Monthly Archives: November 2015

1937 Westinghouse Chairside

 

1937Westinghouse

This young woman is undoubtedly tuned in to a foreign shortwave broadcast as she shows off her 1937 Westinghouse chairside console. The seven tube set featured a slanted dial panel for easy chairside tuning. The accompanying caption in the November 1937 issue of Radio Retailing notes that the set also featured vertical grille pilasters to add a distinctive note to the cabinet. It tuned 540 kHz to 18 MHz and included a “precision eye” tube.

The magazine didn’t include a model number, and I wasn’t able to track one down. If you have more information on this set, please leave a comment below.

To get some idea of what signals she might have been trying to pull in, the August 21, 1937, issue of Radio Guide gives some ideas. The MacGregor Arctic Expedition was underway aboard the General A.W. Greely, en route to Fort Conger, Ellesmere Island. The NBC network was carrying updates, which originated from W10XAB, a 400 watt transmitter aboard the ship.

Another curious broadcast, which took place on August 17 is somewhat chilling in light of the fact that the Nazis were by then firmly in control of Germany and the stations in question. The German stations DJB and DJD were to “feature a special broadcast to the State of Minnesota. Just seventy-five years ago to this very day, the Sioux Indians made their last assault on New Ulm, Minn., founded by German emigrants from Swabia, from the old town of Ulm, famous for its cathedral. This event and more so, the quick reconstruction of New Ulm, are fine examples of the part which German settlers had in making Minnesota a prosperous and busy state. The station hopes listeners in New Ulm will be particularly interested in tuning in this broadcast.”

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Radio Scouting, 1919

1919Wilkins

According to the National Eagle Scout Association database, on this day 95 years ago, November 29, 1920, Scout Jack Wilkins  of 715 North Boulevard, Atlanta, a member of Troop 15, became an Eagle Scout.  This achievement was reported in the Atlanta Constitution, December 4, 1920.  This, however, wasn’t the first time this Scout had appeared in the newspaper.

In 1919, Mr. Wilkins, then 15 years old, was featured in Atlanta’s Sunday American, and the article was reprinted in the November 1919 issue of Radio Amateur News, with the photo shown here.

The article, entitled “Scout Jack Wilkins is a Young Marconi” reports that Wilkins had completed his station and was able to receive radiograms every night from Arlington, Key West, Florida, and other government stations, as well as ship stations along the Atlantic seaboard. His station, described as efficient and orderly, used a four-wire antenna. Since American amateurs were still off the air, the article reports that Wilkins was waiting impatiently for permission to “throw on the rotary gap and send 15,000 volts flashing into the air bearing his messages.”

I didn’t find any record of Wilkins holding a license in 1920, so it’s unclear as to whether he was able to unleash that rotary gap. The article reports that he was also working on a portable set to use in connection with scouting activities.

The article also identifies another scout from the same troop, Welsh Geeslin, who had operated a station before the war.

 

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1941 Dictator: The Ideal Gift for the Whole Family!

1941Dictator

By November 1940, Canada had been at war with dictators for over a year.  But this ad invited Canadians “in tune with the times, for Christmas, give a 1941 Dictator, the ideal gift for the whole family!”  This ad appeared 75 years ago today, in the November 28, 1940, issue of the Vancouver Sun.

At some point in the 1930’s, someone at the Hudson’s Bay Company department stores decided that “Dictator” would be a good name for their own brand of radios, most or all of which were manufactured by Dominion Electrohome Industries Limited of Kitchener, Ontario.  Presumably, they had a lot of nameplates printed up, so they continued to use them on early wartime models such as this one.

Both the six tube ($74.50) and eight tube ($94.50) featured pushbutton tuning, and both covered short wave, so I suppose both of them could, indeed, bring a dictator into your living room as you tuned the wartime shortwave bands to listen to the voices of Hitler or Mussolini.

 

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1943 One Tube AC-DC Regen

1943OneTubeACDCIf you were lucky enough to have in your wartime junkbox a dual triode such as the 6C8G, you could turn it into a regenerative receiver suitable for both broadcast and shortwave bands.  This circuit was sent in to the March 1943 issue of Radio Craft by one Leo Silber of Springfield, Mass., who appears to have been a high school senior at the time.  It used one half of the tube as a rectifier, with the other half serving as a regenerative detector. To deliver the filament voltage, the set used a 390 ohm “curtain burner” line cord. With four plug-in coils, the set would cover 500 to 15 meters.

