Safe routing of coax with Mag Mount Antenna

[TrikeRadio]

I have a mag mount antenna that I have used on my car roof successfully. I have routed it into my sun roof which works fine except for the wind noise I have to deal with with the roof glass tilted up just a bit to not pinch the cable. I have thought about routing it through a door but I am paranoid of pinching / damaging the coax.

Is there a preferred or recommended way to route a mobile coax cable through a door without crushing it? Any methods you have used or tried that worked (or didn't work) that I should be aware of?

[OffRoaderX]

Have you tried it to see how much pinch you get?  in all of my cars there is enough rubber wind-seal around the door that it it prevents any crushing or pinching of the coax at all... at least none that is noticeable or visible.. I guess if after some amount of time it becomes a problem, i can always invest another $29 in a new cable, but so far, i have seen no crushing/pinching/damage at all.

And, although I am sure that "some people" will chime in with their theoretical thesis on how any distortion of the coax can distort the bitublar encapsulation of the protons flowing through the cable resulting in maloptimal signal conflatulation, i just remind them that I'm not bouncing my signal off the moon - i just want to talk with my friend in his car, 300 yards behind me, or hit the local repeater on the hill right above me. and then i laugh at them because i know they've never touched a boobie.

[TrikeRadio]

 I did try putting it through my door jam once... but I guess I was a bit paranoid about doing it. It did seem to make the cable take on a "bend" or some amount but straightened back out again. I was just wondering if it is better to try to lay it down lengthwise in the door jam, or toward on edge of the door or the other. And yeah... not that much to have to replace it but I don't want to damage it just because I was not doing it the best way.

[OffRoaderX]

i string it through the top of the window section. In the lower door section it might pinch.

[AdmiralCochrane]

6 hours ago, TrikeRadio said:

 I did try putting it through my door jam once... but I guess I was a bit paranoid about doing it. It did seem to make the cable take on a "bend" or some amount but straightened back out again. I was just wondering if it is better to try to lay it down lengthwise in the door jam, or toward on edge of the door or the other. And yeah... not that much to have to replace it but I don't want to damage it just because I was not doing it the best way.

Completely depends on the door and shape of the opening.  My current work vehicle lets me get the coax out a corner where there is less pinch than along the run.  In my experience with damaging coax routed thru doors, the outer plastic insulation and braids of the outer conductor usually get ugly before there is any performance decay

 

[WRYZ926]

I agree that it depends on the door and shape of the opening. I had no issues run-in the coax through the top of the door opening on my 2016 Jeep Cherokee. I had to run the coax down and around the rear hatch on my 2023 Ford Escape.

@TrikeRadio see what works best for you and your vehicle.  And you would have to really smash the coax dielectric before you would notice any effects. 

[Over2U]

If you can also form the coax into what is called a “condensation loop” (such that it enters the door jam in an upwards direction) it will help keep rainwater out of the vehicle. 

[tcp2525]

Without knowing what vehicle you are installing this in, we can only give you a generic answer. If you MUST use the door jamb the best way to do it is to follow what others have said. Personally, I totally dislike any mag mount installation because it opens up many more issues one doesn't need to deal with.

A much easier and worry free way would be to run your coax through one of the many rubber grommets you have on the firewall or the side panel next to the passenger door and place your mag mount antenna on the corner of your hood. An even better solution would be to use a trunk lip mount in that corner. I did this on my Lincoln that has a glass roof and it works perfectly without any degradation in performance. Do it once and forget about it.

 

https://www.dxengineering.com/parts/cma-cp-5nmo

[SteveShannon]

1 hour ago, WRYZ926 said:

And you would have to really smash the coax dielectric before you would notice any effects. 

I believe this is why companies use RG-58 for their mobile mounts.  It has a solid dielectric that isn’t easily smashed.  Cables that are designed to have less loss at uhf frequencies have lightweight foam dielectric material that would allow the shelf to short against the center conductor if smashed or even bent at too small a radius. 

[Socalgmrs]

1 hour ago, tcp2525 said:

Without knowing what vehicle you are installing this in, we can only give you a generic answer. If you MUST use the door jamb the best way to do it is to follow what others have said. Personally, I totally dislike any mag mount installation because it opens up many more issues one doesn't need to deal with.

A much easier and worry free way would be to run your coax through one of the many rubber grommets you have on the firewall or the side panel next to the passenger door and place your mag mount antenna on the corner of your hood. An even better solution would be to use a trunk lip mount in that corner. I did this on my Lincoln that has a glass roof and it works perfectly without any degradation in performance. Do it once and forget about it.

 

https://www.dxengineering.com/parts/cma-cp-5nmo

None of that will work very well if you have a ground plane antenna like most mag mount antennas. Mounting on the hood will make your rearward tx and rx suffer greatly.  

[tcp2525]

16 minutes ago, WRXP381 said:

None of that will work very well if you have a ground plane antenna like most mag mount antennas. Mounting on the hood will make your rearward tx and rx suffer greatly.  

Yep, that is one of the reasons why I recommend the trunk lip mount over the mag mount. But if you have to use one......

