GMRS Antenna Cable Run

[nU7OuxIx]

I installed a GMRS last weekend and put the GMRS unit in the glove box. I ran the cable across the cabin to the drivers side, through the little grommet, under the hood and to the passenger side where the antenna sits on the cowl. It turned out OK, but when I close the hood, it's a bit tight on the cable. I can still wiggle it with my fingers when closed, but wonder if this is going to be an issue later on.

What are your thoughts? Should I be looking at running it differently? The cable is run between the rubber hood seal and the cowl in that little tray.

Thanks!

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[chevymitchell]

I installed a GMRS last weekend and put the GMRS unit in the glove box. I ran the cable across the cabin to the drivers side, through the little grommet, under the hood and to the passenger side where the antenna sits on the cowl. It turned out OK, but when I close the hood, it's a bit tight on the cable. I can still wiggle it with my fingers when closed, but wonder if this is going to be an issue later on.

What are your thoughts? Should I be looking at running it differently? The cable is run between the rubber hood seal and the cowl in that little tray.

Thanks!

It might be alright. Can you provide some pictures of what you're looking at?

 

[nU7OuxIx]

It might be alright. Can you provide some pictures of what you're looking at?

Attached are some pictures. When closed looking down on it, it looks pretty tight. But with the hood closed, I can still push and pull the wire pretty easily without scraping insulation off.

 

[JKWMD]

I'm no expert, but I doubt that pinch would cause any problem.

 

[chevymitchell]

Attached are some pictures. When closed looking down on it, it looks pretty tight. But with the hood closed, I can still push and pull the wire pretty easily without scraping insulation off.

That RG cable is layered with the outer coating, a braid, dielectric, and then the center conductor.

The risk of it being pinched in there is egging the dielectric and then it cracking over time. However, this looks like it'll be fine for a long time like it is. Just check on it from time to time.

If it's a real concern, you can always use a file and give it some relief right there where it's at and then use some touch-up paint and it'll be perfectly fine.

I'd roll with it.

 

[nU7OuxIx]

That RG cable is layered with the outer coating, a braid, dielectric, and then the center conductor.

The risk of it being pinched in there is egging the dielectric and then it cracking over time. However, this looks like it'll be fine for a long time like it is. Just check on it from time to time.

If it's a real concern, you can always use a file and give it some relief right there where it's at and then use some touch-up paint and it'll be perfectly fine.

I'd roll with it.

Awesome, thank you!! I'll keep an eye on it in the mean time!

 

[donmontalvo]

I'm rewiring my GMRS today. I currently have my radio mounted on the passenger side of my center console. The RG-8x cable runs through my Goose Gear full platform, to my tailgate. The half-wave antenna is mounted to my Smittybilt HD Tire Carrier, which provides an atenna mount on both sides of the tailgate.

I'm leaving the RG-8x in place, since I plan to stack a small CB onto the GMRS. Then I'm running a shorter RG-8x cable to the driver's side cowl, and mounting the half-wave antenna there.

Once I reroute the GMRS antenna, I'll move the existing RG-8x cable to the CB. I already have a mount for my Wilson Flex antenna on the tailgate.

This thread has me worried about the thicker RG-8x cable getting through to the driver's side cowl, but as mentioned, if I need to, I'll cut/file away the cowl where necessary to avoid damage over time.

Here's what I have now, will post "after" pics when I'm done.

 

[smokeythecat]

I would just use it until you have a problem, then replace the cable with RG316, which is what comes with most of the Diamond or Comet antenna mounts for 2m/70cm. More attenuation, but for such a short run it isn't going to be bad.

 

[donmontalvo]

Interesting, thanks for sharing, always stuff to learn!

Didn't know there were options beyond RG-59 and RG-8x.

Agreed, I'll go ahead with the RG-8x for now, even if I have to trim the cowl to prevent pinching. Will see how that goes.

I'm trying to run the cables in a way that minimizes interference, which is why I hate to run CB/GMRS cables under the dash.

 

[donmontalvo]

Ok so looks like the cable doesn’t get crimped so shouldn’t have to change.

I installed the driver’s side cowl mount and tested the Half Wave and the Stealth/Ghost antennas.

I used a Surecom SW-102 SWR meter. How do these measurements look?

Half Wave antenna
Ch: Freq Watts SWR
1: 462.565 6.45w 1.09
7: 462.715 6.58w 1.09
15: 462.552 57.27w 1.59
22: 462.727 56.65w 1.59

Stealth/Ghost antenna
Ch: Freq Watts SWR
1: 462.565 4.30w 1.04
7: 462.715 4.31w 1.04
15: 462.552 45.27w 1.76
22: 462.727 46.25w 1.75

Does it look like I’ll need to do any trimming on the Half Wave? Or are these numbers ok?

 

[smokeythecat]

I used a Surecom SW-102 SWR meter. How do these measurements look?

There are two reasons to be concerned about SWR. One is efficiency. An SWR of 1.6:1 is still nearly 95% efficient. The other reason is to protect the final stage amplifier in your radio. I'm not really a UHF guy, which is what GMRS is, but I have always gone with the rule of 1.5:1 or less being perfectly fine. And that is with radios that have little internal protection against high SWR. You look good to go. I'd start being more concerned with an SWR higher than 2.0:1.

But if there are any real RF engineers here I'd love to hear their takes.

 

[nU7OuxIx]

Interesting, thanks for sharing, always stuff to learn!

Didn't know there were options beyond RG-59 and RG-8x.

Agreed, I'll go ahead with the RG-8x for now, even if I have to trim the cowl to prevent pinching. Will see how that goes.

I'm trying to run the cables in a way that minimizes interference, which is why I hate to run CB/GMRS cables under the dash.

Before you do any trimming or filing, I think I fixed mine the other day. I ended up loosening all the bolts on the cowl and pushed it back as much as I could while tightening the bolts. It gave me enough room so that the wire can easily move now and I'm no longer concerned about it pinching.

Just something to think about before doing something more complicated.

 

[donmontalvo]

I got lucky, the RG-8x cable didn't get pinched at the cowl. I haven't zip tied it into place yet, not sure yet what route to take under the dasy. The RG-8x is shielded better than RG-59 but I still want to find the ideal route that keeps it reasonably away from stuff that might still interfere.

 

[donmontalvo]

I forgot I also have a Wouxun ANO-050G Mobile GMRS Antenna. So I mounted it and ended up trimming 1/8” twice from the base.

A quick test with a buddy, this one seems like the best one. Here are the numbers I get:

Wouxun ANO-050G
Ch: Freq Watts SWR
1: 462.565 5.06 1.00
7: 462.715 5.01w 1.00
15: 462.552 42.53 1.29
22: 462.727 41.17w 1.30

Going on a weekend group trip to Mt Washington and Jericho Mt, will shout back with results when I return.

 

[David P.]

So a new midland MXT575 has a whopping 50 watts - does that mean there’s simply more transmitting power?

Or does that also mean more watts will run theu connections, so the antenna will need to be further away from passengers to be safer?

Is there a higher risk of electrical fire?

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