Seventy-five years ago, the May 1940 issue of Popular Science carried the plans for this novelty crystal set that was suitable for mailing as a letter. You could slip it into an envelope “and mail to one of your radio-minded friends as an amusing birthday or holiday greeting.”

The radio was sandwiched inside two postcards, with the detector and taps for the tuning coil exposed. Connections for antenna, ground, and headphones were made to paper fasteners which also held the “chassis” together.

To keep it flat, the coil was wound “spider web” style, with four taps for tuning. Blobs of solder were left exposed, and a “crocodile clip” was used to make the connections.

The whole radio could be mailed for six cents.  The schematic is shown below:

All of the parts for this set should be easily obtainable. If you need help finding any (the most difficult to find would be the high-impedance earphone), I have sources on my crystal set parts page.

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In 1967, the publishers of Electronics Illustrated and Mechanix Illustrated presented this little one-tube receiver in a publication entitled Practical Electronics.

The receiver tuned the AM broadcast band, amateur bands, or shortwave broadcast with the use of plug-in coils wound on the bases of old octal tubes. It used a dual-triode 12AT7 tube. One half served as the regenerative detector, with the other half serving as an audio amplifier. It used an isolation transformer, making the set relatively safe to use with 120 volts.

It was set up mostly as a low-cost starter receiver for the ham, as most of the coil data was for the ham bands. However, it would also make a good SWL receiver, and coil data was given for the 31 meter broadcast band.

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HCJB grounds. Wikipedia photo. by Mschaa – Own work. Licensed under GFDL via Wikimedia Commons.

In the early 1940’s, the physics department of the University of Chicago was undoubtedly an exciting place. In late 1942, the world’s first self-sustaining nuclear reaction took place under the stands of the football stadium under the direction of Columbia Unviersity Professor Enrico Fermi.

On Easter Sunday 1940, the atomic pile had not yet been built, but the University was clearly about to be at the center of some of the greatest science of our time.  But one graduate student was about to hear a different call, and it came over the shortwave radio.

On Easter Sunday, 1940, a new radio station had just come on the air and was conducting its inaugural broadcast with a new 10 KW shortwave transmitter.  The station wasn’t entirely new, but it had just installed the new transmitter, and it now had a strong signal to North America.  That station was HCJB, the Voice of the Andes, in Quito, Ecuador.

The station had been founded in 1931 by American missionary Clarence W. Jones.  Jones had worked under Chicago evangelist Paul Rader, who had been one of the first radio evangelists, having a weekly program called “WJBT” (Where Jesus Blesses Thousands), which was carried by WBBM in Chicago.  Jones had been impressed by the radio’s ability to spread the Gospel, and felt called to establish a radio ministry in Latin America.  In 1928, he traveled to Venezuela, Colombia, Panama and Cuba, seeking a location for the station, but was unable to receive government permits in any of those countries.

Later, Christian and Missionary Alliance missionaries to Ecuador encouraged him to start the radio station there.  In 1930, Jones obtained the approval of the Ecuadorian government to begin a station,

HCJB came on the air on Christmas Day, 1931.  The initial 30-minute broadcast in English and Spanish was from a fairly respectable 200 watt transmitter.  But that transmitter was sitting on a table in Jones’ living room, with a simple wire antenna strung between two poles.  And there were only six receivers in the country at the time.

Notwithstanding its small start, the station continued to grow.  And by 1940, it was able to install the substantial 10 KW shortwave transmitter that would provide good coverage in both South and North America.  By 1941, broadcasts were expanded to include Russian, Swedish and Quichua.  Other languages soon followed.

The inauguration of the new shortwave transmitter was noted in North America.  The shortwave bands reflected the fact that Europe was now at war, and the message of peace transmitted from Ecuador was a breath of fresh air.  The shortwave editor of Radio Guide magazine made these observations in the April 20, 1940, issue:

            “The Voice of the Andes”

To those listeners tired of the eternal babble of Europe’s shortwave voices of hate and war: Turn your dials to HCJB (12.48), “The Voice of the Andes,” at Quito, Ecuador. Here, at an elevation of 10,000 feet, encircled by eleven snow-capped peaks of the mighty Andes, nestles the oldest city of the New World, one of the ancient capitals of the Incas steeped in fifteen hundred years of traditions; a city whose many white churches shelter staggering treasures in gold and precious stones; a city with winding cobbled streets, overhanging balconies, ancient archways, sunlit plazas and countless white-stone houses perched crazily on steep hillsides, their red-tile roofs, with green moss cropping out here and there in the cracks, forming vivid splotches of color against the snowy mantle of the guardian peaks.

