Category Archives: Radio history

1937 Weather Balloon

1937JulSWTV

Shown here from 80 years ago this month is a weather balloon from the cover of the July 1937 issue of Shortwave and Television magazine.

1937JulSWTVschematicThe accompanying article explains the operation. The transmitter consisted of two type 30 tubes operating push-pull, as shown in this schematic. The system was developed under the direction of National Bureau of Standards physicist Dr. L.F. Curtiss, who chose the type 30 tube due to their low cost, since there was no guarantee that the set would be recovered, and also due to their low filament drain.

The 45 volt B battery was specially designed and built by Eveready, and represented the lightest weight B battery ever built.

When the hydrogen balloon was launched, it began transmitting pressure, temperature, and humidity. Keying was done by an electric motor. While the article didn’t provide details, it appears that the length of each signal encoded the data. On the ground, a superregenerative receiver hooked to a strip recorder was used, allowing the duration of each pulse to be measured accurately. A vertical dipole was used for reception of the signals, which were on exactly 55 MHz.

Not surprisingly, the airborne signals could be received over a long distance, despite the low power. The article noted that signals had been received over a hundred miles, and from altitudes as high as 127,000 feet (24 miles). When the balloon reached maximum altitude, it burst, with the transmitter descending on a small parachute. The article noted that the parachute was mostly to prevent damage to persons or objects on the ground, recovery of the transmitter apparently being a secondary concern. Dr. Curtiss noted that it was his hope that the transmitters would soon be made so cheaply that it would no longer be worthwhile to attempt recovery.



1957 Boys’ Life Hallicrafters Ad

1957JuneBLHallicraftersAdSixty years ago this month, the June 1957 issue of Boys’ Life carried this Hallicrafters ad, highlighting the excitement available on the shortwave bands.

The comic book style ad featured a young hero with the unlikely name of Billy Hallicrafters. Billy and his friend Tim have been out boating and were securing their boat after a quick storm blew up. Billy agrees that the storm is a bad one, and invites Timmy to come tune the marine frequencies on his Hallicrafters S-85.

An amazed Tim asks whether it’s really possible to listen to the fleet talking, and Billy assures him that it is. In addition to the exciting traffic from ships, he tells Tim that he can tune in police, fire, amateurs, planes, and foreign stations.

They get to Billy’s receiver, where on an international emergency frequency they hear a desperate distress call from a ship run aground on a reef and sinking. The ship tries in vain to raise the Coast Guard, but to no avail.

Our hero Billy quickly gets on the phone to the Coast Guard and gives the ship’s position. The Coast Guard tells him that they didn’t pick up the SOS, but had a cutter and plane in the area. Twenty minutes later, the Coast Guard has rescued the ship, which included an injured man.

In the next scene, Billy and Tim are down at the dock talking to the grateful Coast Guard officer, who tells them that this proves that shortwave listening is both exciting and fun.

An ambulance is seen waiting to take the injured man to the hospital, and it turns out that Billy had taken it upon himself to have the ambulance standing by.

Tim adds that he’s going to get his own Hallicrafters shortwave set.

Billy’s S-85 is revealed to have a list price of $119.95. For the more budget conscious Scout thinking of listening for distress calls, the ad also showed the venerable S-38D with a list price of $49.95.



GE Model 260, 1947

1947June22LifeSeventy years ago today, The June 22, 1947, issue of Life magazine carried this ad for the General Electric model 260 portable.  Shown in the ad is Monica Lewis, billed as a “popular star of radio and Signature Records.”

The set is touted as being self-charging, meaning that the 2 volt lead acid battery was constantly floating. When the set was run from 120 volts, the battery served as an effective filter capacitor. It had pushbutton tuning for the broadcast band, and also covered five shortwave bands, allowing it to “bring in U.S. and foreign stations galore.” It had “rugged military construction, and die-cast aluminum case that’s light as can be.”