Mr. Silber reported that the set pulled in signals from all over the world. His best DX was apparently logged before the War, KC4USB at Little America.  He doesn’t appear to have been licensed before the War, but the 1949 call book shows him as holding W1NRP.  A 1981 biography is available at this link.

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Happy Thanksgiving!

On this Thanksgiving, we look back to Thanksgiving seventy years ago, when America and the world gave thanks for final victory, as expressed by President Truman:

In this year of our victory, absolute and final, over German fascism and Japanese militarism; in this time of peace so long awaited, which we are determined wit all the United Nations to make permanent; on this day of our abundance, strength, and achievement; let us give thanks to Almighty Providence for these exceeding blessings.

We have won them with the courage and the blood of our soldiers, sailors, and airmen. We have won them by the sweat and ingenuity of our workers, farmers, engineers, and industrialists. We have won them with the devotion of our women and children. We have bought them with the treasure of our rich land. But above all we have won them because we cherish freedom beyond riches and even more than life itself.

We give thanks with the humility of free men, each knowing it was the might of no one arm but of all together by which we were saved. Liberty knows no race, creed, or class in our country or in the world. In unity we found our first weapon, for without it, both here and abroad, we were doomed. None have known this better than our very gallant dead, none better than their comrade, Franklin Delano Roosevelt. Our thanksgiving has the humility of our deep mourning for them, our vast gratitude to them.

Triumph over the enemy has not dispelled every difficulty. Many vital and far-reaching decisions await us as we strive for a just and enduring peace. We will not fail if we preserve, in our own land and throughout the world, that same devotion to the essential freedoms and rights of mankind which sustained us throughout the war and brought us final victory.

Now, Therefore, I, Harry S. Truman, President of the United States of America, in consonance with the joint resolution of Congress approved December 26, 1941, do hereby proclaim Thursday November 22, 1945, as a day of national thanksgiving. May we on that day, in our homes and in our places of worship, individually and as groups, express our humble thanks to Almighty God for the abundance of our blessings and may we on that occasion rededicate ourselves to those high principles of citizenship for which so many splendid Americans have recently given all.

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1955 One Transistor Regen Using CK722

1955CK722Regen

1955CK722AdSixty years ago, the editors of Popular Electronics had been flooded with inquiries after one of the Carl and Jerry stories included a transistorized pocket broadcast receiver, in which Carl and Jerry commented on the size and sensitivity of the receiver. The story neglected to give the brand name, and readers wanted to know what it was. It turns out that the boys were talking about the Regency portable that was featured here previously.

The flood of inquiries convinced the editors that “transistors are here to stay,” and as a result, the November issue began a feature called “Transistor Topics.” It included the receiver shown above, which was sent in by one Mr. R. Zarr of Brooklyn, New York, a one transistor regenerative receiver for the broadcast band, using the venerable CK722 transistor, which was advertised in the same issue for $1.25.

As shwon, the set would tune about 400 kHz of the broadcast band, the exact center of which was determined by adjusting the slug of the coil. The set had about the same sensitivity as a good crystal set, the great advantage being very good selectivity.

The editors noted that by substituting a CK760 transistor, the set could probably be made to oscillate up to about 4 or 5 MHz.

1955CK722RegenSchematic

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1943 Code Oscillator and Regenerative Receiver

1943Regen

Amateur station licenses weren’t being issued during the war, but the FCC continued to conduct exams and issue operator licenses. And there was a big demand for operators, both in the military and commercially, so learning Morse Code would be an important skill in 1943, and the January and March, 1943, issues of Popular Mechanics carried companion projects to assist a student in learning the code. The January issue carried plans for a simple code practice oscillator using a 25A7GT tube which ran on 120 volt house current. The set was billed as a “safety code oscillator,” the safety feature being that both the filament and B+ were dropped down to 25 volts by use of a “curain burner” resistance line cord.

The writer, W9SFW, seems to have realized, however, that the setup wasn’t totally safe. Depending on how the plug was inserted, there was a 50/50 chance that the exposed “ground” connections on the exposed chassis were actually hooked directly to 120 volts. The solution was to plug it in the other way. In the case of the code oscillator, this would be apparent, since the oscillator would make noise even with the key up.

