How A Spark In Hartford Ignited Ham Radio Across America


On May 18, the American Radio Relay League celebrated its 100th anniversary. That’s the largest association of ham radio hobbyists in the United States, headquartered in Newington, Connecticut.

Earlier this month, I went for a visit, learning about “spark gap transmitters” and why ham radio operators are called “hams.”

Ham radios don’t use transmission wires. They use nature’s built-in phone line: the ionosphere, reflecting speed-of-light signals from radios off the atmosphere, which can carry those messages thousands of miles.

Hams operate in a designated area of the radio spectrum. Think of it as a “national park” in the ether; a space set aside for hams to talk with each other and share important information during emergencies, when phone lines and cell towers can be unreliable.

To understand why hams are called “hams,” I met up with Sean Kutzko, a radio operator with the ARRL. He told me there are a lot of stories about how this name came about, but here’s the most widely accepted version:

The folks that participated in amateur radio at that point in time, the experimenters, were looked down upon by the professional telegraphy operators of the day. They were deemed to have a poor fist. If you have a poor fist, you’re not a good sender of telegraphy. So those people became known as hams, and that seems to have just transferred over to the hobby.  

Ham Radio’s Hartford Connection

This all goes back to this guy, Hiram Percy Maxim, who was ultimately one of the co-founders of the ARRL. Maxim was an inventor who came from a family of inventors. His father invented something called a “Maxim machine gun,” and his uncle developed an explosive called “Maximite” (they liked putting their name in their products).


Hiram Percy (pictured above with amazing hair) also came up with a lot of cool ideas. According to his obit in The Hartford Courant, he spent much of his life thinking of ways to abate modern noise. He invented a silencer for guns and went on to develop silencers for diesel and gasoline engines.

Percy also dabbled a lot in amateur radio. As Kutzko explains, a meeting of the Radio Club of Hartford in 1914 would change ham radio history forever. Maxim told the club he was trying to send a message from Hartford to Springfield. Kutzko picks up the story:

He was having difficulty doing so. He knew an amateur operator about midway between Hartford and Springfield, Mass., which is only about 60 miles … so he gave his message to the station midway. That was what sparked the notion of having relay stations set up around the country, and was how the American Radio Relay League was born.  

What’s A Spark Gap Transmitter?

Today, we think of ham radios as kind of elaborate setups (they don’t have to be). Early ones were simple machines called Spark Gap transmitters. Here’s a picture:


Hiram Percy Maxim used a spark gap transmitter called “Old Betsy,” which is still housed at the ARRL in Newington. Here’s what these transmitters sound like:


The technology dates back to the late 19th century. Early versions worked like this: two conducting electrodes placed close together, separated by air. When you send an electrical current through one of them, the current will eventually jump the gap and “zap” the other side.

When it does that, electromagnetic waves are released into the radio spectrum. Some energy also gets released as light and sound, which gives us that “spark” sound.

Bob Allison, a senior test engineer at the ARRL, explained spark gap transmitters using an everyday example:

If you ever listen to AM radio, and you turn a light switch on and off in your house, you’ll hear a little buzzing sound. The switch momentarily has a little arc across the contact — a little spark — and you’ll hear that popping noise in your AM radio. 

Early spark gap transmissions were just a lot of transmitted pops, which were all you needed if you’re sending Morse code. 

How well (and how far) those pops traveled took a long time to perfect, and involved smart folks like Nikola Tesla and Guglielmo Marconi. Marconi, the father of radio, was the first person to send a radio signal across the Atlantic in 1901. Here he is pictured with an apparatus similar to the one he used. 


Allison said Marconi had financial incentives to develop this technology. He was was looking to bypass landline telegraph systems in order to come up with a wireless system he could use to charge money to send signals. As a result, he developed bigger sparking apparatuses, better antennae, and ways to detect those electromagnetic waves.

Allison told me about one of those ways to detect electromagnetic waves, a receiver device called a “coherer” that Marconi used. It was developed by an Italian physicist in the late 19th century. Allison described it:

It’s metal filings: nickel; sometimes iron. When a radio wave is detected, the metal filings will kind of stand up and align themselves in a direction, which allows the filings to conduct electricity momentarily. You’ll hear a click in an earphone because of that. 

To shake the filings back up, a bell tapper (pictured below on the left) would tap the side of the glass container and loosen up the filings every time the headphones clicked. The operator would then wait for the next impulse to come in. 


Allison said spark gap transmitters were used all over the place. Hams built their own, and sailors used them a lot on their ships. In the early days, their signal strength was limited, but Allison explained that the transmitters did have practical applications for boats coming in to port: 

It would only go maybe ten miles, 20 miles or so. If you’re a lighthouse tender, or you’re on a lightship, you could radio back to shore, or radio to another ship. That was convenient at the time. 

Later on, a more modern spark gap transmitter called a “rotary gap" was placed on board the Titanic. By the 1920s, Allison said spark gap technology was falling out of use. Efficiency of these devices was poor, the signals they sent out were very broad, and they made inefficient use of the radio spectrum. 

Hams moved to newer technology, and the spark gap units actually got outlawed shortly thereafter. It’s still legal to build one, but they’re illegal to operate in the U.S. 



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