Saturday, 25 June, 2005

Field Day 2005

Today and tomorrow mark ARRL Field Day 2005, the annual ham radio event where we all head out to remote locations, set up temporary stations, and see how many stations we can contact.  Okay, so it's a 2-day geek fest for radio nerds.  We actually do benefit from it.  The idea is to simulate operating for an extended period in an emergency, using power other than from the commercial power lines.  Mostly that means gas powered generators.

There are many different categories of stations and many different ways to earn extra points beyond the points you get for making contacts.  There are points awarded for having an elected official visit the site, for having a press release published in the paper, making a contact via one of the amateur radio satellites, special modes, and natural power.  For the second year in a row our club's natural power source was me riding a bicycle.

I wrote up last year's experiment here.  That setup used a small Plymouth alternator to convert my pedaling into electrical power that was stored in a battery.  We charged the battery and used it to make our required five contacts to earn the 100 points for a natural power source.  There were two problems with that setup.  First, a lot of my pedaling effort was wasted exciting the field for the alternator.  Second, it just wasn't very sexy.  Pointing to a battery and saying "I charged that by pedaling" doesn't have quite the same effect as driving the radio directly from the bicycle generator.

This year my friend Steve Cowell (KI5YG) got hold of a 24 volt electric scooter motor and wired up a voltage regulator.  If you turn an electric motor, it acts like a generator.  We attached the motor to the bicycle using the same V-belt we used last year, put a 22,000 μf capacitor in-line to insulate me from the transmitter load, and attached the radio to the voltage regulator.  32 minutes of medium-hard pedaling later and we had our five contacts.  That was a whole lot easier than the hours and hours of pedaling I had to do last year in order to charge the battery.