Such a historic and picturesque setting seems indeed a fitting site for a missionary radio station whose messages are those of peace and good-will. This new 10,000-watt modern short-wave transmitter–the most powerful in South America and the only broadcast station to employ a fully rotatable antenna–stands as a tribute to the sacrificing labors of one many–Clarence Jones, a gospel missionary from Chicago, whose lifework is to minister to and teach the Andean Indians. Because of the rugged contours of Ecuador, making transportation exceedingly difficult, Reverend Jones recognized long ago the vital value of radio in carrying on his work and subsequently installed several small short-wave stations at Quito, including the former 1,000-watt transmitter of HCJB and a mobile broadcasting station which carries this active pastor’s voice to the most remote jungle and mountain tribes. The new station–a labor of love paid for by voluntary subscriptions from his loyal friends–was built by an American amateur, Clarence Moore, who is well known to hundreds of amateur friends under his call, HC1JB. The new “Voice of the Andes” was officially inaugurated on Sunday, March 24.

On the dial, HCJB (12.46) comes in above the 25-meter band and approximately half-way between the 12 and 13 megacycles figures in frequency. You will have no trouble in hearing HCJB, since its unique location and rotatable aerial make it possible for it to project strong signals into North America.

HCJB is on the air for several hours daily with Spanish programs for the benefit of listeners in the Latin Americas, but English listeners will be primarily interested in “Ecuadorian Echoes,” on from 6:00 to 7:00 p.m., and the “Friendship Hour,” broadcast nightly except Mondays from 9:00 to 10:00 p.m. EST. These all-English programs are directed specifically to North America. “Ecuadorean Echoes,” one of the most interesting programs on the air, breathes the very soul of Latin America. During this period the native music, the literature and the very lives and habits of these romantic peoples come to life and parade before the microphone. “The Friendship Hour” is a strictly good-will program consisting of classical music, old-time hymns, simple gosple messages, the reading of letters from listeners and personal messages to friends everywhere.

Among the listeners to that first program on Easter Sunday 75 years ago was University of Chicago graduate student Clayton Howard. He had received his undergraduate degree in physics the previous year from nearby Wheaton College.  He had been born in China to missionary parents who returned to the United States when Clayton was 9, in order for Clayton’s father, Charles Howard, to organize the biology department at Wheaton.

By this time, Clayton was a licensed amateur radio operator.  In the 1938 call book, he is listed as holding call sign W9KJZ.  For whatever reason, he happened to be tuning above the 25 meter band that night and heard the new station.  He later recounted that he was aware of a missionary station in South America, but knew little about it before chancing upon its broadcast that night.  He was intrigued enough to seek out Reuben Larson, one of the missionaries to Ecuador who had a decade earlier encouraged Jones to start the station.

HCJB technical staff in 1945. Head engineer Clayton Howard is in the center. (Image by by SkagitRiverQueen, Licensed under CC BY-SA 3.0 via Wikipedia.)

The name Clayton Howard is familiar to many hams and shortwave listeners.  1941 saw Howard be commissioned by his church as a missionary and accept a call to serve on the technical staff of HCJB.  Howard went on to become the station’s chief engineer, and is best known as being the on-air host of the “DX Partyline” program, which he produced and hosted for 22 years.  This program was very popular with SWL’s, as it included station reports and other listening tips.  The program always concluded with Howard offering a short segment entitled, “Tips for Real Living,” in which he shared with listeners a brief Gospel devotional message.

Clayton Howard and wife Helen hosting DX Party Line, 1970’s. HCJB photo.

The Soviets didn’t normally provide recognition to Christian missionaries, but in Howard’s case, they made an exception.  When Howard retired in 1984 and made his last DX Partyline broadcast, Radio Moscow announced that “the living legend of the Andes has retired.”

If you grew up as I did listening to a shortwave radio in the 1960’s and 1970’s, the name Clayton Howard is certainly a familiar one.  And chances are, you heard one of those tips for real living.  If you did, it was probably because on Easter Sunday, 1940, a 12.48 megacycle radio signal traveled from the Andes to a receiver in Chicago.

As a result of that Radio Signal, Clayton Howard probably never met Enrico Fermi.  He probably had nothing to do with the construction of the atomic pile under the football stadium.  If he had, perhaps Howard would be remembered today as a nuclear physicist.  But God called him elsewhere, and it appears that He made that call on 12.48 megacycles.

