Category Archives: Radio history

1945 Stromberg Carlson Radio

1945StrombergCarlson

Seventy years ago, the War was over, and American radio manufacturers were getting ready to deliver on the pent-up demand for radios, which had been out of production since early 1942. Stromberg-Carlson was no exception, as shown by this ad in Life Magazine, November 12, 1945, promising that the sets shown here would soon be available.

Interestingly, the FM sets covered two bands.  Since some prewar stations were still on the air on the old band, the sets covered 42-49 MHz.  But since that band would soon be depopulated and the stations moved to the new band, they also covered the modern 88-108 MHz FM band.

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Armistice Day Blizzard 75th Anniversary

Armistice Day Blizzard, Excelsior Blvd., West of Minneapolis. Minn. Historical Society photo, NOAA.

Today marks the 75th anniversary of the Armistice Day Blizzard, a deadly storm that hit Minnesota and surrounding states on the eleventh day of the eleventh month of 1940.  The strom came up suddenly and without warning, and resulted in 145 deaths, including 49 in Minnnesota.  The death toll was so high because the day started out unseasonably warm, but quickly and unexpectely turned into a severe blizzard to which many were totally unprepared.

I wrote about it previously, and focused on how amateur radio operators became involved.  A couple of names that later became familiar were involved.  Stan Burghardt, W9BJV, later W0IT, kept Watertown, South Dakota, in touch with the outside world, and Sherm Booen, W9HRT, who later became known for the World of Aviation program on WCCO-TV, was a key link from Albert Lea.

Broadcast radio also played an important role that day.  Booen was also employed by KATE radio in Albert Lea.  Even though personal messages were not normally allowed on broadcast stations, an emergency exception was made and some personal messages were broadcast.  Also, to establish contact with Mankato, the station broadcast a message and requested that KYSM in Mankato reply on its frequency.  A two-way link was established on the broadcast band, and some emergency messages were broadcast.  Local phone service was working in Albert Lea, and long-distance service was available in Mankato.  Therefore, the on-air link established a lifeline to the outside world.

In Willmar, Minnesota, station KWLM had gone on the air only a month earlier.  The station’s application had initially been rejected by the FCC on the grounds that Willmar was too small a community to warrant a station.  The blizzard proved this argument wrong, since the station provided an important link for that community as well.

The storm covered much of the Midwest, and in Chicago, it was notable as a severe wind storm. The area was hit with 65 MPH winds, the strongest since 1898. Among the victims was this 357 foot tower of a station then located in Gary, Indiana. The call letters of the station, and the cause of the tower collapse, are revealed on the transmitter building: WIND.

And now, as another Chicago broadcaster would say, you know the rest of the story.1940WIND

This image is from the November 15, 1940 issue of Broadcasting.

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1965 Northeast Blackout

Today marks the 50th anniversary of the Northeast Blackout of November 9, 1965.  During the afternoon rush hour, the power went out in most of New York City, as well as parts of the states of New York and New Jersey, New England, and Ontario.

Interestingly, the blackout was documented in part by an aircheck tape from WABC

in New York.  In the minutes before the blackout, the lights began to dim, but the frequency dropped from the normal 60 cycles per second to close to 50 cycles.  Since the station’s turntables used synchronous motors, the music slowed down noticeably.  The DJ even quipped that one recording sounded like it was in the key of R.  When the power went out, most FM and TV stations went off the air until the power was restored.  Most of the City was back on line around midnight, with power fully restored by six the next morning.

The New York Times managed to put out a ten-page edition, using the presses of the Newark Evening News.  Most telephone exchanges remained in service, thanks to battery backups and emergency generators.  Nonetheless, Amateur Radio operators reported for duty, and were on the scene a civil defense headquarters and hospitals, as well as their own homes and vehicles.  The activities of hams throughout the region were reported in QST in February 1966.  Nets on 2 meters and 10 meters were in operation in the New York metropolitan area as well as other areas.  HF traffic nets remained in operation continuously, but there was little additional traffic due to most phones remaining operational.

Massachusetts Governor John Volpe was reported a saying, “I understand that the performance of the radio amateurs on Cape Cod and the Islands during the recent blackout indicate you men lived up to the finest in the tradition of the radio amateurs.”

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1955 One Tube Reflex Radio

1955reflex

Sixty years ago, the November 1955 issue of Popular Electronics carried the plans for this little one-tube reflex receiver for the broadcast band.  With a very short antenna (just a few inches), the set was capable of loudspeaker volume thanks to the single tube being “reflexed.”  The single 6AU6 simultaneously amplified the RF and also served as a one-stage audio amplifier to drive the speaker.  The set used a 1N34 germanium diode as the detector, and a selenium rectifier, meaning that in the early days of radio, this would have been a three-tube set.

