HF Mobile
Installation and Operation
Why HF Mobile?
• HF Bands are used for Long and Medium
haul communications. VHF & UHF for
short range or local communications.
Why HF Mobile?
• With today’s modern compact transceivers
it is possible to have portable HF
communication in our vehicles.
Components Of A Mobile Station
1. Transceiver
2. Antenna System (radiator + matching network)
3. Power Source
Transceivers
There are many HF transceivers on the
market made specifically for mobile or
portable use.
Transceivers
• Units designed for mobile work usually
have easy to read displays.
• They should be mounted so that they do
not affect the driver’s ability to safely
operate the vehicle.
Yaesu offers
many models for
mobile operating
ICOM has its IC-706 and IC-703
(QRP) models
Kenwood’s TS-480 is available in a
200 watt version
Alinco DX-70 TH
HF+6m All Modes
Antenna Systems
• Mobile antenna Systems are comprised of a
radiator and a matching network.
• Mobile antennas have a low impedance,
therefore, a matching network is required.
Antenna Systems
• Systems can be mono-band or multi-band.
• Multi band systems can be tuned from inside the
vehicle while in motion or from outside the
vehicle when stopped.
Antenna Systems:
Good, Bad and Ugly
•
•
•
•
All systems have some sort of loading.
Center loading is best.
Base loading is least effective
Because of their skinny coils, helically wound
antennas are a compromise of the other two
designs.
SWR
• A good SWR is not an indicator of an effective
antenna system.
• Click your heels and say this three times.
• Think of a dummy load; it has a good SWR but is
not an effective antenna.
BIG NOTE
*
*An entire program can be had just on the
discussion of antennas. All mobile antennas are
a compromise of some sort and much
consideration should be given to safety and the
type of operating that is being done, as well as
spouse appeal.
End of Big Note.
Multi Band Antennas
1. Motorized
2. Automatically tuned
3. Manually tuned
Center Loaded Antennas
Whether motorized or manually
tuned, these are by far the most
effective type of mobile antenna.
Motorized Antennas
• Commonly called “screwdriver” antennas
because the first designs used cordless
screwdriver to drive the screw that adjust the
coil.
• Uses a motor to move a large coil up and down
to obtain resonance.
• System consist of the large coil, whip radiator,
shunt coil at feed point and a control unit
Motorized Antennas
Advantages
•
•
•
•
Multi band.
Can be tuned from inside the vehicle.
Hi “Q” Very effective antenna.
Computerized control units can be added
for quick band changes.
Motorized Antennas
Disadvantages
• Large and heavy; requires strong
mounting and support brackets.
• Hi “Q” make tuning on low bands very
touchy.
High Sierra motorized antennas
Lil Tar heel motorized antenna
The Yaesu ATAS-100 Active
Tuning Antenna System
provides HF/VHF/UHF
coverage with automatic
motorized tuning. Utilizing
control signals from the
transceivers microprocessor
received via the coaxial cable,
the ATAS-100's internal motor
adjusts the radiator length for
best SWR.
Manually Tuned Center Loaded
Multi Band Antennas
• Some types use taps to tap the coil at a
resonant point.
• Other designs use multiple resonators or
change resonators on a single mast.
Bug Catchers
Advantages
• Very effective center loaded antennas.
• Large coils results in Hi “Q”.
• Can be tapped to use on multiple bands
Bug Catchers
Disadvantages
• Large and heavy requires strong
mounting and support.
• Band changes have to done while
parked.
Large coil and center
loading make the
Bugcatcher an excellent
performer. This unit is
shown with a capacitance
hat.
Capacitance Hats
• Loss resistance is lowered by removing turns in
an inductor coil.
• This is then compensated for by adding
capacitance above the coil.
• The more capacitance that is added the less
inductance is needed for a given frequency.
CPU Controlled Automatically
Tuned Multi Band Antennas
• Uses a CPU controlled matching network and
a whip antenna.
• Can match almost any frequency.
• Some models are capable of matching over a
million LC combinations in less than a second.
CPU Controlled Automatically
Tuned Multi Band Antennas
• System can be made low profile.
• Internal memories save settings an allow
quick band changes.
CPU Controlled Automatically
Tuned Multi Band Antennas
• When used with a loaded whip designed for the
tuner these systems can be extremely effective.
• When used with a 8 ft. whip the system is less
effective than loaded whip or center loaded
systems.
Interior view of
YAESU FC-40
CPU controlled
remote tuner for
FT-897 & FT-857
radios
ICOM AH-4 CPU
controlled autotuner for use
with many ICOM
radios
ALINCO EDX-2
for USE exclusively
with ALINCO DX-70T,
DX-70TH, DX-77EQ,
DX--77T, DX-701 and
DX-707
SGC makes an
entire line of reliable
CPU controlled
auto-tuners that will
match almost any
radiator with any
radio.
SGC’s QMS
system is rugged,
mounts on any
vehicle and
includes the CPU
tuner and loaded
whip antenna.