The March issue carried a simple one-tube regenerative receiver, using the same tube and many of the same parts. Since listening to actual code on the air was the best way to learn, this set would allow the builder to tune about 6-11 MHz, frequencies that would have been packed with CW signals during the war. The author notes that “once some code efficiency is obtained, listening-in on actual code signals is the best way to increase your code receiving speed and learn real message-handling procedure that will be of help in service training.

Since unlike the oscillator, the receiver would operate just fine even with the chassis “hot,” the article advises that the polarity of the cord should be tested and then marked. To test it, a light socket was hooked to one of the ground points, with the other side to an actual ground. If the bulb lit up, then the plug was the wrong way and should be reversed. With the correct polarity and the “curtain burner” cord dropping the voltage, the set would be relatively safe.

It should be noted that there’s really no safe way to build this set on an exposed breadboard without the “curtain burner” cord. Even though polarized cords are available, which are a step in the right direction, there’s another problem. One could use a sufficiently large 330 ohm resistor to drop the voltage, but one end of that resistor would still have 120 volts on it. If you do overcome that safety obstacle (by not leaving connections exposed), all of the parts required for this simple set should be readily obtainable. The set uses two variable capacitors, one for tuning and the other for regeneration. As discussed in the article, the exact values are not critical. The coil is wound on a cardboard form. The fixed capacitors are readily available, with the added bonus of the modern equivalents being much smaller than the 1943 versions.

The tube is a dual tube, and in both circuits, half the tube is used as the rectifier.

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Science Fair Idea: Homemade Microphones

1945Microphone0

For the aspiring mad scientist, young or old, the November 1945 issue of Popular Science shows how to make several homemade microphones.  If you’re a student looking for a science fair project, then building your own microphone is probably going to impress the teacher more than a homemade volcano.  While other kids might even put together electronic projects, it’s unlikely that very many of them will put together individual electronic components.  And since most people think of microphones as sensitive and complicated instruments, you’ll probably be the only one to think of it.  You’ll discover that most of them are quite simple to construct, although there’s no need for you to share that little secret with the judges.

1945Microphone1The first design, shown here and in the photograph at the top of the page, is simplicity itself.  It consists of little more than three nails, one resting precariously on top of the other two.  When struck by sound waves, the top nail vibrates, causing a slight change in resistance.

1945Microphone2The second design, shown here, is only slightly more sophisticated.  It is a carbon button microphone, and consists of carbon granules in a small container, such as the cap of a ketchup bottle.  As sound strikes the granules, the resistance changes.  This setup requires a slightly higher voltage, but will give you considerably more audio output.  The carbon granules can be obtained by cracking open a carbon-zinc battery (the cheap kind), removing the carbon rod in the middle, and crushing it up.  A double-button design is also shown for the advanced student.

1945Microphone3A homemade dynamic microphone is shown here.  It consists of a coil of wire mounted between two magnets.  When the coil moves as a result of sound, the microphone becomes a tiny electric generator producing an AC current in time with the sound.  Unlike the earlier designs, which simply varied the resistance, this one requires an amplifier to amplify the tiny current generated.  In 1945, this probably posed a bit of a problem.  But today, you can easily connect it to a cheap audio amplifier such as this one and get plenty of audio to impress the judges.  You can also simply plug the microphone into the microphone input of a computer.  Another variation of the dynamic mike, also described in the article, is the ribbon mike, which substitutes a thin ribbon of foil for the diaphragm.

1945Microphone4The final, and most advanced, microphone described in the article is shown here.  This is the piezoelectric or crystal microphone, which your teacher would probably tell you is impossible to make at home.  But your teacher is wrong, as shown by this 70 year old article.  You simply grow yourself a suitable piezoelectric crystal and arrange it as shown here.  While it might sound intimidating to grow a crystal, this is actually the same thing your less advanced peers are doing by making rock candy as their science fair entry.  Instead of using sugar to make the crystal, you use Rochelle Salt (potassium sodium tartate). Your chemistry teacher probably has a dusty bottle in the lab. If not, you can simply buy some on Amazon.  Like the dynamic microphone, this one is hooked up to an audio amplifier.