1955reflexSchematicThe author reported that the set picked up the Chicago stations from a hundred miles away.  The set was small enough to build into a wall or a piece of furniture, and instructions were provided to add a phono input or headphone output jack.

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Huffy Radiobike, 1955

1955Radiobike

Sixty years ago this month, Boys’ Life magazine, November 1955, carried an ad for this product.  It was almost certainly coveted by many of the readers, and I’m certain that Santa was flooded with requests for it that year.  It was the Huffy Radiobike:  A bicycle with a radio built in to the “tank”!   The ad promised that the radio was no toy, being rain-proof, tamper-proof, and shock-proof.  “You can drop your bike on the walk if you want to . . . but you probably won’t want to.”  The bike itself was well made, of the best materials, strong, speedy, and safe.

The ad also warned readers that “only one in ten thousand will have a Radiobike this Christmas.  Many stores will have only a handful all fall.  So the smart boy, or his dad, will call a Huffy dealer or write the Huffy Manufacturing Co. for catalog and dealer’s name, today.”

As noted in the ad, the radio itself was mounted in the “tank” of the bike and was a three-tube superhet, apparently manufactured by Yellow Springs Instrument Co. About 8500 units were manufactured. A schematic diagram of the radio is available at this link.

The tubes in the set were reflexed, with a 1R5 serving as converter, a 1U5 serving as IF amp, detector, and the first stage of audio, with a 3V4 serving as the final audio amplifier. The set was powered by a battery pack mounted behind the seat.

More information about the set can be found at nostalgic.net.

 

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Elegance in SWL’ing, 1956

1955Grundig

There was a time when people still dressed up to listen to shortwave radio, as demonstrated by this elegant DX’er, undoubtedly tuning in a shortwave broadcast on her Grundig Majestic Pianissimo console. The elegant cabinet, with its natural walnut finish, contained five loudspeakers, an AM-FM-SW receiver, and an automatic phonograph.

This ad appeared in Life Magazine, October 29, 1956. The ad also featured three more consoles tuning the shortwave bands, as well as two table radios. Prices ranged from $69.96 up to $1495, at better stores everywhere.

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How To Get Distant Signal TV Basketball, 1950

The reception problem and the final antenna.

The reception problem and the final antenna.

In 1950, Richard J. Buchan of Bricelyn, Minnesota, was apparently an avid basketball fan, and enjoyed following the Minneapolis Lakers. And he was apparently tantalyzed by the fact that the Lakers were carried on Channel 4 in the Twin Cities (then WTCN-TV), 105 miles to the north. WTCN also carried the state basketball tournament, and Buchan set out on a quest to pull those signals into his living room.

His quest had actually begun when KSTP came on the air on Channel 5 from St. Paul. Buchan was a ham (W0TJF), and “after studying antenna books and experimental charts put out by the FCC,” he came to the conclusion that KSTP would be putting out, at most, a 2.5 microvolt signal as far away as Bricelyn. He also knew that a 250 microvolt signal would be required for solid reception, a whopping 40 dB of gain. He set out on a yearlong quest to get those 40 dB of gain, and a “small set was purchased and connected up.” He initially began working on Yagi antennas and preamplifiers, and described his experimental quest in detail in an article in the October 1950 issue of Radio News.

Since he lacked any test equipment, he rigged a VTVM up to his television to serve as an S-meter, and set about experimenting. The Yagis and preamplifiers he tested were never enough to give him the elusive 40 dB of gain. In particular, to get sufficient gain from the Yagis, he found that the bandwidth was too narrow. If he maximized the gain for the audio, the video suffered, and vice versa. The problems were compounded by the entrance of Channel 4 to the airwaves with the elusive basketball games. He was soon resigned to the need for four Yagis, tuned for sound and picture on the two channels.

Much to his dismay, WOI-TV in Ames, Iowa, came on the air on Channel 4. Unfortunately, Ames was almost exactly 180 degrees away from Minneapolis, meaning that he now also had to worry about the front-to-back ratio of the Yagi. And by designing it for better front-to-back ratio, he lost gain. (Buchan reported that he made no attempt to tune in WOI, since it didn’t broadcast the elusive basketball games. As far as he was concerned, the Iowa station apparently represented nothing other than interference.)

