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Author Topic: DC Power and Ford Explorer  (Read 350 times)
W9PMZ
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« on: June 25, 2005, 05:49:19 AM »

I have a 2003 Ford Explorer and want to install an ICOM 706MKIIG.  Before I get out the drill, does anyone have any good tips on how to run the DC through the firewall?

Thanks,

Carl - W9PMZ
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AA4PB
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« Reply #1 on: June 25, 2005, 08:23:33 AM »

Look for a grommet where the parking brake cable or the accelerator cable goes thru the firewall. You can often open the hole enough to add the power wires. Stay away from the vehicle wiring harness because its too easy to damage that harness.
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N6AJR
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« Reply #2 on: June 25, 2005, 10:30:30 AM »

I drill 2 holes up above the carpet on the passenger side foot well. I bolt the neg to the floorboard and attach all the neg leads to the bolt sticcking through the floor insude. good ground, cuts down the noise.  

I run a pos from battery ( with fuse) through #2 hole ( with grommet) and attach all pos leads here  wrap with tape put in tupperware box ( no shorts ) and cram it under dash.  I use black and red 5 foot starter cables from the auto store, flat end with hole in it, about $5 each, and carry 300 amps or so.  works
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K1CJS
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« Reply #3 on: June 25, 2005, 06:32:27 PM »

Agreed on staying away from wiring harnesses--unless you want a noise problem.  

There is usually a grommet for the standard vehicle antenna (if it is mounted on the front fender, that is) that you may be able to get your wiring through.

Look on both sides of the firewall if you can, and slowly and carefully work an awl through the grommet, away from the antenna cable.  Carefull enlarge that hole a bit, then work your wires through it.  When you get the wires into the proper position, seal the poke-through with a bit of silicone sealer--you may not need to if you've been careful.  Remember to fuse both wires at the battery with weather resistant fuseholders, make your connections under the dash and you're done.

I've been doing simple installations like that for years with no noise and no damage, and when it comes time to remove the wires, you can pull them out and leave no trace of them being there at all.
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KC8VWM
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« Reply #4 on: June 25, 2005, 09:22:29 PM »

Tips you ask?

Ok, here's KC8VWM's top ten tips for ya...

#1 Go out and buy a "monster cable" which is normally used for car audio amp installations. These wires are normally rated in the 25 amp range. You may also choose to purchase the "optional" battery post connector that has the extra wingnut on it for a seamless radio connection to your battery.

#2 Never run the wires while the power is connected to the battery terminal. I know, this is self explanatory - but you would be surprised how many people forget about this simple but important fact.

#3 When K1CJS says, "Remember to fuse both wires at the battery"  He really means the fuse should be as close to the battery as physically possible. The positive wire should never "pass over" the negative battery post etc. (unless you like watching a rather entertaining battery meltdown) Also be sure that the fuse assembly isn't crushed when the hood is closed.

#4 Install a snap on ferrite bead / RF choke near the entry point where the wires runs into the firewall. This will help prevent any stray noise or RF from traveling along the cable.

#5 Keep power cables clear of anything that generates heat, on-board computers, vehicle sensors, alternators, digital dash wiring - odometer cables etc. If the cables are running too close to a manifold - heat will breakdown the cable and an electrical short will eventually occur.

If the cable is in proximity of a spark plug or alternator wire vehicle noise may get into the radio. If the wire passes over a harness wire under the hood, you may experience wild things happening inside your car while transmitting. For example, if you have a digital odometer/speedometer it might stop working when you TX. etc.

#6 Use "nylon" and NOT plastic tie downs to keep the wire from moving out of it's intended route to the battery. Don't skimp on quality. Cheap plastic tie downs will melt or break away very easily. Don't trim them off too short.

#7 Install a noise suppressor on the cable even if you think you may not need it. Why...?  Well you will have your answer the next time you are sitting at a traffic light parked next to a noisy car beside you.

#8 If you install an external speaker/ PA speaker in your car, ensure the speaker cables are always shielded and attach an RF choke on the wiring a few inches from the the back of the radio.

#9 Use shrink tubing over any splices or soldered connections in a mobile installation. Using electrical tape is almost useless as it will just unravel from heat and expose the connection in a matter of days.

#10 Keep all installed cables located under the dash secure. Never run a cable in a manner that it will interfere with your vehicle controls such as the gas pedal or brake pedal.

Enjoy the new radio installation!

73 Charles - KC8VWM

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WA7UNW
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« Reply #5 on: June 26, 2005, 10:09:41 AM »

Check the Mobile Ham forum here. There is a ton of info.
Also check out Alan's website: http://www.k0bg.com/
He does a lot with mobile HF and is a good resource. He also answers emails/posts quickly.

73
Mike
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W9PMZ
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« Reply #6 on: June 26, 2005, 03:38:51 PM »

One other question, much has been made on the aspect of running the cable such that the cable is not near the wiring harness.  On the Explorer the harness and battery are both on the drivers side.

If I run the cable to the passanger's side this would add a lot of wire to the DC run and have the the potential to pick up more noise.

For the optimal installation should the DC cable be on the passange side, with more cable.  Or should it be on the drivers side, for a shorter run, but nearer the harness.

Thanks to all for their comments.

73,

Carl - W9PMZ
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AA4PB
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« Reply #7 on: June 26, 2005, 06:45:00 PM »

The added distance is probably not enough to have any affect on noise pick up. Most rigs are not very sensitive to noise pick up on the power leads. The most common problem is alternator whine which is usually a matter of alternator currents flowing in the ground leads rather than coupling into the power leads from being too close to other wiring. In my experience, most ignition noise comes in via the antenna.

The issue of being near the cable harness running thru the firewall is a mechanical one. That is, damaging the harness while trying to poke holes thru the rubber boot that the harness passes thru. This is why I recommend the parking brake or accelerator cables.
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VK2TXB
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« Reply #8 on: July 28, 2005, 11:17:36 PM »

Curious,
After you put your 706 in the explorer, how was the noise levels?? I have same radio and car and my god!! continuous S8-9 noise all the time! Let me know if you had any problems after finishing project.
Cheers
Andrew
VK2TXB
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