Category Archives: Radio history

Battle of Midway and Aleutian Islands Campaign: 1942

SBD-3 Dauntless bombers of VS-8 over the burning Japanese cruiser Mikuma on 6 June 1942.jpg

U.S. dive bombers attacking Japanese carrier. Wikipedia photo.

Today marks the 75th anniversary of two battles of World War II in the Pacific. the Battle of Midway began on June 4, 1942, and the Aleutian Islands Campaign began the day before.

At Midway, the Japanese had intended to eliminate the United States as a strategic power in the Pacific. The Japanese had made faulty assumptions of American reaction, and American cryptographers had been able to determine the date and location of the planned attack. The battle was a U.S. victory, and all four of Japan’s large aircraft carriers were sunk. Along with the Guadalcanal Campaign which began in August, the battle is considered a turning point in the war in the Pacific.

Navy radio station at Dutch Harbor, AK. Wikipedia photo.

On June 3 and 4, the Japanese attacked the SuS. airfield at Dutch Harbor, Alaska.

The attack on Dutch Harbor prompted a blackout of radio stations along the West Coast of North America. According to the June 8, 1942, issue of Broadcasting, stations along the West Coast were silenced for more than eight hours, from 9:01 PM until 5:24 AM the next morning. This was the longest radio blackout to date. Stations in British Columbia, Canada, and Baja California, Mexico, were also off the air for about the same time period.

The magazine noted that the blackout resulted in heavy loss of revenue, but the West Coast stations “cheerfully dug in for the duration.” In most cases, full staff remained on duty. Station switchboards were flooded with calls from listeners, but “operators and attendants on duty kept the public reassured.” According to the magazine, “stations up and down the entire Pacific Coast area have been highly complimented by official Washington, the Army and Navy, as well as by an appreciative public for their efficient cooperation in following through on all orders given.”



“If All The Guys In The World” 1957

1957JunePEThe June 1957 issue of Popular Electronics includes these shots from the 1956 French film Si Tous Les Gars du Monde.  The magazine gives the film’s English title as If All the Men In the World, although the correct English title of the film as released was If All the Guys in the World.

According to the magazine,  the film prominently features amateur radio in a story of twelve sailors’ lives being saved.

The crewmen of a fishing trawler two days off the coast of Norway suffer from a mysterious illness. The ship’s radio fails, but the skipper turns to his ham set and raises FD8IM in French Togoland. That ham summons a local doctor, who correctly diagnoses the crew with botulism, and informs them that they must take the anitserum within 15 hours.

The race is on, and FD8IM contacts F8YT in Paris. Much international cooperation follows until the antiserum is successfully delivered.

According to the magazine, the film was received with great acclaim in Paris, Rome, Berlin, and Oslo, and was then touring America.

The movie doesn’t appear to be available in English or French.  More information about the English version is available at IMDB.  Information on the French version is available at this site.  It appears that the movie is based on a French novel of the same title, and used copies of that book are available at amazon.fr.

The following video includes the film’s French theme song, and includes clips from the film:



1942 QST: Visual Signalling

1942JuneQSTSignalling

75 years ago, American amateur radio operators were off the air for the duration, but QST kept rolling off the presses, and continued to encourage hams to hone their skills for the war effort.  One skill, of course, where hams had a natural edge was their knowledge of the International Morse Code, which was widely used both in the military and by government and civilian radio stations.

In the June 1942 issue, long time QST Editor Clinton DeSoto, W1CBD, wrote this article about methods of visual signalling. He noted that many a young amateur “joined up with the Navy or the Sginal Corps secure in the belief that because he knew radio he knew all there was to know about communications.”

But DeSoto noted that knowledge of CW and radiotelephone, and even a smattering of wire telephone and telegraph, covered only a part of communications methods then in use. In many cases, radio was unavailable, such in cases where a ship had to observe radio silence, and wires were not always an option. Therefore, especially in the Navy, but also in the Army Signal Corps, a knowledge of visual signalling methods was critical.

In the article, he gives a primer on the methods then in use, and encouraged hams to learn these methods. Those methods were (1) aural; (2) blinker; (3) wigwag; (4) semaphore; and (5) the international flag code.

DeSoto noted that aural signalling would require little or no new knowledge for a ham, since copying Morse from a fog horn or siren was no more difficult than copying CW on the air.

