Category Archives: Radio history

1917 Miniature Receiver

1917janpm2A century ago, the January 1917 issue of Popular Mechanics showed this surreptitious radio receiver having the size and appearance of a fountain pen. It was said to “make it possible for a man in the streets to pick up messages sent out from any station in the immediate vicinity.”

A tiny speaker was mounted at one end, behind which three small batteries provided power. The miniature audio tube was mounted at the other end, with coil and condenser behind it. Tuning was effected my moving a ring encircling the coil. Tiny connectors on each side were provided for antenna and ground. The antenna could consist of a wire running down a sleeve to a cane, and the ground was a wire running down the trouser to a metal plate in the heel of one shoe. To listen, the user could hold the cane at arm’s length into the air and put his heel against a fire plug or other metal object. By holding the tiny speaker into his ear, he could pick up messages without difficulty.



1917 Boys’ Life Transmitter

1917janblA hundred years ago this month, the January 1917 issue of Boys’ Life magazine carried the plans for constructing this wireless sending set. The author, A. Frederick Collins, had written the previous month on how to construct a receiver.

He notes that five parts are required: A spark coil, a tuning coil, a telegraph key, a spark gap, a battery, and an aerial switch, hooked up as shown here. The spark coil, the same type used for gas engine firing, was available for about five dollars. For those who wished to build their own, he directed readers to his own Book of Wireless, which contained more complete plans.

The tuing coil could also be procured for about five dollars, but he notes that a boy could easily make his own, and provides details.

He concludes:

A wireless telegraph set will give you all the apparatus you need for you to experiment with and theory to rack your brains over and on for the rest of your life, and it will also give you a liberal education in a highly specialized field of electricity.



Alien Surrender of Shortwave Radios, Cameras, Guns, 1942

1942janradioretailing

 

Shown here, in the January 1942 issue of Radio Retailing magazine, are resident aliens in Los Angeles lining up at a police station to turn in their cameras, guns, and radios capable of receiving short wave.

The magazine noted that Attorney General Francis Biddle had issued an order that enemy aliens, that is, citizens of Japan, Germany, and Italy, turn these items in to the nearest police station.  An alternative would be to have receiver rendered incapable of receiving signals other than those in the standard broadcast band.  Therefore, the order “seems to open the way for radio servicemen to render a useful service of eliminating shortwave reception from aliens’ sets–and get paid for it.  In this way, the alien may keep his set for regular broadcast listening to U.S. stations, while the police authorities are spared the storage of hundereds of radio sets which they are poorly equipped to handle.  And the radio man collects $1 to $2 per radio set altered.

Typically, the modification consisted of removing the shortwave coils, and providing the set’s owner with an affidavit documenting the modification.

75 years ago today, the Chicago Tribune, January 6, 1942, carried an article regarding the status of the order.  It reported that local officials found the response so far to be unsatisfactory, since fewer than 2550 cameras, guns, and radios had been surrendered as of the previous night, despite an alien enemy population of more than 50,000 (28,000 Germans, 21,000 Italians, and 250 Japanese).

The Chicago police reported that the items surrendered included several antiques, including an 1878 breach loader. One man was reported to have “embarrassedly handing over a sawed off shotgun, possession of which had been taboo in Chicago ever since the prohibition gang war era. He said that he inherited the weapon from his father.”

One man, not bothering to wait for a receipt, simply drove up to the police station, hurried a radio from his car, and drove away. Another motorist tossed a $100 radio from his car and drove off.

The paper also reported a supplemental order from the Attorney General listing the following prohibited items:

Weapons or implements of war or component parts thereof; ammunition of all kinds; bombs; explosives or material used in the manufacture of explosives; signal devices; codes or ciphers: papers, documents, or books In which there may be invisible writing; photographs, sketches, pictures, drawings, maps, or graphical representation of any military or naval installations or equipment of any army, ammunitions, implements of. device or thing used or intended to be used in the combat equipment of the land or naval forces of the United States or of any military or naval post, camp, or station.

 



Maybelle Carstens, KWSC, Pullman, Wash., 1927

1927janradiodigest

Shown here on the cover of the January 1927 issue of Radio Digest is Maybelle Carstens of KWSC, the radio station of Washington State College in Pullman, Washington.  According to the magazine, this “demure maiden” was a favorite of a large circle of admirers who listened to the station.  She was described as a reader and regular member of the staff.

The station originally came on the air in 1922 as KFAE, changing its call to KWSC in 1925. When the college became Washington State University, call letters changed to KWSU in the 1960’s.  It remains the flaship station of Northwest Public Radio.

About the same time that Miss Carstens was on the air, another student by the name of Edward R. Murrow had enrolled in the college in 1926 and got his start in radio at the station.



1936 Inter-Office Intercom

1936decradioretailingCallers to this 1936 factory were never asked to hold the wire. With this intercom from Sound Systems, this efficient information clerk was able to reach anyone in the plant instantly. The photo appeared in the December 1936 issue of Radio Retailing, which reminded readers that inter-office communication systems saved footsteps and sped up routine.