If you’re a student, your teacher is probably tired of homemade volcanoes, potato clocks, and other scientific curiosities that he or she has seen a hundred times before.  Your homemade microphone(s) will be most impressive.  And even if your school days are behind you, making these simple microphones will be quite rewarding.

 

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1940 Popular Science One Tube TRF

1955NovPS

Seventy-five years ago this month, Popular Science (November 1940) carried the plans for this one-tube loudspeaker set for the broadcast band.  While it’s technically a one-tube set, it actually has two stages, since it employs a dual pentode, the 1E7G.  One half of the tube acts as an RF amplifier, with the other half serving as detector and AF amplifier.

1955NovPSschematicWith a good outdoor antenna, the set was said to provide good reception on all local stations. With a station ten miles away, and indoor antenna could be used. It had good selectivity such that powerful stations just 30 kc apart could be easily separated.

Since it was a TRF set, it employed two tuning condensers. The first tuned in the RF amplifier stage, with the second one serving as the main tuning condenser. The set’s volume was adjusted by a rheostat adjusting the filament voltage of the AF amplifier stage.

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Radio Scouting, 1940

A sampling of the author's QSL's.

A sampling of the author’s QSL’s.

Seventy-five years ago this month, the November 1940 issue of Boys’ Life carried a one-page plug for Amateur Radio entitled “DX Hams Do Get Around.” The author, Larry Le Kashman, W2IOP, starts by explaining how hams can “hold a conversation annihilating time and space by the touch of a switch,” and goes on to explain the licensing requirements. After a rundown of things like call signs and Q-signals, he moves to some of the exciting things that happen on Ham Radio, undoubtedly of interest to young scouts who wanted to Be Prepared. He tells a couple of tales (lacking in many details) such as that of a ham in California who was working a station in New Zealand until the latter suddenly left the air. The worried Californian managed to make contact with another station in the same town who investigated. The first New Zealander had been overcome by gas, and the quick actions of the California ham saved his life. Another unnamed station somewhere in the Midwest “was held up by thugs while his phone transmitter was on the air. The station he was talking to make a long distance telephone call and the distressed ham was rescued in short order by the police.”

Le Kashman included a few more corroborating details when talking about what hams did during hurricanes and floods. (However, many of the corroborating details for a flood “last winter” sounded suspiciously similar to what had actually happened in 1936.)  But the exact details were less important than the compelling story the article told:

Perhaps you were wondering what was happening in the cold Eastern states when flood waters started rising last winter. Had you turned on a short wave receiver you might have heard the first sharp signal pierce through the night with a frantic appeal–“QRR QRR,” the land SOS shattered the ominous stillness of the black night. Amateur activity ceased in an instant–from coast to coast ears were strained listening to the troubled frantic calls for help. With no wires, no roads, no power, the stricken cities were relying upon battery operated amateur stations. News services, starving for stories called on the radio amateurs.

Endless hours passed as the drama unfolded. At 2 A.M. the first flood missages came through. At 3:05 W8WBH, operating from the Pittsburgh area,  wired frantically for aid. All wires were down. Snatches of messages came through the interference, only to end in a tragic blurred whine, as power failed. Cold, gray dawn broke on operators racing against time. State after state went under the rushing, conquiring, relentless deluge, and their only link with the outside world was the isolated hams. An ominiously curtailed message from New Cannan read, “WATER 3 FEET STILL RISING.” At 10 A.M. a plane missing between Springfield and Albany was reported safe.

The author concludes that this “is the kind of stuff that makes amateur radio!”  And it turns out that the author knew a thing or two about amateur radio.   Born in 1921, Larry LeKashman was only about 19 when he penned this article, but he was already a prominent amateur. Until his death in 1978, he had held calls W2IOP, W8IOP, W9IOP, and W2AB. His career included serving as an editor of CQ magazine, and employment by RCA, Lafayette, and Bogen Electronics. In the 1950’s, he was the vice president of sales at Electro Voice, a position he held until his death.

The year before the Boys’ Life article, 1939, he had taken the top place in the ARRL CW Sweepstakes,  a feat he repeated in 1948, 1949, 1953, 1957, 1959, 1960, and 1963.  The connection with Boys’ Life isn’t suprising, since the National Eagle Scout Association database reveals that he became an Eagle Scout on September 11, 1934, in Troop 1, Oakland, Maine.

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