Friday, March 13, 2020

Mobile HF/VHF/UHF Install


Icom IC-7100 install I did in my 2013 Chevy Impala LTZ covering 2m/70cm, and HF.





My main sources of information were:
  • K0BG.COM - dedicated to mobile amateur radio operators, ABCs is a good starting page.
  • Mobile Radio Systems (QRZ forums) is a good place to search for info, and post questions.


Choosing a Radio


K0BG has a good page called Miniature Radios which covers all the usual suspects.

The Icom IC-7100 is my choice for mobile, covers 160m thru 2m, and 70cm, all modes. DSTAR is an added bonus.

It's well worth spending a few bucks on rtSystems programming software, you can buy it and download it directly from them and use the supplied Icom USB cable.

QST July 2014 review of the IC-7100 available at

KV5R wrote a review covering both the good points and annoyances at
https://kv5r.com/ham-radio/2018-projects/icom-ic-7100/

Several more Icom IC-7100 reviews can be found online.

Daughter investigating the IC-7100


Radio Mounting


Radio mounted under the center console where it meets the dash, my 2013 Chevy Impala has an ideal space for a radio of this size to fit in there and easy access for the cabling. I also got the optional mounting bracket to maintain an airspace around the radio.

Control head mounting took some research, in the end I settled on a Ram Mounts RAM-B-102-UN10U. The "large phone/phablet" grip will hold the oddly shaped IC-7100 control head, makes it easy to remove and reposition.


 


Power Cabling


K0BG covers the important details in Wiring & Grounding.

I used the following items from Powerwerx:

Finding a way through the firewall in a 2013 Chevy Impala, the 2000-2005, and 2005-2013 W body Impalas use the same chassis, they have a rectangle rubber plug that can be pulled out in the passenger footwell just under the top of the carpet.

I poked a hole in the top right corner through the rubber boot with a screwdriver, then taped the power cable and coax to a piece of wire and fed it through.

Where it exits in the engine bay is close to the power steering pump pulley, I was able to cable tie the power cable and coax to the factory loom, there is enough space to freely run it between the factory loom and the firewall following the loom up with out coming into contact with anything.

Once I had the cables through, I cut a notch out of the rubber plug to allow room for the new cables and reinstalled it, I later realized I should have put a blob of RTV silicone around where the cables pass through the boot to seal it.. I might apply some coax seal when I get the chance to jack the car up again.

Pictures, note the pics of the cable passing through the firewall into the engine bay I took when pulling the cables through, as noted above they are neatly cable tied to the firewall side of the factory loom.

 


Power cabling and coax is neat and out of the way, and cable tied to the factory loom that passes through the firewall.


Antennas and Mounts


VHF/UHF:
  • Larsen NMO 2/70 antenna I've had for a few years.
  • The NMO Mount from Amazon, this one appears to good quality. I sealed where the coax is crimped with some RTV silicone and heat-shrink tube over the top.
  • I mounted this one on the front left (passenger side) fender with an NMO L bracket.
  • The coax is pre crimped into the NMO mount, I cut the coax about 1ft from the NMO mount, and pulled it through the firewall with the power cable at the same time, I then fitted an N-type female to the NMO end and N-type male connector to the other. 

HF:
  • I used this Firestick 3/8 x 24 stud and mount from Amazon. Mounted this on the rear left of the car.
    • The shape of the bracket had to be modified slightly, I had to flatten the bottom L, and adjust the angles of the other bends to get the bracket to lean outwards to clear the trunk lid gap and maintain a level mounting for the antenna. I skillfully did this with a block of wood and a sledge hammer - no joke.
    • I coated the screws with "Jet-Lube SS-30 Pure Copper Anti-Seize 12555" to prevent rust and maintain a good electrical connection. 
  • For coax I used RG-8X I had spare, this runs from the center console, under the passenger seat, under the trim to the back seat and into the trunk.
  • Single band Hamsticks - HRO sell MFJ and Shark Antenna versions of these, I got the Shark!
  • I tried and failed to get a shunt inductor to match per Antenna Coil Adjustment. So I opted for the MFJ-907 UNUN. The short coax jumper between the UNUN and antenna is RG-58.
  • Radio side of UNUN is 7 turns of coax through a pair of 3/4" mix 31 clamp on ferrites from Palomar Engineers. No common mode currents here!
  • Grounding braid to bond the hood and trunk lid, HRO sell ABR industries 233/2-G4-10 - 10ft 1/2 inch braid with nickel grommets. 
  • K0BG covers bonding and grounding in detail.
  • I'd like a screwdriver antenna, my choice would be the Little Tarheel HP.


SWR 20m:

   

SWR 40m:

  


3/8 x 24 Mounting bracket on trunk / left rear:

     

Used a spare plastic cap off a some connectors/adapters I had got at some point and kept, this keeps the water out of the 3/8 x 24 stud when the HF antenna is not on the car.

The ring terminals I waterproofed with coax seal, and three different sizes of heat shrink tube overlapping and RTV silicone between the second two pieces to ensure water tight sealing.

I plan to replace the screws with bolts and locknuts when I get the chance to get some.

That "reshaping" of the bracket could be much better, but all I had on hand was a sledge hammer, some wood, G clamps, and some ingenuity.. 

APRS over HF Mobile? You bet! See HF APRS With JS8Call.

The Final Product





Disclaimer: None of this is an endorsement of specific items, suppliers or manufactures, it's what I decided to use based on available information, personal preference, and/or what I already had.

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