Copying code from a light blinker required a bit of practice, since the ham had to use a different sense to transmit the signal to the brain. However, he noted that most hams could acquire a speed of 8-10 words per minute with just a few hours practice. This speed was quite useful, since 12 WPM was about the maximum ever encountered in blinker work.

The third method, wigwag, was rarely used, but since it was also based on International Morse Code, most hams would have an edge when it came to using it. In wigwag, a single signal flag or light is used. It is dipped to the left (from the viewer’s point of view) for a dot, and to the right for a dash. Between dots and dashes, the flag or light is held vertically above the head.

Wigwag is very slow and cumbersome, and had a maximum speed of a couple of words per minute. For that reason, it was rarely used except when nothing else would serve.

The much more efficient system of signalling with flags is semaphore, and DeSoto devoted much of the article to its explanation. As shown in the diagram above, semaphore uses two flags held in the positons shown above. Semaphore had been around since Napoleon’s day, and in addition to flags, shore-to-ship communication, and even inland links, of the past had used stations with tall masts and giant signalling arms.

With practice, a skilled operator could achieve speeds up to 25 words per minute, making semaphore a vitally useful skill.

The article gave the basics of the procedure used. To begin, the sender would wave the flags for the attention signal, until the receiving operator answered with the acknowledgment “C”. As the sender completed each word, he dropped his arms to the “break” signal. At that point, the receiver would acknowledge with another “C”. If no acknowledgement was received, that word would be repeated.

Some of the prosigns and abbreviations used by hams were also used in semaphore. For example, the symbol AR was commonly used to indicate the end of a message.

Finally, DeSoto spent some time discussing the international flag code, which used individual flags for each letter of the alphabet. Each flag also had an independent meaning. Therefore, if a single flag was displayed on the signal mast, it was understood that it was conveying that message.

To minimize the number of flags that had to be carried, four flags were assigned as “repeat” flags. The “First Repeat” flag would be used to indicate that the first letter of the word was being repeated. The “Second Repeat” flag would mean that the second letter of the word was being used again.

The international flags were reproduced in the article, but in black and white. DeSoto warned that it wouldn’t be a good idea to attempt to learn them from those illustrations. He recommended either coloring them on the pages of the magazine with water colors or crayons, or simply making a set of identification cards in the correct colors. He also included the source of flashcards, available for 50 cents postpaid, or the official “International Code of Signals (Vol. 1, Visual and Sound)” available from the Navy Department for $2.25. A more recent edition of that text is available at this link.

This article would be of particular interest to Boy Scouts or their counselors working on the Signs Signals and Codes merit badge.  As I discussed previously at this post and this post, that merit badge includes Morse Code, semaphore, international flag codes, in addition to other topics.  Therefore, DeSoto’s 1942 article includes much of the information necessary to earn the merit badge.

Elsewhere in the same issue of QST (page 53), ARRL Communications Manager F.E. Handy, W1BDI, suggested a use for the signal flags. With amateur radio off the air, there would be no Field Day in 1942. Handy suggested that hams could use the traditional Field Day weekend, the third weekend in June, to make an outing to their usual Field Day location to practice some of these techniques:

Working in pairs, amateurs should call out characters as they are interpreted from the flags, impressing a bystander for ‘recorder’ if necessary. With some experience you will with to try for greater DX. Then we also suggest a planned trek to the usual FD location if you can make it on that third weekend of June. This will make a good outing for those of the group that can be rounded up; it will rouse afresh the memories of the last ARRL Field Day. Don’t forget to give the signal-flag idea a Field Day workout!



1937 Trailer “Private Address” System

1937JuneRadioCraft

Eighty years ago this month, the June 1937 issue of Radio Craft offered this idea for how the radio man could make life easier for the owners of the nation’s 250,000 trailers. The issue is billed as the “private address” number, and contains a number of articles about “private address” systems, or what we would more commonly call intercoms.

In this case, the wife, unencumbered by the nuisance of seat belt laws, is busy cooking breakfast while her husband motors to their next campsite. If they need to talk, they have the convenience of a private address system, possibly including a radio.