The set’s tube lineup consisted of three 1LN5’S, 1LC6, and 1LH4. The internal battery powered a vibrator power supply, and when plugged in, the battery was charged while in the circuit, with a 3Q5GT serving as rectifier.

I actually owned one of these for a time.  By the time I owned it, the battery was long gone and unobtainium.  Without the battery in the circuit, the set did have a very pronounced 60 cycle hum.  It pulled in a few strong local stations, but shortwave was no longer an option.

Monica Lewis, who was 25 when this ad came out, went on to become the singing voice of “Miss Chiquita Banana,” a cartoon television commercial character. She made her way to the big screen, where she appeared in movies such as Airport ’77 and Earthquake. She died in 2015 at the age of 93.

You can see a video of the model 260 (along with a similar model that covered only the broadcast band) here:

And you can see and hear Miss Chiquita Banana here:

 



1947 One Tube Mailable Radio

1947JunePS

We previously featured a 1940 crystal set that could be mailed as a post card. And today, we up the ante to this mailable one-tube radio from the June 1947 issue of Popular Science. This one won’t go as a post card, but at just a quarter of an inch thick, it is small enough to mail in a 6 by 9 inch manila envelope.

The set used a subminiature 2E32 pentode tube. In addition to the radio, you would need a 22-1/2 volt B battery, as well as a penlight cell to light the filament.

The flat coil is wound on a 4 inch cardboard disk. The 92 turns are tapped at various points. By connecting to different taps, and by adjusting the trimmer capacitor, the set would tune most of the broadcast band. Even though the set did not use regeneration, it was said to be able to pull in strong local stations with high impedance headphones (also not included inside the envelope).

1947JunePSschematic



1937 Admiral 955-8K Chairside

1937JuneRadioRetailingShown here from 80 years ago this month is the Admiral model 955-8K chairside radio, as it appeared in the June 1937 issue of Radio Retailing.

The three band set featured automatic tuning, and in addition to the standard broadcast band, covered police and international shortwave bands. The walnut cabinet stood 24 inches high and featured an 8 inch electrodynamic speaker.

The semicircular front featured a built-in ashtray. The eight tube lineup consisted of 6A7, 6D6, 75, 80, and two each of 76 and 42.

The accompanying ad billed this and the rest of Admiral’s lineup as “America’s smartest radios for 1938.”



1942 Rochester, MN, Flood

1942June15BC

This photo of a flooded KROC, Rochester, MN, appeared in Broadcasting magazine 75 years ago today, June 15, 1942.

The picture was apparently taken on June 4, 1942, during a localized flash flood  along the Cascade creek which caused one death. Between June 3-5, the Rochester airport had recorded 3.26″ of rain, with 2.33″ of that falling within a single day. The creek basin had apparently received even higher rainfall.

The magazine noted that the station staff had to ignore the biggest news story of the year as it literally flooded right into the station’s doors. Due to wartime restrictions on weather reports, the announcer on duty had to ignore the waters rising around him, despite his strong desire to tell listeners about it as the water slowly climbed to waist depth.

“Just as the tubes began to sizzle,” they cut power and waited calmly for three hours until being rescued. While they waited, they were said to amuse themselves by warding off the rabbits, field mice, gophers, frogs, and pheasants that had sought sanctuary on the tiny island.

Damage was estimated at $1500, and the station was back on the air in less than 12 hours.



Radio Facsimile: 1947

4.1" facsimile receiver for connection to FM radio

4.1″ facsimile receiver for connection to FM radio

Today, we take a look at a technology that never caught on, namely, broadcast facsimile.

Seventy years ago this month, the June 1947 issue of FM and Television carried an article optimistically entitled, “Facsimile is Ready for Home Use,” detailing both the technology and the economic aspects. At that time, a standard had not yet been adopted, and the author, the magazine’s publisher Milton Sleeper, noted that this was the first step necessary to get the technology off the ground. Home receivers were ready to hit the market for $100, but sales were unlikely unless consumers knew that the set could be used to receive future facsimile broadcasts from any FM station.

