Amateur Radio on the RV trail
By J.M. Huckabee, AA5BU
Radio operation from your recreational vehicle is the greatest experience
the radio amateur will ever know! It's like a continuous Field Day. You
have your choice of location, emergency power, freedom to avoid constrictive
problems and an antenna height to a mountain top. It is the "Crown
Jewel" of Amateur Radio.
My wife and I have been on the RV radio circuit about 100 days per year
for more than a dozen years. First by motorhome, and later by trailer.
We prefer the trailer and a big diesel-powered tow vehicle. The diesel
makes more electric power at idle speed than is ever needed - and diesels
do not create electrical noise!
What type of Ham gear is needed? Almost anything that is powered by 12
VDC is fair game. Other considerations are equipment size and available
space.
What antenna can be used? Again a simple answer - anything that works
on an automobile, works better on the larger size of the RV. And anything
that works as a temporary antenna at home also works with the RV.
I use three transceivers - a Yaesu FT-747GX, a Kenwood TS-140-S and an
Alinco DX77-T. Each are about the same size and weight, operate the HF
bands and are rated at 100 watts output. I carry one and use another one
as a spare. Give or take a few simple features, operating results are
very similar.
Personal factors may alter your choice of equipment and modes of operation.
By example, here are some items that influenced my choices: I'm 80 years
old, and my hearing cuts off at about 1,200 Hertz, which makes voice reception
difficult. To capitalize on those factors, I operate "fast-lane CW"
tuned to a note of about 450 Hertz. It's like having an extra filter built
into my brain. It's a great feature of old age!
Let's look at some pitfalls you may encounter with RV operation. Everything
runs on a battery. A 2-volt drop in battery voltage is more than most
Ham radio equipment can tolerate. Brush-type motors are poison! Switcher-type
battery chargers are equally bad! Here's my solution - the battery charger
was replaced with an MFJ 35 amp power supply. Vent fans were replaced
with fans that use brushless motors. Avoid running the water pump during
reception. Place your gear near the vehicle battery, and set the power
supply at about 13.5 volts. Your battery is always full and safe. When
powered by the tow vehicle, its charge is regulated by the vehicle. How
much operating space is needed? Really not much. I use a a table-high
shelf about 12 by 18 inches. My log book is lap-held on a clip board.
I make notes on a small pad, and transfer the information to the log.
It's a chair-side operation!
How can I get my signal to the antenna? I use a 50 ohm coax cable through
the floor. It runs along the frame of the trailer and up to the spare
tire rack, using about 35 feet of cable. Tie-wraps hold the coax in place.
How do you mount and store the antenna? Most RV's carry the sewer hose
in a hollow bumper - and that's the way to carry your antenna. My antenna
sits on a home-built lift-off base affixed to the spare tire carrier.
A PVC pipe was mounted across the back of the trailer and is equal to
the 8-foot width of the trailer. My antenna is three screw-together sections,
each 7 1/2 feet long. These are carried inside the PVC pipe. I have a
choice of 7 1/2, 15 and 22 1/2 feet of antenna length (height). I mostly
use two sections at 15 feet.
What bands will this antenna operate on? I operate 40, 30 and 20 Meters
using the 15-foot length. Here's what I do - the antenna has a connecting
lug, and the coax has a raw tip. I connect the two together with a little
loading coil and alligator clips. A coil for each of three bands are used
on the respective bands. The coils were made and adjusted with the aid
of one of the MFJ pieces of test equipment. A VSWR of 1.2:1 over a short
frequency range was achieved. Does this combination of equipment and techniques
really work? Yes! You can bet your Texas boots that it works well! And
just how well? A log of over 4,000 QSOs is the proof. For obvious reasons,
20 Meters works best, then 30 Meters followed by 40 Meters. On 20 Meters,
I commonly receive signal reports of one "S" unit lower than
the fixed station I'm talking to. On 40 Meters, it is commonly two "S"
units lower. And 30 Meters is somewhere in between 40 and 20 Meters.
I have been licensed since 1940 and this is the most fun I have with
Ham radio in years. It's truly the "Crown Jewel" of my Amateur
Radio career.
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