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. Transceiver2. 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

ICOM IC-7000 has large display and a separate control head.

Kenwood’s TS-480 is available in a 200 watt version

Alinco DX-70 THHF+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 AntennasAdvantages

• 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 AntennasDisadvantages

• 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 LoadedMulti 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 CatchersAdvantages

• Very effective center loaded antennas.

• Large coils results in Hi “Q”.

• Can be tapped to use on multiple bands

Bug CatchersDisadvantages

• 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 auto-tuner for use with many ICOM radios

ALINCO EDX-2for 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.

Copper strap used to make a good bond. The paint was scraped away and an

antioxidant paste applied at the points of contact.

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.

An Example Of Bonding

Copper braid bonding the door to the door jamb.Connectors are crimped and soldered and held with screws and star washers.

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.

Battery post extensions make accessory cable connections neat and safe.

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 from 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.

• Venting explosive gasses may also be necessary with an auxiliary battery.

Grommets and conduit protect wires.

Cable ties keep

things neat.

A neat and professional installation protects wires 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 RadioThe 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

http://www.arrl.org/tis/info/HF-Mobile.html

http://www.arrl.org/news/features/1999/11/05/1/

http://www.k0bg.com/

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

w3iz@arrl.org