2m Mobile INSTALLED!

[kjp1969]

Bob,
Good point, I hadn't thought of that. Nothing else on any of my cars has a negative ground on anything. Do you think that same condition would affect the ECU, AM/FM, etc?

Martin,
Here are some photos to give you an idea of what I was talking about. First is a grommet with a loom passing through it. This is just below the upper tire carrier rack, and it carries power for a work light and the coax for my 2m.

In the engine compartment, "my" loom is the shiny black with white zip ties, while Ford factory is the dull black. Across the cowl I snuck into the factory clips for the a/c pipes and used a few zip ties. Otherwise, I usually zipped my loom to the Ford loom, following their routing whenever convenient. The penetration through the firewall is using a waterproof emt elbow- I half expected it to melt from the heat; time will tell. The loom fits tightly, no chance of water entry, even though it's oriented upward.

I threw in a shot of the aux fuse block. I labeled the wires using a label maker and clear shrink, but some of the lettering has faded over time. This install has been in place for around 6 months. Not shown is a big 50 amp fuse at the battery.

 

[GlennA]

I'm at work and consequently cannot see most of the pics associated with this thread. Is there a reason he cannot connect the ground to the vehicle chassis where he already secured the radio mount? This is assuming it doesn't introduce any unwanted noise on the line.

I always try to stay away from a direct connection to the battery. Most vehicles have "power points" at the under hood fuse panel that allow secure connections without the chance of corrosion.


EDIT: Not intending to burst your bubble, but I do this type of work daily. A quality installation will save many headaches (malfunctions) in the future.

Now that i can see the pics, the first thing I would do is strip the wiring out and start over. Run the wires over the steering column behind the dash and secure with zip ties. Install the grommet and pass the wires through the firewall. Fish the wires between the the fender and the fuse panel (plus the other under hood obstacles) and zip tie in place. I would connect the ground to the point on the fender just behind the battery and the positive to the fuse panel behind the battery.

Installing the radio in-dash would be my preferred setup. YMMV.

 

[DaveInDenver]

One reason radios are installed with both power leads to the radio is for noise immunity. If the positive and negative leads are the same length and run in the same environment, then the designer can build a very effective common mode choke. If the power leads are not balanced, then you have to be very careful in the run and might have to shield the power cable. The battery itself acts like a pretty good filter and the power is generally pretty clean. If you go straight from that point with a known feed, then you can expect clean power at the radio. You can be careful not to have long runs next to the ECU or ignition. The manufacturer, who could care less about RFI since most devices like GPS will have their own SMPS, likely will bundle the outlet wiring with the rest of the vehicle harness. Our ham radios are throw-back high power linear devices.

They also do this to minimize voltage drop at high transmit. Most radios are designed to work most efficiently at ~13.5V, so with your truck running the battery will be sitting at around 14V. But if it's just on battery power, the battery might be sitting at 12.3V. So if your radio draws around 10A at TX and you're using 10' of 12AWG wire, you can expect about 0.25V of drop. But if the supply was to neck down someplace to 18AWG or 20AWG like would be fine to power a cell phone charger, that circuit will drop 1V or more. Most radios will be ~80% or less of full power at 12V, so it's entirely possible that with the truck off, the radio might see 11.5V or less even with solid power cables. At 11V most radios are going to be a lot lower than their full rated power.

BTW, Martin, A&A Trading Post down the street has boxes of grommets you can dig through to find the right size. You pick them based on 2 dimensions primarily. First is the size of the hole in the sheet metal, this is the OD of the grommet. The ID of the grommet is the outer diameter of the wire passing through. The last measurement is the thickness of the wall, which is thickness of your sheet metal. That's usually going to be 1/16".

 

[Martinjmpr]

BTW, Martin, A&A Trading Post down the street has boxes of grommets you can dig through to find the right size. You pick them based on 2 dimensions primarily. First is the size of the hole in the sheet metal, this is the OD of the grommet. The ID of the grommet is the outer diameter of the wire passing through. The last measurement is the thickness of the wall, which is thickness of your sheet metal. That's usually going to be 1/16".

Dave: Reinstall is done.

http://www.expeditionportal.com/forum/threads/70419-Ham-install-version-2-0

I think you'll agree the second time it looks much nicer. I did make a couple of stops at A&A, but I didn't realize they had grommets. I think my small grommet will work, I just need to seal it in with RTV tomorrow when it's (finally!) warm enough to do that.

BTW, are there any repeaters you normally monitor out there? I was listening to a couple on my way to work Monday but I wasn't sure whose they were and whether they were open or closed repeaters.

 

[AA1PR]

I also have to say get a grommet aroudn the wires or otherwise you may run the risk of having your battery short out when they rub through & worse

 

[Martinjmpr]

I also have to say get a grommet aroudn the wires or otherwise you may run the risk of having your battery short out when they rub through & worse

Again: http://www.expeditionportal.com/forum/threads/70419-Ham-install-version-2-0

 

[brussum]

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Kjp1969,

What make/model I'd your fuse/distro box? That's a good looking unit and I want to do something similar. Would you recommend it or buy the same unit a second time?

Thanks,
John

 

[kjp1969]

Kjp1969,

What make/model I'd your fuse/distro box? That's a good looking unit and I want to do something similar. Would you recommend it or buy the same unit a second time?

Thanks,
John

It's made by Bluesea and they have a bunch of different configurations. It's a marine item so all metal is stainless. I have no complaints with it.

 

[brussum]

Thanks! It makes for a much cleaner install than a dozen accessory wires off the battery.