 

1941 Recordgraph

1941decradionews

Seventy-five years ago this month, the December 1941 issue of Radio News carried a detailed description of a sound recording system that, while very sophisticated for its time, was quickly superseded by magnetic recording, first on wire, and then on tape. The magazine described the sound-on-film recording system employed by the Recordgraph, shown above. This machine recorded sound on 35 mm film, but did not involve photography. Instead, the instrument was a sophisticated phonograph, mechanically carving a groove into the film, which did not have any photographic emulsion. Instead of a disc or cylinder, the grooves were cut into the film.

The great advantage of this system was the large amount of material that could be recorded. The market for the system was law enforcement, which could make sound recordings of, for example, a telephone line. The machine could be switched on automatically whenever a phone was off the hook or a radio carrier present. The film ran in a continuous loop at 20 feet per minute. The film could hold 100 tracks, meaning that only 6-1/4 feet of film were necessary for an hour of recording.

A well preserved example of the Recordgraph can be seen at this link.  A similar system, the Tefifon, was commercially produced in Europe, and can be viewed here:

The Recordgraph apparently saw at least some use by law enforcement.  The record from this 1949 New York case includes testimony describing how the device was used for telephone monitoring.

While the sound quality of this system is remarkably good, it was quickly supplanted after the war by magnetic recording, first on steel wire and then on magnetic tape.  The greatest advantage of magnetic recording was that the wire or tape could be erased and re-used indefinitely.

 



1925 Four Tube TRF

1925augpm

The August 1925 issue of Popular Mechanics carried the plans for this four-tube receiver. The set contained four type 201 tubes, and featured a tapped loop antenna. The set had very good selectivity by virtue of having the tapped loop. By changing the taps, the set tuned different portions of the broadcast band. On one tap, it tuned 370-550 meters (545 through 810 kHz). On another tap, it tuned 224-400 meters (750 through 1340 kHz). By breaking up the tuning in this fashion, a smaller range of frequencies was tuned by the single tuning condenser, resulting in greater separation between the stations.

The article noted that during testing in Chicago, even with the Chicago stations transmitting full blast, it was possible to receive more distant stations with the speaker.

Click Here For Today’s Ripley’s Believe It Or Not Cartoon



1936: World’s Smallest Three Tube Set

1936decradiocraft

Today, we offer this 80 year old miniature radio, which is barely visible.  The wearer is prolific radio writer Arthur C. Miller, who wrote the accompanying construction article.

He reported that the set, which used three miniature tubes, pulled in WCAU Philadelphia and WHAM Rochester from an office building in Midtown Manhattan. One of the tubes served as regenerative detector, with the other two serving as audio amplifier.

The antenna required some experimentation. The original idea was to wear it on the back, but the close coupling to the body meant that tuning and regeneration had to be readjusted after moving. Satisfactory results were obtained with the hat antenna, but the length required for the leadin added capacitance to the circuit, making the tuning range very narrow. He tuned the coil to 710 kHz, the frequency of WOR, and the set gave good results for WLW in Cincinnati on 700, and locals WEAF on 660 and WJZ on 760. He noted that by tapping the antenna coil, the tuning range could be increased.



1916 Boys’ Life Receiving Station

1916decemberbl

A hundred years ago this month, the December 1916 issue of Boys’ Life showed scouts how to put together this radio receiver and antenna. The author, A. Frederick Collins, explained that building the sending set might logically take precedence, but that with this set, you could listen in right away to what all of the other stations have to say. He pointed out that if you lived within a few hundred miles of any of the big government stations, you could get the correct time of day every noon, free of charge. He also pointed out that no license was required for a receiving station.

The cost of the complete receiving station was said to be about $5.



1916 Regenerative Receiver

1916decelectexp

Earlier this year, we posted a diagram of a regenerative receiver from January 1916, which was probably the first construction article detailing such a receiver. The December 1916 issue of the same magazine, Electrical Experimenter, contains this diagram of an unusual regenerative set.

This is basically two receivers, with the most expensive parts, the audion tube and variable capacitors, shared between them. Different coil arrangements could be switched into the circuit with a three pole double throw knife switch. With the switch set to the “Set A” circuit, it was a standard audion detector. With the switch flipped to the “Set B” circuit, it became a regenerative detector. Regeneration was controlled by the coupling between L2 and L1. In position A, the set could be used to receive damped waves from a spark transmitter. With it set to position B, it could be used for undamped continuous waves, and “a pure musical note may be obtained of any frequency, in the telephones.”

The accompanying article, by Samuel Curtis, Jr., first pointed out that the set could be constructed without the switch. But the circuit was designed this way because the parts were expensive.

The article noted that “the Audion bulb need not necessarily be of the most costly type, but can be any one of the tubular Audions. These bulbs give exceptional satisfaction in connection with this system, and if the experimenter should happen to be an owner of a frozen bulb, or one that will not oscillate properly, he will find that in most cases it will oscillate with this system.”

According to this site, the 1916 price of a tubular Audion was $11. As a point of comparison when looking at old prices, it’s good to remember that the cost would be 11 silver dollars, or about 11 ounces of silver. At today’s prices, this would translate to about $176. So the concept of economizing and building two receivers instead of one with the same tube doesn’t seem surprising.