Mono-Band Antennas
•
•
•
•
•
Operate on a single band.
Can be effective.
Can be made low profile.
Can be easily mounted.
Inexpensive way to enter into HF mobile.
Good results can be
had with mono band
antennas. These
“sticks” can be
easily mounted and
are lower profile.
Antenna Mounting
• Which ever antenna is used the mount
has to be solid, strong and safe.
• No sharp edges or protrusions that could
cause injury.
• Anything flying off a moving vehicle can
be deadly. Safety first.
• Obey DOT laws.
Custom Heavy Duty Mount
Notice the
heavy braided
ground strap
added to this
custom mount
ensuring a
good bond to
frame.
Custom Heavy Duty Mount
Don’t Be Afraid To Drill A Hole
Mounting Alternatives
Mounting Alternatives
Grounding
• A good solid ground connection to the vehicle
frame is necessary for good antenna
performance.
• Make ground connections as short as possible
and to bare metal.
• Ground connections can be weatherproofed
with undercoating spray.
Bonding
• Bonding is connecting together loose or moving
metal parts of the vehicle with grounding braid.
• These areas are doors, trunk and hood lids,
mufflers and exhaust parts, and any other
areas where metal parts may rub.
• Rubbing metal parts can cause excessive noise
in the receiver.
Power
• Power should be taken directly from the
vehicle’s battery.
• Both positive and negative leads should be
fused at the battery. If there is a fault anywhere
after the fuse the fuse will do it’s job and break
the circuit.
Both leads
should be fused
at the battery to
prevent fire.
Power
• Drawing power directly from the battery helps
eliminate noise.
• All leads should be 10 ga. or larger stranded
wire and be kept as short as necessary.
• Protect wires with rubber grommets where they
pass through the firewall or any metal.
Power
• Flexible conduit and wire ties make the job neat
and also protect wires form accidentally being
cut or shorted.
• If using an auxiliary battery, make sure that it is
securely mounted with proper electrical
connections and change over charging circuits.
Grommets and conduit protects wires. Cable
ties keeps things neat.
Flexible conduit
and wire ties
keeps all wires
dressed and
neat.
Wires and cables
Keep all wires and cables as concealed
as possible.
Not only does it make the job look neat
but, it also protects them from damage
and prevents anyone from tripping as
they enter or exit the vehicle.
Mounting The Radio
The radio should be mounted in such a way that
it does not interfere with the driver’s ability to
safely operate the vehicle.
Period.
Mounting The Radio
Say it again.
The radio should be mounted in such a way that
it does not interfere with the driver’s ability to
safely operate the vehicle.
Period.
Mounting The Radio
The mount should…
1. Be secure.
2. Not obstruct the driver in any way
3. Keep the unit within easy reach and view.
4. Allow proper air flow and not be in a heat
source such as heat ducts.
Mounting The Radio
Unsecured objects in a vehicle are potential
hazards in an accident.
They can be thrown about, hitting the
occupants with deadly results.
Mounting The Radio
A lot of the mobile HF radios today offer a
detachable remote control head that allows to
“face” of the radio to be mounted in a safe and
convenient location while the main unit is
mounted out of the way under a seat or in a
trunk.
Pedestal
mounts work
well in pick up
trucks…
…or SUVs
An aftermarket visor
shelf makes a
convenient and safe
mount for this ICOM
IC-706 control head.
Gooseneck allows
control head to be
adjusted.
Control head of this
YAESU FT-100 is
mounted safely and
securely and allows
the driver to view it at
a glance.
YAESU FT-857 control head mounted on
gooseneck and radio mounted under passenger
seat. A neat and secure installation.
Noise
• Grounding and shielding should eliminate most
noise in your receiver and on your transmitted
signal.
• Ferrite on speaker leads and other leads to
electronics and CPU modules can remedy RFI
in the vehicle.
Noise
• Previously mention bonding of metals parts can
prevent unwanted receiver static noise.
• A large capacitor from the positive lead to
ground will eliminate AC noise on DC power
cables.
Noise
RFI to your vehicle can be a problem. Some
fuel pumps or other devices have been known
to shut down in the presence of strong RF
signals.
Consult your vehicle manufacturer for any
Technical Service Bulletins (TSB) regarding
these issues.
Publications
“Your Mobile Companion”
http://www.arrl.org/catalog/?item=5129
Publications
ARRL Handbook
http://www.arrl.org/catalog/?item=9280
Publications
ARRL Antenna Book
http://www.arrl.org/catalog/?item=9043
Resources
• ARRL on the web:
http://www.arrl.org/tis/info/HF-Mobile.html
http://www.arrl.org/news/features/1999/11/05/1/
Contributors
Thank you to all who supplied pictures of their
mobile installations:
AB1ER, N1RWY, W2WJO, K3CAV, W3IZ,
N5PR, K6OWL, W6PW, WØWEB
Contact
Norm Fusaro, W3IZ
ARRL Affiliated Clubs/Mentor
Program Manager
225 Main St. Newington, CT 06111
860-594-0230
[email protected]