The magazine suggests that the radio is best mounted back in the trailer, where it benefits from a greater distance from the car’s ignition system, and where it has the possibility of a larger antenna. The sound can be piped to the driver, to be interrupted only when told that it’s time to pull over for breakfast.



1932 Police Converter

1927MaySWCraft

85 years ago this month, the May 1932 issue of Shortwave Craft magazine showed the plans for this simple one-tube converter to listen in to police calls, or, as the magazine called it, a “Thrill Box.”

The one-tube converter covered the frequencies just above the broadcast band to allow reception of police dispatchers.  According to the magazine, they were then using wavelengths of 121-125 and 178-180 meters (1.67-1.71 MHz and 2.4-2.48 MHz).  The set used an intermediate frequency in the broadcast band, allowing the standard broadcast set to listen in on the thrills.



1977 Indoor CB Antenna

1977MayEE1

For the woman shown in this picture, from an ad in the May-June 1977 issue of Elementary Electronics, the CB was probably her connection with the outside world, and her social life probably revolved around the good buddies she met on the air.  She was probably a REACT member, and used her CB to help motorists in need.

But she had a big problem when she moved into a new apartment where outside antennas were not allowed.  Fortunately, Hustler came to the rescue with this indoor CB antenna, dubbed the “Homing Pigeon.” According to the ad, this antenna was the answer to operating the CB from any location, such as a condominium, office, home, apartment, or motel. The spring-loaded antenna required no installation, and was supported by the floor and ceiling “like a pole lamp.” According to the ad, the range was “equal or superior to better mobile installations.”

Of course, the construction of the building probably played the biggest factor. Such an antenna would probably work well from a wood-frame house. From a building made of steel, it probably wouldn’t work quite so well. In this installation, placing the antenna next to the ductwork probably didn’t help.  But this was probably outweighed by getting it next to the exterior wall, and she probably got out pretty well in that direction.

When I worked for Radio Shack in an earlier lifetime, we sold a similar antenna, a half-wave coaxial antenna which sold for $34.95.  It was billed as “New for ’79” in the 1979 Radio Shack catalog.



History of the Coherer

1967MayPE1

Fifty years ago this month, the May 1967 issue of Popular Electronics took a look at the earliest days of radio. In particular, it looked at the coherer, and even showed plans for making the one shown above.

The coherer was one of the first methods of detecting radio waves. In 1850, the French scientist Pierre Guitard had discovered that dust particles in the air cohered, or collected together, when electrified. This principle was later used as a radio detector. Iron filings were placed in a glass tube, and in the presence of a radio wave, they cohered. The presence of the radio wave could be observed directly by looking at the filings. Or, more importantly, the iron filings would provide a current path to operate a bell or other device.

As far as I can tell, the coherer has absolutely no practical value today.  Even the most rudimentary crystal detector outperforms it, and has the added advantage of being much simpler to make.  But for those interested in experimenting with one of the artifacts of the earliest days of radio, the Popular Electronics article gives enough information to make a working example of the earliest radio detector.

1967MayPE3Electromagnetic fields were first predicted in 1864 by James Clerk Maxwell. It wasn’t until 1887 that this was proven experimentally by Heinrich Hertz, who transmitted a 75 MHz radio signal about 50 feet with the setup shown here. The transmitter consisted of a spark gap not unlike the transmitters used commercially in the early days of radio. The receiver consisted of a loop of wire with an open gap. The radio signal could be observed in the form of a spark in that gap. Hertz discovered that the range could be maximized by adjusting the size of the loop to the wavelength of the transmitted signal.

The next development was the the construction of the first coherer by French physicist Dr. Edouard Branley, which was used by British physicist Sir Oliver Lodge to detect and record Morse code signals sent by a spark transmitter.

After each electromagentic pulse, the coherer had to be decohered manually, since the iron particles remained in place even after the radio signal was gone. Lodge used a “trembler” to decohere the iron filings used in his coherer.

1989 Soviet stamp showing Povov demonstrating first radio, 1895, Wikipedia image.

1989 Soviet stamp showing Povov demonstrating first radio, 1895, Wikipedia image.

The coherer was improved considerably by the Russian physicist Aleksandr Stepanovitch Popov. He used the armature of an electric bell to decohere the particles. With this advance, it was possible to receive code at a reasonable speed. When a pulse was received, the particles cohered, which caused the electric bell to sound, which also decohered the particles. If a signal was still present, the process was repeathed. Popov also had the foresight to attach an antenna to the receiver.  With the antenna, Popov was able to achieve a range of 900 feet.

