Posts Tagged ‘ic-7100’

HF Mobile, A Different Kind of Radio Shack

This is my favorite ham radio portable/mobile venue.

The Scorpion Antenna is mounted in a good spot in the rear of my pickup truck bed. Seen here at Hagen’s Cove in Perry Florida on the Gulf of Mexico in the ‘big bend area’!

Going Mobile, Rag Chews, Nets, CW, its all available and very doable when you are on the road!


Mobile HF radio adds yet another dimension to Ham Radio. This is my second go, at HF Mobile operation.

Years ago, when ‘real life’ happened to me, I had no home QTH to operate from so I bought a new (at that time) Icom 706 M II G radio.  It was a great choice. A DC to daylight rig, and its still working 15 years later. This next episode of HF mobile is greatly improved over my previous one. A good antenna at the time, was made by High Sierra. It was a screwdriver type. (the original mobile antenna’s were nick named ‘screwdriver’ because they used an electric screwdriver for moving the coil)

High Sierra no longer makes mobile antennas, but the good news is there is a good company making them in Arizona, Scorpion antennas!

Scorpion Antennas

The Scorpion antenna is a heavyweight, at 18 pounds and it needs a very robust base to hold it. Breedlove Mounts

Its the Rolls Royce of Mobile screwdriver type antennas, and not just because I bought one, it is indeed, a very rugged and carefully crafted antenna.

I’m primarily a CW op so I incorporated a touch sensitive paddle to do CW on the move or sitting still in a local park like this one at Hagen’s Cove, on the Gulf of Mexico in the ‘big bend area of Florida!’

Bayonet Adapter with Cap Hat Mast

The cap hat ‘whip’ is a 3 foot rod of solid aluminum. It shortens the overall whip. This is nice for parking my truck in the breezeway without hitting the roof.


A motorized coil is moved up or down electrically! Listening for the greatest noise, depending on the band of choice, puts me in the ball park for checking the SWR. A 1:1 ratio is easily obtainable if care is taken during installation. Bonding straps are a must. All the parts of the truck body, door, tailgate, hood, fenders and truck bed, must be bonded together to from a good RF ground. Not a DC ground, mind you, but an RF ground plane. (The ‘other half’ of the antenna’)

All the Doors Are Bonded

All the body parts of the truck must be bonded together with straps. RF flows on the surface not the cross section of a conductor, so the wider the better. Copper flashing best carries RF current but a compromise is make for braid due to continuous flexing while opening and closing doors, and tail gates.

Bonding is one of the things that separates a good installation from a poor one. I had fun with the first truck and radio set up back in 2001 but I learned a lot about mobile HF radio since then and did things differently this time.

Location, location, location! It sells real estate and its very important for HF Mobile Antennas!

What makes a good location on a vehicle?

I’ve seen many examples of HF radio antenna installations that work, but some work much better than others. Besides bonding, another good trick for a good installation is to use a very good location; the main mass of metal must be Directly under, not near, the base of the antenna. Will a bumper mounted antenna work? Yes, but one with a mass of metal directly beneath the antenna will work better.

Its simply a case of, more bang for the buck!


Positioning the bottom of the movable coil above the  truck side wall is best.

Positioning the bottom of the movable coil above the truck side wall is best.


The Scorpion antenna movable coil still has the protective bubble wrap on it in this picture.

Scorpion Antennas

Clearance is important!

The bottom of the coil must have clearance from metal objects like the side wall of the truck.

Detailed installation instructions come with the scorpion antenna. This is very important. A good installation will insure good operation.  Skimping on installation will only hurt you in the long run.


I installed an auxiliary battery in the back set compartment of the truck. Its a sealed lead acid 75 Ah battery made by Optima. I bought it trough Apex Battery.

Optima Blue Top from Apex Battery co.

Optima Blue Top 75 Ah Auxilliary Battery

Optima Blue Top 75 Ah Auxilliary Battery


I can use either the auxiliary battery or the truck battery or both at the same time, thanks to a marine dual battery manual switch.

See its picture below.

I used #4 wire to connect the truck battery in parallel with the auxiliary battery in the back seat area. This large gauge wire greatly reduces voltage drop between the batteries. For extended stays in one place, I can operate on the auxiliary battery, without running the engine. This insures that the separated truck battery will start the truck when I’m done operating.

I have not yet mounted this switch on a back board, but that is coming. I need both hands to operate the switch now and I want to be able to do it with only one hand!

Perko Switch

Dual Battery Switch in the -Both-Battery- Position

Dual Battery Switch in the -Both-Battery- Position

The business half of the IC 7100 is mounted to the floor of the truck on the hump. The battery box can be seen with a power pole connection box on top.
The control box for the IC 7100 rides up front on the center console as does the touch sensitive paddle. The microphone hands on the cup holder.

I have a Warren Gregoire headset for SSB. It features a noise cancelling microphone. Warren Gregoire Headset (no relation to me)

(Special note here; its illegal to have both ears covered with a headset in Florida while you drive.)

Its a stupid law because you can legally drive in Florida even if you are stone deaf! So that kills the reasoning for ‘listening to sirens’ on emergency vehicles!

Okay, that rant is done!  Back to the Mobile installation.

Battery Box, with Power Pole Box,-top, IC 7100-bottom

Battery Box, with Power Pole Box,-top, IC 7100-bottom


AA1IK, Using Warren Gregoire Headset 2

AA1IK, Using Warren Gregoire Headset 2
Join me on a new Yahoo Group for HF Mobile ops.
New HF Mobile Yahoo Group

Here I am using the Warren Gregoire headset. This headset has a noise cancelling mic so its a good fit for mobile HF radio. SSB is a new thing for me. I’ve been a CW op, for most of my ham life. I’m having a great time meeting new folks all around Florida on 40 Meter SSB. Ham radio has lots to offer and I’m glad I have not yet exhausted all the possibilities. I have not forsaken CW, but SSB is a fun mode, as I’m sure many of you already know.

The IC 7100 is a two part radio. You saw the ‘business end’ in a previous photo. This photo shows the control head and the touch sensitive paddles Touch Sensitive Paddles They are held in place with a bungee cord. The black plate that you see here is a small plastic clipboard with the clip removed. It is glued in place to the light brown plate, and that is also a clipboard with the clip removed. Both clipboards are held in place with bungee cords. This allows me to remove the control head and the paddles for security reasons.

IC 7100 and Touch Paddles

IC 7100 and Touch Paddles

Remote Switch-top, SWR/RF PWR Meter-left, Speaker-right

Remote Switch-top, SWR/RF PWR Meter-left, Speaker-right








The remote switch for moving the antenna up and down to tune in each band is show in the little cubby hole. The SWR/PWR meter is stuffed into a hole where the ‘never has been used-ashtray’ was. The speaker is mounted just above the cup holder.


Remote Switch Moves Antenna Up and Down to Tune Each Band

Remote Switch Moves Antenna Up and Down to Tune Each Band

This photo shows the remote switch. It is hand held, and easily put away after the antenna is tuned.

So! That is pretty much the end of a walk through in my new mobile ham radio shack. So far, I’ve listened to CW on the road but have not called CQ or talked to anyone while driving. I became interested in CW Mobile early in my ham radio career.

The first requirement for operating CW Mobile, according to an article that I read on the subject, said to ‘become a dynamite CW operator! Its been almost 25 years since then and I’m still working on that first requirement.

I’ll keep trying!


Ernest Gregoire


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