Category Archives: Radio history

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.



Mahlon Loomis: Inventor of Radio?

Loomis1965

It’s generally accepted in the history of science and technology that radio couldn’t have been invented until James Clerk Maxwell came up with Maxwell’s Equations in 1865.  That theoretically underpinning of radio were verified experimentally by Heinrich Hertz in 1887.  (Hertz, it turned out, was using electromagnetic waves of about two meters in wavelength, it turns, meaning that the first intentionally generated radio waves were probably in or near the two meter amateur band.)

The prevailing wisdom, which is more or less true, is that someone like Guglielmo Marconi in the 1890’s couldn’t have come along and turned radio into a practical device without the prior work of Maxwell and Hertz.

While that statement is generally true, it ignores Dr. Mahlon Loomis, a dentist and inventor who was born in 1826 and died in 1886, the year before Hertz’s experiments.  And it appears that in 1866, he successfully communicated wirelessly between two mountains fourteen miles apart.  Unfortunately, he produced no independent witnesses to verify the claim.  And his understanding was that some layer of the sky was completing a direct-current circuit, using the atmosphere as a conductor to send the direct current.

Even though his explanation is impossible, it’s likely that he was sending and receiving radio signals.  FIrst of all, his sending mechanism appears to have included a spark gap between the aerial and ground.  And more critically, Loomis found that the system would work only if the two aerials were extended to the same length.  He surmised that they were both coming into contact with the same level of the atmosphere, through which the DC current was conducted.  But the more likely explanation is that the two antennas were both resonant to the same frequency of radio wave.

In 1872, he was issued U.S. Patent 129971 for his wireless telegraph.  And in 1873, the U.S. Congress even chartered the Loomis Wireless Telegraph Company.  Loomis was, however, never able to raise sufficient capital to make the venture a practical reality.

It’s probably true that radio pioneers such as Marconi couldn’t have succeeded without Maxwell and Hertz telling them that it was theoretically possible to send electromagnetic waves through space.  But it’s not a foregone conclusion.  Loomis shows that history could have played out the other way around:  Someone could have accidentally discovered radio (as it appears that Loomis did), and only then the physicists could be called upon to explain how it works.

Fifty years ago this month, there was an interesting article about Loomis in Popular Electronics, October 1965, written by Thomas Appleby, W3AX.  The illustration above is taken from that article.  Appleby was also the author of Mahlon Loomis, Inventor of Radio, published in 1967.

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1938 “Live” Broadcast by Caruso

Late1910sRecordingTenor Enrico Caruso died in 1921, but the January 1938 issue of All Wave Radio magazine noted that the program “The Music You Want to Hear When You Want It,” sponsored by RCA-Victor occasionally carried a “recreated Caruso record” with the voice of Caruso and a recreated orchestral accompaniment. Recording technology had advanced a great deal in the intervening years, as shown by the accompanying photograph of an early recording session, probably taken in the late 1910’s.

In Caruso’s day, it was necessary to record the entire performance thought a single horn. The article explains how the violins were placed near the horn for maximum pickup. The frequency range possible meant that the drums wouldn’t be picked up well anyway, so they were situated near the rear.

The soloist’s voice would, however, be picked up well, and the frequency range of the early recordings faithfully preserved Caruso’s voice. Therefore, it was possible to do a recreation broadcast. Using more modern electronic methods, the orchestra could be picked up well. A new live orchestra accompanied a perfect copy of the old recording for broadcast. The conductor wore headphones, listening to the recording as he conducted to keep perfect time.

The result was a new “live” broadcast of Caruso.

Enrico Caruso



1941 Model RCA Victor Radios

1941RCA75 years ago today, the October 21, 1940, issue of Life Magazine carried this two-page ad showing what would be some of its last prewar radios, from the company’s 1941 model year. The ad points out that even for your home’s extra radio, you can get RCA Victor quality at a low price, since the models start with the the model 45X-1, later dubbed the “Little Nipper,” for $9.95.  This inexpensive set was billed as having, in addition to standard broadcast, “one police band.” A closer inspection reveals, however, that the “police band” means only that it tunes above the standard broadcast band to 1720 kHz, so that police calls in many cities could be heard at the top of the standard AM dial.

Families wishing to tune in to foreign broadcasts with their “extra” set could do so for as little as $19.95 with the model 16X-11, which tuned standard broadcast and one short wave band. Many of the sets featured a “plug-in for Victrola,” meaning that an external phonograph could be added. The least expensive combination radio-phono was the model V-100 for $29.95.

With the end of civilian radio production on April 22, 1942, virtually all of these sets would see service for the next five years, providing war information to their owners.



Sally Bell, West Coast Radio Star, 1925

1925SallyBell

Ninety years ago this month, Radio Age magazine, October 1925, carried this photo of radio star Sally Bell, in what the magazine called an “exceedingly piquant pose.” It notes that she was capturing the hearts of listeners with her eccentric programs with her trusty ukulele. Apparently a California girl, she appeared most consistently on the Hollywood and Los Angeles stations.



1915 Boys’ Life Receiver

1915SKReceiverA hundred years ago this month, Boys’ Life Magazine carried this ad for a “special station for receiving time signals.” For six dollars, the set included the transformer, loading coil and condenser in a mahogany case. Switches were mounted on the front, with a sensitive cat whisker detector on the top. This set came complete with headphone with silk cord and leather covered headband. The ad reported that other sets were avalable starting at two dollars.

The set was supplied by the S. & K. Electric & Mfg. Co., of 302 Sackett Street, Brooklyn, New York.  From the picture, the set appears to be well made, and would undoubtedly pull in the signals from NAA within several hundred miles of Arlington.



1955 British Two Valve “Meteor Mini-Receiver”

1955Meteor

Sixty years ago, the British publication Radio Constructor carried the plans for this simple two-tube receiver in its September, October,
and November 1955 issues. The receiver was dubbed the “Meteor Min-Receiver,” and used an EF41 tube as a regenerative detector, tuning 730 kHz through 32 MHz with the specified plug-in coils. An EL42 was used as a one-stage audio amplifier for driving a pair of headphones.

1955MeteorSchematicThe receiver was apparently a popular design, since subsequent issues of the magazine carried advertisements from multiple suppliers offering the particular parts that were needed.

In addition to the main tuning control, the three smaller knobs are the antenna trimmer, the bandspread, and the regeneration control.  The airplane and “Meteor” logo on the upper right hand corner aren’t a control, as it appears at first blush.  That’s simply a decal which was available at a bicycle shop, used to give the little homemade receiver a brand name and logo.

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