Installing an Icom IC 706 MKII G
in a Hummer Wagon
© Copyright 2000 - 2006 Chuck Kopelson 06/27/2000
Updated April 19, 2016
Disclaimer: Although the Icom can be modified for use on other frequencies you cannot legally transmit (in the US and Canada) on any frequencies except the amateur radio frequencies with a valid license with one exception.
In the event of a life or death emergency it is legal to use whatever means that are necessary to assist or bring help. This is the primary reason some hams have modified their radios.
Another reason to modify your radio:
The ARRL reported the following: In May, 2003, a long-awaited FCC Report and Order (R&O) in ET Docket 02-98 granted US amateurs secondary access to five discrete channels in the vicinity of 5 MHz. (60 meters) The atypical amateur allocation becomes available to US amateurs at midnight (12 AM) local time on July 3, 2003.
Information given regarding modifications is for informational purposes only.
Specifically the radio is an ICOM IC 706 MK2 G. Because the radio covers a broad frequency range you will need 2 antennas. For the lower frequencies 6 to 40 meters you will need a good quality whip and a tuner. Because this radio is capable of transmitting on many frequencies I chose to use an automatic antenna tuner. Not to get into a discussion of radio theory, it is necessary to have the antenna impedence matched to the transmitter at each frequency to efficiently transfer power to the antenna and to prevent damage to the transmitter. Typically this is accomplished by having a separate antenna for each frequency band. You would match an antenna using a SWR (standing wave ratio) meter attached to the antenna feed line at the rear of the transmitter by changing the length of the antenna or adjusting a tuning screw to achieve a low SWR. A perfectly matched antenna has a SWR of 1.0.Because it is impractical/ undesirable to mount many antennas on your truck, the antenna tuner matches the antenna to the transmitter automatically.
The SGC tuner will tune the covered bands to a SWR of 1.2 which is very good. I am using a SGC SG-237 smart tuner with an Icom AH-2b (8 foot whip) antenna mounted on the military antenna bracket. This antenna will allow the radio to operate as low as 40 meters. The nice thing about this antenna is that it can be easily stowed bent over across the rear of your truck allowing easy access to your garage. I also have adapted a military mount to the Icom whip.
For uhf 2 meters and 70cm you can get a MFJ 1729 mag mount antenna for 35 bucks or a nice Larson with a base for around 90. The 2m antenna doesn't use a tuner so I drilled a hole in the rear of the truck, inserted a bulkhead PL259 (2 male ends). I just screw the 2m antenna into the bulkhead connector and stick the antenna on the roof or the bumper. If you get the larson remember to order the magnetic mount or a bulkhead NMO mount. Since the smart tuner is in the rear corner of the truck I drilled a hole through the truck at the smart tuner output and attached a short wire directly from the tuner to the AH-2B antenna. This wire will see about 300 volts max and way less then one amp so either use the wire that comes with the tuner or any good insulated wire will do. I just laid the carpet in the back over the tuner.
The radio has a removable faceplate so you can mount the main unit elsewhere. You need to get the extension cord OPC-587 and mounting bracket MB-63 for the faceplate. I hung the transceiver (mount MB-62) under the Monsoon amp in the console. The transceiver is the size of a CB radio. I put the faceplate of the radio on a bracket located right over the tach angled to my line of sight. Since the speaker is in the transceiver you will need to use an external speaker. I plugged the speaker into the transceiver, ran the wire over the top of the overhead console and mounted the speaker to the rear of the console facing the drivers ear. This way you don't have to butcher up and cut speaker holes in the overhead console. While I had the console down and the headliner off I installed a roof mount GPS antenna and ran the wire down to the doghouse. Now all I have to do is attach any GPS unit I want to the easily accessible antenna feed.
Power is supplied to the radio by connecting an 8 ga 2 conductor wire to the plus and minus on the battery with the plus wire running through a fuse block. You can get a good fuse block at a store that sells car audio equipment. You can use any fuse between 20 to 40 amps. It's always good practice to fuse the wire near the battery. This will protect the battery and wires in case one of these gets cut and shorted to ground. In my case I installed a dual block. One for the radio and one for my lights.
I ran the power wire under the truck and brought it up into the doghouse with the heater and A/C hoses. I routed the power wires that came with the Icom from the console, down the windshield center post to the wires in the doghouse. I also put an inline fuse on the positive wire in the doghouse. The photo shows the doghouse with the cutout for the increased knee space removed.
If you need more of the clay to pack around the wires I use what electricians use to seal conduit. It's called PUG Duct Seal Model No. DS-110 made by GB Electrical. It's a 1 lb. block of soft gray clay. I picked it up at Home Depot.
The antennas and smart-tuner are mounted on the rear left so you will need 2 - 13 foot pieces of good quality 50 ohm RG-8 coax and 4 PL-259 ends. Make sure you get the correct inserts for the PL-259's to match the coax diameter you are using. You don't need 1/2" diameter direct burial solid core coax. I bought some flexible good quality coax (about 1/4" dia.) at a local marine supply store. You will also need about 20 feet of 4 conductor wire to run the power and control from the transceiver in the console to the smart tuner. I ran all the wires in the roof under the headliner.
BTW, I talked to a guy in Moscow and British Columbia from the Chicago area with this setup. Of course if you're a ham this wouldn't be a big deal.
Pickup a QST or CQ magazine and they will have all the adds for the equipment.