Category Archives: World War 2

1942 Air Raid Alarm

1942JuneServiceEighty years ago this month, the April 1942 issue of Service magazine carried this ad for the Model AR-101 Air Raid Alarm from National Union Radio Corp., 57 State Street, Newark, NJ.

For $5 plus installation, the small device was attached to “any type of radio set,” although I suspect the radio in question had to be a superheterodyne with AVC. But since most five-tube radios of the time fit that description, it was pretty close to “any type of radio set.”

During an air raid, radio stations would go off the air, so as not to serve as a beacon for incoming aircraft. According to the ad, the stations going off the air “are usually the first indications of attack.” The ad noted that during the early air raid alarms in Los Angeles, owners of radios with this device would have received warning six to ten minutes before the sirens sounded. And inside the house, the sirens might not be noticeable.

When the station went off the air, the radio equipped with this alarm would emit a “loud siren-like tone.”

According to the ad, the alarm was “sturdily constructed of the finest quality materials, and under normal conditions should last as long as the radio set and require no attention. In fact, the unit is sealed to prevent tampering, moisture, dust, or other deteriorating factors.”

And I suspect it was sealed for another reason–to conceal just how simple the circuit was, especially given the $5 price tag. The image in the ad shows a tiny box, with only a switch and what appears to be a potentiometer. The device had four wires that connected to easily accessible points in the radio.

1957ConelradI haven’t been able to find any more information about this device, but I suspect it’s very similar or identical to the 1957 “CONELRAD The Easy Way” circuit we featured previously. In that circuit, shown here, when the radio is set into the alarm mode, the AVC voltage is used to bias the first audio tube to cut-off, rendering the radio silent. But if the station goes off the air, the AVC voltage is zero, and the first audio stage comes back to life. The output from the final audio amplifier is fed back through the capacitor, resulting in feedback, or what the ad would call a “loud siren-like tone.”



1942 Airplane Detector

1942JuneRadioCraftCoverEighty years ago this month, the June 1942 issue of Radio Craft showed this walking airplane detector, then under development for use by the Aircraft Warning Service. The headset contained a parabolic microphone and headphones. When the operator heard the low-pitch rumbling of a plane, he could turn his body for the loudest sound, at which point he could look for the approaching aircraft with his binoculars.

The batteries and amplifier were contained in a case “smaller than the usual gas mask container.”



Battle of Dutch Harbor, 1942

Today marks the 80th anniversary of the Battle of Dutch Harbor, Alaska. On June 3-4, 1942, Japanese Aircraft attacked the naval base there, resulting in the deaths of 50 Americans.  The battle marked the first ever enemy air raid on the Continental United States.



1942 Anti-Theft Sign

1942MayRadioRetailingAs a public service, we present the image above. You can print it, and when your car is parked, you can display it, facing out, on the passenger side of your car. The idea is not ours. In fact, it originally appeared 80 years ago this month in the May 1942 issue of Radio Retailing.

Many radio men had written to the magazine lamenting the fact that even though theirs was a vital profession, they didn’t have any special priorities when it came to tires or gasoline. So when they went on a service call, their car parked out on the street was a sitting duck for thieves who could steal the spare tire. In some cases, the thieves were brazen enough as to jack up the car and steal the tires, wheels and all.

Several Western salesmen had come up with the idea of the sign shown here. It would alert passers by that the owner was absent, and anyone tampering with it was unauthorized. According to the magazine, the mere presence of such a sign would in many cases scare off the thieves from making an attempt. The magazine didn’t say so, but, of course, we doubt that any thief would dare target a car after learning that the owner was a radio man. We have no doubt that it would have the same effect today.



Smokes for Soldiers: Just 85 cents

1942May20PghAccording to this ad in the Pittsburgh Press 80 years ago today, May 20, 1942, many of our boys fighting overseas were unable to buy cigarettes at any price.

To solve this intolerable situation, Philip Morris came to the rescue.  For just 85 cents, you could send a carton to any APO or fleet address.  You just paid at your local retailer, they would pass the order on to their jobber, and Philip Morris would see to it that our boys had plenty of smokes.



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



1922 Automated Hunting System

1922MaySciInvSomething tells me that if you use this idea today, you  might have some splainin’ to do down at the game warden’s office. But a hundred years ago, this self-explanatory idea from the May 1922 issue of Science and Invention was apparently acceptable.

It was sent in to the magazine by one Venencio F. Lim, who explained that the birds sometimes flee when you get too close, so this system allowed him to observe through a telescope, after placing some bait in line with the shotgun shell. A battery, spark coil (probably from a Model T), and telegraph key rounded out the system. When the bird was in position, the key was pressed from a distance, and the bird dispatched.

Despite a variation in the spelling of the first name, it appears likely that the author was Venancio Lim, from the Philippines, a 1927 Electrical Engineering graduate of Purdue University. According to this page written by his great grandson, he went on to become the chief engineer of the national power company. He was imprisoned by the Japanese for a year, weighing only 80 pounds upon his release. He was later appointed to represent the Philippines in the War Reparations Commission, and he ultimately forgave the Japanese for his treatment.



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.



Navy Needs 500,000 Model Airplanes: 1942

1942AprBLEighty years ago this month, this naval officer was explaining to these scouts the finer points of model airplane construction. But it wasn’t just fun and games. These model airplanes were vital to the Navy’s training program, and Secretary of the Navy Frank Knox had called upon the youth of America to make a half million scale models–10,000 each of 50 different fighting planes.

In the April 1942 issue of Boys’ Life, Chief Scout Executive James E. West stressed how Scouts were especially equipped to handle this call. Models were had to be exact replicas of the ally and enemy planes, and were to be built to a precise scale of 1:72. At this scale, a model 35 feet away is identical to the true airplane at just under half a mile. Thus, Navy men could use these models for aircraft recognition, range estimation, formation flying, and other phases of the training program.

1942AprBL2Inspectors would review each model, which had to be perfect. Upon passing inspection, the model planes would immediately be put into service for training. Plans would be in the possession of schools, and the Navy pointed out that modern war was so complex that it demanded the skills of all, including the boy of 12, to provide some of the services and materials needed by our forces.

According to the Navy, “it is scarcely necessary to stir the interest of American boys and girls in aviation, since many of them expect to grow up to be pilots, and this project channels that interest toward an educational objective of immediate value.”

Elsewhere in the same issue, to give Scouts a head start, appeared the guide at left to recognizing some of the enemy’s planes.



Last Prewar Radio

1942MayRadioRetToday marks the 80th anniversary of the end of civilian radio production in the U.S. for the duration of World War II, and shown here is the last radio to roll off the RCA assembly line before the company switched over exclusively to defense production.

RCA was actually ahead of schedule, and this radio-phono was manufactured in Camden, N.J., on April 7, 1942. The chassis had been completed on March 5.

This last set was donated to the Georgia Warm Springs Foundation, where it would uplift the spirits and morale of the young patients there.

The picture appeared in the May 1942 issue of Radio Retailing.