Avionics News July 2018 - 20

HANDY HANDHELDS

Continued from page 19

ILS capability and robust," Ranly said. "But it's not the
best choice for everyone."
For aircraft use, avionics shops and handheld
manufacturers almost universally recommend the use
of an external antenna - as opposed to the handheld's
antenna, enclosed within the aircraft structure.
Chuck Gallagher, who runs Cincinnati Avionics - a
division of Sporty's Pilot Shop - offered these insights
on adding an antenna for use of a handheld transceiver
in the cockpit.
"Putting an antenna on top wouldn't make much
sense for communication with ground stations - unless
you were trying to contact clearance delivery."
And even then, the clearance delivery frequency
would need to be on the same airport or have a repeater
close to the airport where the handheld is being used.
Gallagher cited two preferred options for giving an
airplane an external antenna for a handheld.
"Sometimes we'll mount a comm antenna on the
belly and run the cable up from there to where the
handheld is, or can be plugged into the coax," he said.
"That give the best performance because it's basically
line-of-sight to stations on the ground and most other
aircraft."
The second method involves using the existing
antenna of a second comm radio. "Other times we use
the No. 2 comm antenna and a (signal) splitter to cable
that antenna through to the handheld," he added.
That means using one radio or the other, rather than
both - but it also avoids the need for mounting another
antenna, top or bottom.
One other option emerged from discussions with pilots
of ultralights, some experimental aircraft and some lightsport aircraft: An antenna suction-cupped to a window
or panel and connected to the handheld via an extension
cable.
Some EAB and ultralight pilots opt for a morepermanent mount on a hard surface underneath the
aircraft - or buried within a wingtip.
Whatever solution an operator selects for giving a
handheld a better antenna, one of the basics of antenna
tuning always apply: tuning the antenna to achieve the
lowest-possible standing-wave ratio.
Using an SWR meter to set the antenna length not
only helps assure maximum performance from the
handheld - commonly rated at 5 watts PEP - but also
helps protect the power transistors from damage or
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avionics news

july

2018

premature failure, outcomes possible when SWRs are
left too high.
Dealers can help prospects shopping for a handheld
transceiver by digging into the prospect's usage plans
to help them match their needs to the capabilities of the
radio.
But not all handhelds offer comparable features.
Pilots considering adding a handheld - or upgrading
to a newer, more-capable one - should consider the
features set when shopping for one of today's pocketsize wonders.
Here are a few features common to virtually all the
handhelds on the market today.
General features, desirable and useful
In general terms, handheld radios come with some
limitations.
For example, while aviation panel-mounted
communication transceivers range from 6 watts to 16
watts of transmitting power, and in some cases higher,
handhelds tend to top at 5 watts.
For use as an airborne transceiver, the common
adjustment involves adding an auxiliary antenna to
the aircraft that the handheld can plug into, generally
increasing transmission range and audio clarity above
the integral antenna transmitting from inside the
aircraft.
Integral microphones and speakers vary in quality
and clarity but generally work well outside an aircraft's
cabin.
But for use as the main comm radio in a flying
aircraft, a headset adapter and/or external speaker and
mic offer improved performance - important as much
for the people listening as for the person transmitting.
And a push-to-talk switch Velcroed to the stick or yoke
can simplify operation.
Power sources vary, with some models providing
higher performance lithium-ion rechargeable batteries
while others use conventional AA batteries, either
rechargeable or disposable.
Some provide a power input cable for plugging the
radio into the aircraft's electrical system through an
adapter - such as a cigarette-lighter socket.
Regardless of the power source delivered, for use
in the field or in an aircraft, a second or even third
power supply is highly recommended by virtually every
manufacturer - even when normally powered by ship's
electricity. That means a spare (or two) battery pack for
the handheld.
Another common feature - and one of regular use by

Table of Contents for the Digital Edition of Avionics News July 2018