1994 GMC Sierra install

[jr_racefan88]

I have a 1994 GMC Sierra standard cab and was thinking about putting a Cobra LTD 29 Classic NW in it but I am not sure where would be the best place to run the coax out and how to get power. Any ideas?

[TX_Dj]

Where are you going to place the antenna? If you're going to use a puck mount or other thru-the-roof mount, you'd need to find a way to get the coax up into the headliner. If you're going to use a mag mount on the roof, another popular option is to push it up the headliner thru the 3rd brake light, out the bottom of the 3rd brake light up to the roof.

If you're going for a mount in the bed, there are likely to be rubber "plugs" in the floorboard you can run the cable under the carpet and out thru one of these plugs.

As for power, a straight drop to the battery is probably best, and if you think you'll ever run an amp, size your power drop accordingly. I ran 8ga wire in thru some grommetted holes I drilled in the transmission hump area, those wires feed my radio gear. Fuse fuse fuse! No need to burn up a good truck because of inadequate fusing on a drop like that.

[jr_racefan88]

I think I am going to get the Wilson Little Wil antenna with the magnetic mount and put it on the bed rail and run the coax between the bed and cab. My truck has vinyl floors so that complicates running it through the bottom of the cab since I can't pull back the vinyl. I have found a punch out in the firewall and there is plenty of room there but punching that out may be easier said than done. Would there be an option to wire it through the fuse box at all or is the battery best?

[TX_Dj]

You can run it off a vacant fuse block, but there may be more noise in there than a hard line to the battery. Also, if using an existing grommet in the firewall, be careful what else is going thru there, cuz the wire can pick up noise from whatever that is as well. There may be noise anyhow, regardless of what you do, in which case you might need a noise cancelling device for the power line near the radio. Both my CB's pick up noise from the ignition, but if I click on the ANL on the radio, it clears up. Some folks aren't so lucky.

I recommended the hardline to the battery because A) I knew I was going to add an amp eventually, and B) I like to run the radio w/ everything switched off. Also, my electrical kills power to everything when I crank the engine, and running the hard line eliminates that issue.

[jr_racefan88]

Got the radio hooked up and cable ran. I found a punch-out underneath the driver's seat so I had to take the seat loose to access it. I then ran it underneath the vinyl and came back up right behind the gas peddle. I went ahead and ran the positive wire to the fuse box. I will post some pictures tomorrow.

[jr_racefan88]

I calibrated the antenna yesterday and got channels 1, 20, and 40 all around 1.5. Today I had to unhook the radio momentarily and when I hooked it back up, I checked the SWR again and this time it was giving me channel one at 1.5, 20 at about 2, and 40 just above 3. So my question is how does this happen and should I drive maybe out to the interstate and check it again to be sure?

[jr_racefan88]

I calibrated the antenna yesterday and got channels 1, 20, and 40 all around 1.5. Today I had to unhook the radio momentarily and when I hooked it back up, I checked the SWR again and this time it was giving me channel one at 1.5, 20 at about 2, and 40 just above 3. So my question is how does this happen and should I drive maybe out to the interstate and check it again to be sure?

I also forgot to add that it was raining when I checked it...not sure if that would have anything to do with it.

[TX_Dj]

Yeah, wetness and humidity alter swr readings. Being in motion or in a windy environment will alter your readings on a whip. And being in a few hundred feet proximity to power lines, trees, light poles, cars, concrete barriers or anything else can alter your readings as well.

Once you get everything going, you'll notice that 19 hushes up in a rain storm... not because people aren't trying to talk, necessarily, but because the rain diffuses and/or absorbs the RF and other things as well. Sorry, I don't have the data on why, per se, and don't have time to look it up.

[jr_racefan88]

Alright thanks. So I guess my best option is to wait and check it when its dry and out in the open and be done with it as long as it is good.