BELOIT, Wis. (AP) — Amid buzzing radio feedback, amateur radio operator Chuck Bell quickly tunes into a far-off signal, listening for a return as voices whir in and out of range.

"You pick up whatever the person on the other end is sending," he told the Beloit Daily News . "It's going to blow your mind here in a minute."

Bell, whose office is filled with radio units, computers, monitors, maps and FCC notices with old log books piled high, comes alive like most amateur "ham" radio operators do as they work.

Some may see the far-off radio contacts as strangers, but to Bell and other residents like him that live near the Wisconsin state line, amateur radio is more than a hobby — it's a professional relationship built on camaraderie.

Radio communication between amateurs started just after the turn of the 20th century, but the craft is more vibrant than ever.

An estimated 2 million people are on the airways worldwide, according to the American Radio Relay League. About 830,000 amateur radio stations are located across North, Central and South America alone.

Amateur radio exploded in the United States after the FCC removed a requirement that was a barrier for most: Morse code requirements for all station licenses (although Bell and others look to preserve the code element of amateur radio).

The hobby covers a huge spectrum of participants — from hobbyists, like Bell, who runs a local network in Rock County, to those who are competitive.

Janesville resident Robert Urban makes long distance contacts to countries all over the world through a process known as "DX'ing."

To date, Urban has made contact with 320 entities in different countries.

Both Bell, a Beloit native, and Urban are members of the Greater Beloit Amateur Radio Club. Urban also belongs to the Madison DX Club, a group of radio operators that embark on expeditions all over the world to set up amateur radio stations. The Madison club has sent members to the Antarctic and the South Sandwich Islands. Soon the club will send members to Baker Island.

Bell became interested in amateur radio in the mid-1960s, getting his first license to send and receive messages in 1974. The former Beloit Corporation electronic tech has always been tinkering with electronics.

"I was so nervous," Bell said. "I had my station all set up and it was my turn to say something back to him (another operator). I was shaking like a leaf. Ever since then I have loved it."

Over the years, Bell helped other radio operators as they would try different techniques to log contacts. On one such occasion, he helped a friend conduct a "Moon Bounce" where signals are bounced off the Moon and the user deciphers what comes back.

"I couldn't believe it," Bell said. "We were bouncing signals off the Moon. You can use that and multiple satellites, too. We did it because we could. It never used to be this easy. It hasn't always been this sweet."

Urban is a research professor in the surgery department at Chicago's Rush Medical Center. He moved to Janesville six years ago.

Although his relationship with amateur radio started decades ago, it wasn't until nine years ago he picked the hobby back up.

Nowadays, Urban's home allows him to build a strong station, with his office including multiple radio transceivers, with capabilities that allow him to decode (if he wanted to) digital forms of communication that sound like unpleasant noise to the untrained ear.

Urban's interests lie in using the most challenging frequencies, from very low to very high frequencies, to make long-distance contacts. Urban even harnesses a technique known as "Aurora propagation," where he will point his antenna north to the Arctic circle to beam signals from Janesville to the Aurora Borealis, using the ionosphere to make connections.

Long before his deep dive into challenging frequencies, Urban recalls one of his first long-distance contacts.

"I woke up suddenly at 2 a.m. and something told me to get on the air," Urban said. "I was on, and back came the voice of an Australian."

Both Bell and Urban said most radio operators stay away from politics and religion, but often talk about other things to learn bits of information from a hobbyist far away.

They said participating in the annual ARRL Field Day, which is the most popular on-the-air radio event in the U.S. and Canada over the weekend of June 23, was important for the Beloit club. Around 30 members camped out at the Janesville Fire Department training center to set up and make contacts with other radio operators celebrating the day.

"Some treat it as a contest," said BARC President Brett Johnson. "Other groups use the opportunity to practice their emergency response capabilities. It's an excellent opportunity to demonstrate amateur radio to the public."

Johnson said the Beloit club makes around 1,300 contacts on field day and the group has worked out of the Janesville Fire Department training facility since 2011. Club members take shifts on the 24-hour schedule.

"We all love what we do out here," Johnson said.

Before anyone can get started on the air, all operators must be licensed and know the rules to operate a radio legally. Federal licenses are good for a decade. To find a certification class and to schedule exam sessions or to view frequently asked questions about amateur radio, visit arrl.org/getting-licensed.

The club's website is rockhamradio.com/gbarc.

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Information from: Beloit Daily News, http://www.beloitdailynews.com