After some more study, he finally decided to abandon the Yagis and instead go with a Rhombic, which would have a theoretically infinite front-to-back ratio, but still have sufficient gain to pull in the elusive basketball games. Fortunately for Buchan, he had a large field across the road where he could install the antenna, which measured 155 feet in length, pointed toward the Twin Cities. Even though the final rhombic was actually lower than the Yagis, it performed well. Other than “an occasional gurgle in the sound,” the QRM from WOI was eliminated.

Presumably, the antenna continued to function well until the Lakers left Minneapolis in 1959.

Buchan, whose amateur call sign expired in 1998, also published more detailed construction details in Rhombic TV Antennas in 1951.

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1955 CONELRAD Monitor at WRFD

1955WRFDConelradFrom 1951-1963, U.S. broadcast stations were required to participate in CONELRAD, a system designed to alert the public to enemy attack, but also deprive enemy bombers of radio signals which could be used for navigation purposes.  Under a CONELRAD alert, all stations would cease broadcasting on their normal frequencies. Designated stations would switch to broadcasting on either 640 or 1240 kHz.  The result would be that listeners would be able to hear alerts, but enemy bombers would hear only a confusing jumble of signals on those frequencies.

For the system to work, each station needed an alarm.  For smaller stations, this would consist of an alarm tuned to another station in the area.  If the primary station went off the air, then the smaller station would be alerted.  If it turned out to be an actual alert, they would need to leave the air or switch to their designated frequency.  Alarms were available commercially for broadcast stations, and simpler models were also available for hams, who were later required to participate in CONELRAD.  Many hams built their own, and there were many plans published over the years.  Sixty years ago this month, the October 1955 issue of Radio Electronics magazine carried the plans for the unit shown here, which was in use at WRFD, a Worthington, Ohio, 5000 watt daytime only station affiliated with Fram Bureau Insurance, with a format aimed at the agricultural market.

The author of the construction article was Harold Schaaf, the station’s chief engineer, who noted a critical defect in many of the existing CONELRAD alarms.  Most of them depended on a normally open relay which would close in case of an alert.  If the alarm circuit failed for some reason, there would be no relay action.

Schaaf noted that “such a system cannot be considered reliable, since it can go out of order without the operator knowing it.” Schaaf’s circuit instead included a relay that remained energized during normal operation. In the case of a circuit fault such as a failure of one of the tubes, the relay would de-energize, which would cause the alarm to sound, requiring the station operator to investigate. The result was what the title of the article described as a “failure-proof CONELRAD alarm.”

Like most other CONELRAD alarms, this one was hooked to the AVC circuit of a superheterodyne receiver tuned to the station being monitored. As long as there was an AVC voltage present, the alarm would remain silent. If the monitored station went off the air, the AVC voltage would disappear, which would trigger the alarm, which could consist of an external bell.

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1940 “High Fidelity Five” from Popular Mechanics

1940OctPMSuperhet

The plans for this five-tube superhet, dubbed the “High Fidelity Five,” appeared in Popular Mechanics 75 years ago this month, October 1940. It got this name due to its tone control circuit, which enabled the “small set to have a bass response comparable to that of a large receiver,” since the circuit could amplify the lower tones without distortion. The set also featured mechanical pushbutton tuning, with a tuning assembly that was commercially available. The project was not designed for beginners, but was “quite simple and well within the building range of the average experimenter.” Cabinet details were given, but the article mentioned that suitable cabinets were available for purchase.

The set had a transformer for both the B+ and filament voltages, and employed a electro-dynamic speaker, with the field coil also serving to filter the output of the power supply. While the full schematic and pictorial diagrams were given in the article, blueprints were also available for purchase.

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1940 Milwaukee Radio and Phono

1940EconomyBoysIf you were looking for a low-cost radio or phonograph 75 years ago today in Milwaukee, then Economy Boys would be the store to visit. In the store’s ad in the October 24, 1940, issue of the Milwaukee Journal,
we see this six-tube Grunow superhet broadcast receiver for just $8.77.

The phonograph, selling for just $9.45, is actually a “phono oscillator.” Instead of including an audio amplifier and speaker, this Karenola model contains a two-tube oscillator circuit, which broadcasts the radio sound to a nearby broadcast radio. Even if the radio is a low-price model without a phono jack, you simply tune to a blank spot on the dial to listen to your records.

At Economy Boys, you could take home either set for just a dollar a week.

Unfortunately, I wasn’t able to pin down the model number of either. Most Grunow radios I’ve seen had wood cabinets, and this one appears to be plastic or bakelite. The Karenola name is probably more familiar as Trav-Ler, since the phonograph was from the Trav-Ler Karenola company of Chicago.