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HF Mobile, A Different Kind of Radio Shack
9 May 2015 | by 
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!
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!’
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 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.
The Scorpion antenna movable coil still has the protective bubble wrap on it in this picture.
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
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!
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
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
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
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!
De AA1IK
Ernest Gregoire
9 Responses to “HF Mobile, A Different Kind of Radio Shack”
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Nice article and setup Ernest. I have had some sort of radio in all my cars and trucks since I graduated from high school in 1966. That was a small Ford Falcon a Heathkit Sixer and a 3 ring halo antenna.. I am now driving around with a IC-706MKIIG and a Outbacker Perth on a 2001 Ford Windstar.
I have worked a lot of DX from parks and Walmart Parking lots. When I travel I set the radio for VHF mostly. I reserve the HF for more fixed use.
I have a screwdriver antenna similar to yours and that will be on my truck/camper soon. Hope to work you one day mobile to mobile.
It should be noted your bonding strap is not only a great idea, but in most cases with these new plastic cars a must do. I like the second battery idea. Being a rag chewer, like I tend to be mobile, tends to drain the battery and makes me nervous.. Having a second battery solves that problem.
Again, thanks for sharing and nice setup. If I could afford a new radio I suppose it would be a IC-7100 since the 706 has done great and the 7000 I recently traded for a second KX3 also was a very good radio.
73 Harry K7ZOV
Excellent and very helpful article Ernest. Your timing (for me) is great – I’m just in the process of planning a similar setup with a newly acquired IC 7100. Is your pickup gasoline (we call it petrol down under in KiwiLand) or diesel powered? Any issues with RFI suppression? A very big thank you es 73. Phil ZL2OWL.
Yes, Phil, my truck runs on gasoline. RF problems can generally be eliminated by doing a good bonding job as described in this article. Please feel free to contact me via e-mail at [email protected]
A new Yahoo group dedicated to HF Mobile ops can be found at
https://groups.yahoo.com/neo/groups/HFMobileHamRadioCarTruck/info?firstRunExp=1
73
Excellent article. You might consider adding a battery isolator or combiner to allow your truck charging system to charge your “radio” battery. This is a very common practice in RVs and marine systems. This would keep your radio battery fully charged, and provide you with an alternate method of starting your vehicle if your primary battery fails.
Very good article. If you get to St. Pete again make sure you stop bye.
I don’t want to rain on your parade but in Florida doing a anything other than driving while moving (such as on your cell phone, CW, etc.) is labeled “Distracted Driving” – don’t get caught or you could lose your privilege to drive in Florida, or worse yet, if you are in an accident involving lose of life or property you could be personally on the hook for thousands of dollars
Good advice from K4CTV David L Dodge,
Yes, the ‘Distracted Driving’ statutes were put in place to address the many accidents that resulted from drivers ‘Texting’ both reading text and sending text. As usual, ham radio operators were thrown into the mix by this legislation. Punishing everyone for the actions of people who are stupid enough to actually text while driving was the result. Before cell phones were even invented, I know people who bragged about reading the news paper, or even books while driving!
This law is a broad ‘catch all’ meant to punish anyone for almost anything, drinking coffee, listening to the AM/FM car radio, talking to passengers, you name it!
This new paradigm behooves all radio ops to carefully evaluate their driving environment if they operate Mobile Radio.
A terrific site with tons of information for the mobile ham is http://www.k0bg.com. I can’t prais this site highly enough: I have benefited greatly from the work that Alan, K0BG, has done here.
Once, several years ago , I was stopped by the Fl state patrol and given a written warning notice for eating while driving on I- 10 @ 70 mph outside of Pensacola Fl . I was heading back home to Louisiana in my personal car when the cop past me and saw me eating a breakfast sausage sandwich with one hand.
He made a huge deal about it and told me that me if was driving a commercial vehicle he would have had to given me a ticket that would cost $300 and a ding against my CDL license. I had a CDL but had not driven trucks for over 10 year but since I was in a private personal vehicle he could only issue me an official written warning citation.
What a jerk ! Over the last 10-15 years my opinion of all cops has drastically changed and it’s mostly negative.
Just watch the cop/citizen interaction YouTube videos that are being posted everyday and watch what idiots so many of thes power hungry goofballs have become. Many are far worse the Deputy Barney Fife, many are outright criminal in their continued violations against our, WeThe People, Constitutional Bill of Rights, those offenders should be fired & jail for their many civil rights violations against law abiding folks. There is reason for the mistakes and out right lying they commit after pulling people over. Ignorance of the law and of constitutional right of those they pull over is no excuse. Careful dealing with these dangerous LEO’s & don’t trust them either. Ok rant over.