References

• Radio Guide, 4/20/1940, page 41.
• Clayton Howard obituary.
• Janet & Geoff Benge, Clarence Jones:  Mr. Radio.
• HCJB at Wikipedia.
• HCJB website (Spanish).
• Clayton Howard at Wheaton College.

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Modern Mechanix, June 1939.

In 1928, WBBM in Chicago and KFAB, then in Lincoln, Nebraska, both operated on 770 kHz with 5000 watts.  And they both carried the CBS network at night.  They generally coexisted well, but there was a problem for listeners, mostly in Iowa, who were equidistant from the two stations.  Both stations would come in equally strong, but interfere with one another.  These listeners complained to CBS, and the two stations worked at solving the problem.

Eliminating any heterodyne (the squeal caused by two signals on very close frequencies) was an easy enough problem to solve.  The two stations simply needed to make sure that the transmitters were exactly on the same frequency.  But there was another problem.  The signals from the network came by telephone lines, and those signals travel at approximately the speed of light.   Since Lincoln was 500 miles further away from New York than Chicago was, the program reached Lincoln about 23 milliseconds later than it reached Chicago.  Therefore, the two stations weren’t transmitting the exact same program.  KFAB was sending out the program with an additional 23 millisecond delay.  (When a different phone line was used later, the delay grew to 35 milliseconds.)

This caused a problem for listeners in Iowa.  The signals from Lincoln and Chicago traversed the airwaves to Iowa in the same amount of time.  But since the Lincoln signals started with a built-in delay, the effect in Iowa was that the there was an echo effect when listening to CBS on 770.

The stations solved the problem in a number of ways.  First of all, WBBM paid KFAB to sign off at 10:00 PM, after the end of network programs.   After 10:00, WBBM had a clear channel as far west as its signal would go.  The two stations also coordinated their station ID’s so that one announcer was not talking over the other.  But the biggest problem to solve was the delay.  To solve the problem, WBBM had to delay the network feed.  With digital processing today, this would be a trivial problem to solve.  But in 1928, it was a major engineering challenge.

The WBBM engineers eventually came up with an electronic solution involving 19 stages of filtering, equalization, and amplification.  A series of filters, consisting of a capacitor and inductor, were carefully chosen.  Each filter attenuated one frequency range, but also introduced a delay.  Since they didn’t want the attenuation, the equalization was needed to restore the audio to its final form, and the amplification was needed to make up for the loss in the filters and equalizers.

But until that system was designed, WBBM engineers came up with a Rube Goldberg solution that worked amazingly well.  The speed of light is about 300 million meters per second.  But the speed of sound is about 1080 feet per second.  To generate the necessary 23 millisecond delay, sound would need to travel about 23 feet.  So the WBBM engineers procured a 23-foot section of lead sewer pipe, mounted a speaker at one end and a microphone at the other end.  The sound was simply fed through the pipe before going on the air.

The system wasn’t perfect, since echos from the microphone reflected back, adding a new echo effect, what they were trying to get rid of in the first place.  But this echo was solved by wadding fabric into the pipe.  Close to the microphone, this consisted of gauze.  Closer to the speaker, thicker material was needed.  Fabric from a pair of overalls belonging to one of the staff turned out to fit the bill, and they were stuffed into the pipe.

The result was a very high quality audio signal, with a dynamic range of 100-5000 cycles.  Eventually, broadcast standards called for slightly better audio, and the electronic system using filters was used.  But for a time, WBBM’s programming passed through 23 feet of sewer pipe before hitting the airwaves.

References

• C.B.S. Robot Timer, Radio News, June 1938.
• Modern Mechanix, June 1939.
• WBBM Radio Yesterday and Today.

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Eighty years ago this month, March 1935, Radio Craft magazine featured this one-tube broadcast radio that could be built for a dollar. The only manufactured radio part was the type 30 tube, which ate up 75 cents of the budget. Everything else was scrounged from household goods. The author reported receiving a station in Dallas, 1500 miles away from his location, the first night.

The two fixed condensers were made of tinfoil and waxed paper. The filament condenser consisted of 36 feet of 36 gauge wire wound on a spool. The grid leak condenser, which would probably be about 1 megohm, consisted of a pencil mark on a piece of wood. The tuning condenser consisted of two metal plates separated by celophane. The tuning coil was home wound on a cardboard form, and the tube socket was four paper clips.

The diagram of the completed receiver is shown below.