondary purpose, “having plenty of fun on 50 Mc.”

The superregenerative detector, the oscillator, and the RF amp were 2N1745 transistors.  Two stages of audio amplification were used for both transmitter and receiver, and used 2N43A transistors.  Power was supplied by a 9-volt battery.

For modern hams, the humble Baofeng handheld can be had for about $30, and almost certainly outperforms (on 2 meters and 70 cm) the humble little rig here.  So yes, if all you have is a Baofeng, there’s no reason why you can’t work another Baofeng 15 miles away, or a well equipped station 30 miles away.  There are much better radios, but if that’s what you got, there’s no reason why you can’t use it for having plenty of fun on 144 Mc.

 

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Electric Sentry for Air Raid Warden: 1943

1943MayPM5Eighty years ago, this west coast air raid warden was subject to call at any moment, but he might need to be somewhere in his house other than next to the telephone. His solution was to use something called an “electric sentry” to alert him.

As near as I can tell, an “electric sentry” was a one-way intercom, which used the house wiring to transmit the signal. The transmitter was plugged in near the telephone ringer. He could then carry the receiver to another room in the house, or even a neighbor’s house, with the assurance that he would hear the ringing phone.1943MayPM6

Here, he appears to have the sentry receiver nearby while he repairs a radio. His daughter assists him by trying on his warden’s helmet. The transmitter is shown at right.

The item appeared in the May 1953 issue of Popular Mechanics.



1938 One Tube Loop Receiver

Screenshot 2023-05-08 11.32.01 AMThe plans for this one-tube loop set appeared 85 years ago this month in the May, 1938, issue of Radio Craft. While the tuning range is not specified, it appears to be for the broadcast band, and the set was said to give the beginner many hours of enjoyment both putting it together and using it.

According to the magazine, the set was able to pull in signals inside a steel framed building, with enough volume to rattle the headphones.

While it was not primarily intended for use as an interference finder, the directionalScreenshot 2023-05-08 11.41.22 AM characteristics of the loop antenna made it well suited for that purpose.

The same issue of the magazine also showed how to make the one-tube all wave receiver shown at the right.  It also included instructions for adding an additional AF stage.

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1938 Audio Amp

1938MayRadioNews1Eighty-five years ago, this young woman was preparing to have her voice amplified with this 30-watt amplifier. We don’t know whether she’s a ham modulating her transmitter to almost 100% modulation, or if she is going to address a crowd through the loudspeaker. The circuit shown here, from the May 1938 issue of Radio News, is suitable for either purpose.

The power output was provided by two 6L6 tubes, and the circuit’s main feature was automatic volume limiting, which would provide distortion-free audio, even at maximum power. This was important for modulating, since the FCC required that modulation be limited to 100%. And for PA work, this meant that the output would be not only loud, but also crystal clear.

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1938 Pillow Speaker

Screenshot 2023-05-24 11.08.12 AMEighty-five years ago, this young woman was hospitalized. But she was in good spirits, thanks to the radio in her room. Despite her condition, she was able to listen to her favorite programs.

The notable thing about this photo is not the radio you can see, but what you can’t see. There is a wire headed toward the pillow, and under that pillow is a Hushatone crystal loudspeaker from the Brush Development Company of Cleveland, Ohio. It allowed her to listen without disturbing other patients. Wiring the speaker to the set was easy. It required tapping in on the primary side of the output transformer, and putting a switch in the radio to switch between the built-in speaker and the Hushatone. Volume could be controlled with the customary volume control on the set, or simply by shifting the position of your head in relation to the speaker.

While it is not visible in the picture, you can see what the Hushtone looked like at RadioMuseum.org.  The photo above appeared in the April-May 1938 issue of National Radio News.



1953 British Two Tube Receiver

Screenshot 2023-05-10 12.49.21 PMThe plans for this handsome little two-tube set appeared seventy years ago this month in the May, 1953, issue of the British Practical Wireless magazine. The set tuned both long and medium waves, and according to the construction article, it would pull in most of the BBC stations with reasonable volume.

Since the set relied on a transformer to run from the AC mains current, the design was quite safe. Tuning was accomplished by a switch attached to individual trimmers for each station.

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Pushbutton-ize Old Receivers, 1938

Screenshot 2023-05-08 9.16.54 AMThe wide-awake service man 85 years ago could increase his profits by modernizing his customers’ sets with the addition of pushbutton tuning. It was a simple matter, since the pushbutton assembly was available as a unit, and installation consisted of connecting three wires.

After the unit was installed, the individual trimmers were set for stations. One button disconnected the unit and allowed the user to use the main tuning dial. This item appeared in the May 1938 issue of Radio Craft.

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Billie Dove, 1923

1923MayRadioTopicsOne hundred years ago this month, the May 1923 issue of Radio Topics magazine’s cover featured twenty-year-old actress Billie Dove, who was evidently a radio enthusiast. She had begun her career a few years earlier as part of the Zigfield Follies, and had moved to silent, and then talking, motion pictures.

She was later engaged to radio amateur Howard Hughes, W5CY, but it was she who broke off the relationship.  She died in 1997.