By KE4WMF (Bicycle Mobile)
Feature Article,
February 1998.
RIDING THE AIR WAVES
By
KE4WMF (Bicycle
Mobile)
Feature Article,
February 1998.
Can bicycling and Amateur Radio coexist as one activity? Absolutely! Bicyclists often choose to ride their bicycles in order to exercise, seek adventure, save fuel, and avoid stop and go traffic. Amateur Radio operators often have ham radios in their automobiles for emergencies and so they may operate them outside the confines of their homes. There is no reason why someone cannot enjoy a good bicycle ride while having the benefits of Amateur Radio. Here is a little about myself, and how I integrated my two favorite pastimes:
I joined the United States Coast Guard in 1986 and bought my first road racing bicycle in 1987. I was a licensed road racer and I've always been a fast recreational rider, averaging about 500 miles per month. Now I prefer to log my miles doing organized rides, commuting to and from work, and exploring off-road areas. I still have my old racing bike, but I mostly ride my TREK Y5 full-suspension all-terrain bicycle. Also, my wife and I ride a tandem bicycle.
I began Amateur Radio study
while stationed aboard a Coast Guard cutter. Since I'm trained in radar,
computer, and digital circuitry repair, studying for the test was not too
difficult. I received my Technician Class license in March 1995 and bought
a YAESU FT-11R 2m handheld transceiver (HT) to use during the morning and
afternoon commutes. As spring approached, I started riding my bicycle more
often. Soon, I was making the 22-mile round trip commute to and from work,
just as I always had when the roads were ice-free. Then the thought occurred
to me, "Why should I stop talking on the radio just because I'm on a bicycle?" I began carrying the HT with me; but the rubber duck antenna just wasn't
performing well enough. That's when a series of modifications began.
My first modification was to upgrade the antenna. Since about 80% of my hamming is done from a bicycle, I've learned a few things about what is important when working bicycle mobile. I believe the most important element of a bicycle mobile station is the antenna, especially one that does not require a groundplane. Here is my station now, starting with the antenna: |
My primary antenna is a LARSEN NMO-150HW 1/2-wave. Copper-wire "J-poles" are great, but they're a little awkward on lightweight bicycles (especially off-road) and they take a real beating in the woods. I find the Larsen to be light and nimble, easily flexing around low tree branches and other obstacles in the woods. The Larsen does not require a groundplane; so the mount was made as small as possible. Although the 5/8-wave antenna is considered an axiom for mobile applications, the 1/2-wave is much more effective, yielding SWR readings below 1.3:1 across the band.
 The antenna is mounted
to an aluminum support that I fabricated from four feet of 3/16-inch solid
aluminum rod to fit to the water bottle mount behind my seat. I used a vise
and vise-grips to bend the rod in the desired shape. Since welding such small
aluminum is very delicate work, I chose to use GOOP Household Adhesive to
hold the pieces together. Unlike superglue or epoxy, Goop is not rigid when
dry. Therefore, the mount has held up well under various conditions. Several
coats of gloss black paint finished the job and hid the glue. The antenna
mount is secured to the seatpost with special aluminum mounts that are designed
to hold a water bottle bracket to the seatpost.
Moving forward, one or more PANASONIC gel cells are kept under the seat. Currently, I prefer to carry two 6-volt 4Amp hour (Ah) batteries so I may operate my HT and the headlights at the same time (more on why I carry two later). Obviously, I don't run the headlights full-time, so I actually have plenty of HT use available. I get 2 watts from my HT this way, which is usually enough. Another reason I prefer 6 volts is because it can be put straight into my HT without using adapters. The problem with adapters on my station is that my HT operates on 9.6 volts instead of 12. Therefore, I have to use an adapter to convert 12 volts into 10 volts. The conversion process uses more current than the HT itself... even when the HT is turned off! For example, the adapter alone draws 12mA with the HT disconnected (18mA with the HT connected, but turned off). The HT and the adapter together draw 60mA (squelched). And if I don't unplug the adapter when it's not in use, the battery will slowly discharge. By plugging 6V directly into the HT, the current drops to 0mA with the radio off, and only 15mA with the radio on. With 6-volt batteries, I may sacrifice a few watts, but I eliminate the battery-consuming voltage adapter. Why do I carry two 6-volt batteries? Sometimes two watts is not enough. Therefore 12 volts and the adapter become necessary. I've designed a switching circuit (described in another article, Doubling Your Fun While QRP) that allows me to switch two batteries from series to parallel. Also, the adapter is bypassed during 6 volt operation. Using this method, I experience maximum battery conservation but still have the ability to use five watts if needed. |
 The HT rests in a homemade
handlebar mount, created by gluing and screwing the mounting pieces of a
bicycle headlight to a small carved up RADIO SHACK project box. Any light
will do, as long as both the piece that mounts to the light and the piece
that attaches to the handlebar are available. Again, Goop was used to secure
the mount to the handlebar. Initial tests revealed that superglue cracked
during heavy vibrations off-road. Goop has not failed yet, even after crashes.
Since I ride on rocky trails, I have reinforced the HT mount by adding thick Velcro
straps and special cutouts so it HT will not fall off the mount. The finished
product is a fully adjustable handlebar mounted HT mount with full keypad/display
access and quick-release features.
The final part of my ham setup is an SPM-400 boom speaker/mic, by ADI/PREMIER COMMUNICATIONS. It rests on my ear, so it does not interfere with my helmet. The PTT (press-to-talk) switch is very small, so it can be mounted almost anywhere and it gives me hands-free operation. The combined weight of the bicycle and the ham rig is just less than 35 pounds. My design's only drawback is the equipment's vulnerability to damage in a crash. Since I usually lay the bike on its side in a crash, the equipment should be adequately protected by the handlebar ends (A BRUTAL CRASH proved that I am more susceptible to broken parts than the radio or bicycle). |
Other equipment
includes a REALISTIC PRO-39 200-channel programmable handheld scanner, a
CYGO LITE 20-watt dual halogen headlight system, a TREK Radar multifunction
cyclocomputer, and a DELTA pneumatic horn (115dB). My goal is to take my
bicycle mobile station beyond simple conversation and into some sort of community
service, such as search and rescue, or event coordination. Even without community
services, I can still report traffic accidents and other emergencies before
most people can get to telephones.
Overall, I'm very happy with what I have. I'm sure I don't have the greatest station in Amateur Radio. I've traded some performance for weight and size. Still, I'm able to use just about any 2-meter repeater within 10 to 15 miles (I use some from 40 miles <65 miles is my 2W record>). I think it's interesting that I was able to take two hobbies and combine them into one. Fellow cyclists have to agree that I am one of the safest cyclists to ride with because more help is just a quick call or telephone patch away. One thing is certain: I can't complain about the performance I'm getting from a BICYCLE station! |
73,
Click here to read about my longest bicycle mobile bike ride, the Armed Forces Cycling Association's Tour of the Southeast.
Click HERE to read about BICYCLE MOBILE HAMS OF AMERICA, a national club for Bicycle Mobilers.
E-mail Scott