Basic circuit used by Lodge and Marconi.

Basic circuit used by Popov and Marconi.

Guglielmo Marconi improved the coherer in a number of ways. First, he evacuated the air and replaced the corks at the end with silver plugs. He also replaced the iron filings that had been used previously with a mixture of nickel and silver. Almost immediately, he had increased the range and was receiving signals from 2-9 miles. By 1901, he had increased the range to 200 miles. And on December 12, 1901, he used a coherer to receive signals over 2000 miles from England to Newfoundland.



Andreas Bertnes, LA6R, c. 1916-1941

1942MayQST2

This month 75 years ago, the April 1942 issue of QST carried this “stray” item announcing the death of Andreas Bertnes, LA6R, an amateur radio operator from Sendefyord, Norway, who was executed by the Nazis.

Bertnes, a medical student, was a member of a resistance group known as the Ask-gruppen.  The members were rounded up in March 1941.  Three, Bertnes along with Øyvind Ask and Johan Midttun, were sentenced to death on November 22.  They were executed by being shot on December 4 at Trandum.

Bertnes was one of four amateur radio operators executed during the war for their resistance activities.

Bernes was active on the air before the war.  He was listed in the “calls heard” listings by an English SWL on 20 meters in November 1937 and and April 1938.

Reference (and photo)



1942 “Command Performance, USA”

1942May24ChiTribSeventy-five years ago today, the May 24, 1942, issue of the Chicago Tribune carried this feature about the shortwave program Command Performance, U.S.A., which began each week with the words, “Command Performance, U.S.A. The greatest entertainment in America as requested by you the fighting forces of America throughout the world, this week and every week until it’s over, over there.”

The article noted that even though the program was intended for servicemen overseas, many Americans with shortwave receivers on the homefront had discovered it and were regularly tuning in.

The programs were transcribed in New York and Hollywood, and featured the biggest stars of the entertainment world offering their talents without charge. The article noted that “sometimes the language on these shows is just a little more robust than is passed by standard broadcasting stations. Jack Benny, as we recall, last Sunday night encouraged our fighting men to ‘give ’em hell.'”

The newspaper carried the schedule shown below of the stations covering the show, along with times and frequencies. It noted that some of the beams were not heard well in the Midwest, but pointed out that many were. For example, it noted that the 10:30 PM broadcast to Central and South America was being heard well in Chicago.

1942May24ChiTrib2

In addition to Command Performance, special news and sports programs were broadcast for the military, and some domestic programs were rebroadcast.



1957 Hi-Fi Phono Oscillator

1957RadioTVExpCover

Maybe your MP3 player sounds a bit better than this gentleman’s hi-fi turntable from 60 years ago, but I bet you can’t build yours from scratch, like this guy did.  This one, shown on the cover of the 1957 edition of Radio-TV Experimenter, is entirely homemade, and despite the homemade appearance, probably did sound as good or better than anything on the market at the time, and would probably have sounded good even by today’s standards.

It was actually a phono oscillator, and transmitted the signal through an FM transmitter.  Since the audio quality of the FM signal was better than the recording technology of the day, the fidelity was limited only by the quality of the record.

Sound quality was paramount in every detail.  As is plainly visible, the tone arm is indeed made out of wood.  In particular, the wood is basswood, chosen because it had less mechanical resonance than other woods.  Metal would have been inferior, because of the capacitive effect with the leads running through it.

The pickup was homemade, not as a cost-saving measure, but because the design shown here was superior to the ceramic cartridges then commercially available.  It used a capacitive pickup.  The only commercial component was the sapphire-tiped needle, which was pushed into a rubber plug.  A copper plate was carefully positioned next to the needle to complete the capacitive pickup.

The tone arm was cut with a jigsaw, and the article contained precise instructions for balancing it.

The electronics, probably the easiest part to construct, consisted of a small FM transmitter employing a single 6C4 tube.  The example shown here was to be used for 45 RPM records, but the article noted that by adjusting the size and using an appropriate needle, it could be built for 33 or 78 RPM records.