The author advocated for a standard of a 4.1 inch width, 105 lines per inch, 3.43 inches per minute. He noted that this would require a subcarrier with an audio signal ranging from about 2-5 kHz, which he pointed out would be well within the flat-response range of all FM receivers. Others were apparently pressing for an 8.2 inch width, which he noted would require greater bandwidth.

The “chicken and egg” problem, of course, was content. As he noted, newspapers weren’t particularly keen on providing content to a free competing service. Even if they could be convinced, there was little interest in starting the service before receivers were on the market. And receivers wouldn’t be on the market without content.

Few, if any, technical barriers stood in the way. Sleeper describes how he set up a demonstration at a trade show on short notice. He was given the idea the day before the show, and managed to get the equipment installed at a station that same evening. The station had an experimental license, and apparently broadcast the facsimile over its normal audio channel. The receiver could be plugged in to any FM receiver, and was also set up in short order.

Sending unit, ready to plug in to FM station's audio line and play.

Sending unit, ready to plug in to FM station’s audio line and play.



Cooking With Sugar Rationing

1942JuneRadioMirror

Sugar rationing took effect in the United States in May 1942, and the next month, CBS radio personality Kate Smith stepped up to the plate in the June issue of Radio Mirror with recipes with which the housewife could conserve the commodity, but still prepare deserts.

Smith knew that her readers would accept rationing for what it was–“an emergency method of making quite sure that everyone gets all the sugar he needs and that no one gets more than he really needs.” She also knew that her readers wanted to make sure that they didn’t use their portion wastefully.

Therefore, she presented these recipes showing how delicious deserts could be prepared with other sweetening agents such as corn syrup, prepared pudding mixtures (which used dextrose), molasses, and honey.

Her sugarless layer cake used corn syrup, and the molasses cake used molasses along with a bit of brown sugar. She suggested that an easy and delicious filling for either cake could be made with a package of chocolate pudding mix and milk, following the package directions, but with a bit less milk. Instead of frosting, the cake could be covered with nut meats, currants, or raisins, or a light dusting of confectioner’s sugar could be used.

She also included a chocolate souffle recipe using a packaged pudding mix, and baked stuffed oranges using corn syrup or honey.

For glazing a ham, she included a recipe with a corn syrup glaze.

 



1957 Five Transistor Loudspeaker Superhet

1957JuneRadioElec

Sixty years ago, the transistor radio was starting to become more and more a reality, as shown by this project in the June 1957 issue of Radio Electronics.  A year earlier, the magazine had carried plans for a four-transistor superheterodyne pocket receiver.  and had announced that “this is it,” in that the transistor could finally be used in a usable radio that could be built by the average hobbyist.  The project shown here was an update of that project, and featured one thing missing from the earlier set, namely a speaker.

1957JuneRadioElec2This set boasted loudspeaker volume on many local stations, with the sound audible as far as 10-15 feet away in a quiet room. For distant stations or for private listening, an earphone jack was provided.

The set featured five PNP transistors, with four 2N1112A’s as converter, first and second IF, and detector, and a 2N138 providing enough audio to drive the speaker.  The set was powered by a 4 volt battery.  A specific battery was mentioned, but the article noted that three N cells providing 4.5 volts would work well.

1957JuneRadioElecSchematic



1942 Air Raid Alarm

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The June 1942 issue of Service magazine carried this ad for an air raid alarm to be added to any radio.  It noted that the first sign of an air raid would often be local radio stations leaving the air, lest they serve as a beacon for incoming bombers.  If you were listening to the radio during the day, you would know immediately.  But at night, with the radio off, you would be caught unaware.

With this home alert, you would leave the radio on standby, and if the station you were tuned to left the air, this would be the sign of a possible air raid.  The ad noted that during air raid alarms in Los Angeles, radios equipped with this device sounded the alarm from six to ten minutes before the sirens sounded.

The unit sold for $5, and could be installed by a local service shop.