By Dave Jensen, W7DGJ

Lately I’ve been thinking about my day-to-day use of tiny QRP radios, and I wondered how small a radio can get with today’s push for ultra-miniaturization. My research came up with two examples, but curiously they are from almost one-hundred years apart. One is from modern-day research at Harvard. and was built with atom-sized building blocks. I will contrast that radio with a tiny unit made by a ham for the 1933-34 World’s Fair. I hope you’ll find this story as interesting as I do!

Experimentation in Radio Miniaturization at Harvard

Did you know that a radio was developed at Harvard (Boston, 2016) using building blocks that were the size of two atoms? This story originates with a scientific journal, Physical Review Applied, and it describes the work done by Prof. Marko Loncar and his graduate student. Linbao Shao (now an Assistant Professor at Virginia Tech). These two were experimenting with defects in diamonds when they came across an interesting concept -- one that could be practical in the future. This work may have paved the way for biocompatible radios that will be implanted into a human body, or even used in a Venus probe where temperatures and pressure are major roadblocks to communication equipment.

The radio uses imperfections in diamonds called nitrogen-vacancy (NV) centers. To make NV centers, Dr. Shao replaced one carbon atom in a tiny diamond crystal with a nitrogen atom and removed a neighboring atom. Doing this created a system that is essentially a nitrogen atom with a hole next to it. This can then be used to detect very weak magnetic fields, including the waves used in FM radio. When this "diamond radio" receives radio waves. it converts them and emits the audio signal as red light. At this point, a common photodiode converts that light into a current, which then becomes sound through a simple transducer such as a speaker or headphone.

An Earlier Tiny Radio and the World's Fair that Introduced It to the Public

1933 was an interesting time in radio history. The '29 stock market crash had really hurt the general public's ability to go out and buy the latest technologies, but by 1933 a recovery had begun. Over the previous decade, the world had seen technological wonders such as indoor plumbing, telephone and electrical service, modern appliances, transportation and more. The average home was being transformed to include these new elements. The World's Fair, "A Century of Progress," was held in Chicago to celebrate this new consumerism and radio was an important part of that. Galvin Manufacturing had just begun to put radios into cars, and FM radio had just been invented by Edwin Armstrong.

Amateur Radio had its place at the World's Fair with a convention in August of 1933, but in order to conduct decent live QSOs it was determined that the demonstration station could not be located anywhere near the large building holding the electromagnetic displays; the noise it presented on the amateur receivers made working the airwaves impossible. As a result, hams responsible for the effort had to move their rigs to the absolute furthest point in the fair, rendering it almost impossible to find for visitors. Despite this, more than 4000 licensed amateur radio operators made it to the demonstration station, some of them traveling from DX locations around the globe. In addition, tens of thousands of citizens (non-hams) were introduced to Amateur Radio and the radio hobby through this demonstration station, W9USA.

One of the draws was a tiny radio that America's first black radio operator had built for the fair. It was, at the time, the world's smallest radio. Mr. Rufus P. Turner (W3LF) was one of those young men who had found his place in radio as a boy, and he later proved to have a large impact on the ARS and on electronics experimentation in general. In 1933, Turner was just 26 years old and he was already turning heads.

While his miniature radio appears to have been primarily a curiosity item with little lasting impact, Turner's later inventions and manuscripts proved of lasting importance to ham radio. His world's fair entry was described as "a midget radio built on a pin, just one and a quarter inches long." But throughout his career, W3LF produced rich, technical documents and books that helped thousands of experimenters (including your author). Many of these were published via Hugo Gernsback's publishing house and some still exist today on the shelves of amateur radio operators and electronics instructors at trade schools and universities. (Let me know in the forum discussion that follows if you've got a Rufus P. Turner publication in your shack.)

Turner went on to work at Sylvania in the 1940s as an electrical engineer and was an integral part of the team involved in the 1N34A germanium diode development.

Before transistors were even available, Turner published a landmark article (for Radio Electronics Magazine) called "Build Your Own Transistor" which gave radio amateurs an exact plan to follow for producing their own from his very detailed plans.

His later publications also included his wonderfully detailed insructions; one of them showed how to build crystal receivers with transistor amplifiers. Later, when commercial transistors became available, he published full plans for a three-transistor radio that came out four years before the first commericial product, the Regency TR-1. In short, without Rufus Thomas and his great material on electronics assembly, many amateurs could have been years without ideas for transistor experimentation.

The Crowds Find the Amateur Radio Demonstration Station

W9AZI, writing in a 1933 QST editorial, describes some of the wacky interactions that citizen attendees had with the volunteer operators at the demonstration station -- especially, their confusion upon signing into the station log as visitors. 

"Rather than be impolite and refuse permission to register, we allowed attendees to sign the ham register," the volunteer ham described. "The column in the log marked "Call" had them stumped, and the results in many cases were startling. Some took a look at the signature above and mixed figures and numbers indiscriminately to fill this space for their "call."  COD, FOB and BVD were also much in evidence. And one YL, after considerable thought, recorded her phone number."

As much as we might tease about the average person's knowledge of our craft, I can't help but feel that the World's Fair demonstration station had an impact -- positively -- on Amateur Radio. Is there a modern day example of a way that clubs or the League could demonstrate the value of Ham Radio to the masses? Perhaps it's through State Fairs or events that take place at the community level. 

There's a story told by the hams who worked the demonstration station at the end of the 1933 World's Fair, at the last hour of the event. It was nearly 11 PM and the building would be empty soon, ham radio equipment taken off display. That's when a stretch limousine pulled up in front of the building and let out a distinguished looking gentleman, a senator from Italy who had been visiting Chicago and the World's Fair for several days. 

360,000 people had visited the Amateur Radio exhibit. And when this last, elegant fellow stepped into the demonstration station, the two tired volunteers who had remained behind working the airwaves stopped to greet him -- even though they didn't recognize him at first. After an introduction they were proud to show Guglielmo Marconi the station equipment. The inventor inspected the transmitter and commented that it was "A beautiful piece of work." As the ham who built it was working that evening, it was likely a treat that he would remember for the rest of his life. He thanked Marconi for the nice comment, and in a self-depreciating manner said, "But it was simply built by an amateur."

Marconi looked at the two operators and replied, "But gentlemen, I am only an amateur myself."

73 for now,

Dave Jensen, W7DGJ

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