Funny thing, everyone seems to claim that mounting on the hood as I suggested performance will suffer. I agree that the radiation pattern will definitely be skewed, but in real world use it's not noticeable since the vehicle isn't always traveling only in one direction +/- 1°. I can't notice any difference in performance when I'm traveling the same routes on my car, truck(Drilled In NMO center roof), or motorcycle. Trust me, I'm very anal about squeezing out every fraction of a db performance out of an install, but this really isn't worth pissing over since everything is a tradeoff.

[SteveShannon]

49 minutes ago, WRXP381 said:

None of that will work very well if you have a ground plane antenna like most mag mount antennas. Mounting on the hood will make your rearward tx and rx suffer greatly.  

Not greatly, for the simple reason that GMRS range isn’t entirely dependent on signal strength.  As you have said numerous times GMRS relies on line of sight rather than output power. Mounting on the hood will definitely bias the direction of the signal, depending on which location of the hood it’s mounted.

[TrikeRadio]

Thanks for all the input and Ideas everyone. I'll take a look again and see if I can find a way that works best.

I am mounting this on the roof of a VW Passat Wagon. I like putting it through the sunroof but I think If i closed it all the way the fitting between the metal/glass parts would be too tight. The passenger door may be better. I'll look at it closer again.

[WRYZ926]

Look at running the cable in through the back hatch if the coax is long enough. I know there was plenty of room at the bottom of the rear hatch on my 2023 Ford Escape so there is no pinching of the coax.

[TrikeRadio]

19 minutes ago, WRYZ926 said:

Look at running the cable in through the back hatch if the coax is long enough.

Hmm.. that might work. I had not thought about the back hatch... that might work actually. gotta check my coax length but I think i might have enough.

[WRYZ926]

Running coax inside at the bottom of the rear hatch was the best solution for me. The door openings put too much of a bend in the coax for my liking.

[WRYZ926]

Let us know what works best for your situation. Each vehicle install will be different.

[WSEI509]

I am currently running mine through the sun roof that I have completely closed.  I tilted it open, ran the antenna, tilted it closed and haven't had any issues.  Now, I am running the super thin coax that comes with Midland radio antennas that's included with the radio, so if you're using anything thicker you may get different results.  I drive a 2003 Lexus GS300.

I am upgrading to an after market Midland mag mount and I'll post my results.  I may wind up mounting it on the trunk and across the trunk weather strip, then through one of the trunk wall grommets through which all the other trunk wires run. 

Kinda depends how much work you want to do.  If I'm feeling really OCD I may just drill a hole through my trunk lid and mount a larger antenna.  

 

[tcp2525]

11 hours ago, WSEI509 said:

I am currently running mine through the sun roof that I have completely closed.  I tilted it open, ran the antenna, tilted it closed and haven't had any issues.  Now, I am running the super thin coax that comes with Midland radio antennas that's included with the radio, so if you're using anything thicker you may get different results.  I drive a 2003 Lexus GS300.

I am upgrading to an after market Midland mag mount and I'll post my results.  I may wind up mounting it on the trunk and across the trunk weather strip, then through one of the trunk wall grommets through which all the other trunk wires run. 

Kinda depends how much work you want to do.  If I'm feeling really OCD I may just drill a hole through my trunk lid and mount a larger antenna.  

 

A public service message for people that want to run their coax through the sunroof.

Just be careful doing this as it might cause damage to the track mechanism. I don't know if this even apply to foreign made/designed vehicles, but for us owners of American made garbage such as Ford and GM, we are afflicted with a higher failure rate of the track mechanisms due to being made of of cheap plastic that deteriorates over time and fails. The repair kits are inexpensive, under $100 on eBay, but you have to drop the headliner and remove the sunroof structural assembly to install the parts. Mine failed from normal wear and tear on my F150. If you route your coax this way, just be aware of the pitfalls and don't force close your sunroof. Trust me, you don't want to waste your time doing the repair or paying someone to do it.

[Lscott]

On 9/1/2024 at 1:57 PM, WRYZ926 said:

Running coax inside at the bottom of the rear hatch was the best solution for me. The door openings put too much of a bend in the coax for my liking.

The RG-316 coax is higher loss, but you have to trade that off against the ease of installation. In a mobile setting the extra loss might not be that significant. One can do the numbers to see the trade off using different coax types and lengths.

https://forums.mygmrs.com/gallery/image/483-cx-5-antenna-system-analysisjpg/

https://forums.mygmrs.com/gallery/image/471-mobile-mount-with-antenna-rear-view/?context=new

https://forums.mygmrs.com/gallery/image/473-close-up-of-mobile-mount/

https://forums.mygmrs.com/gallery/image/474-mobile-mount-coax-routing/?context=new

https://forums.mygmrs.com/gallery/image/476-mobile-mount-drip-loop/?context=new

https://forums.mygmrs.com/gallery/image/475-mobile-mount-coax-extention-cable/?context=new

 

[WRYZ926]

Generally the higher loss coax is not a big deal in a mobile install since most setups are 16 feet or less with most magnet mounts having a 12 foot coax. And yes the smaller size makes running the coax inside easier.

Here is a good coax loss calculator: https://kv5r.com/ham-radio/coax-loss-calculator/ 

[TrikeRadio]

On 9/1/2024 at 3:53 PM, WRYZ926 said:

Let us know what works best for your situation. Each vehicle install will be different.

FYI.. Routing the coax through the rear hatch on my VW Passat wagon seems to have worked best for me. the angle, spacing, and rubber seal seemed to work much better than the doors or sunroof without bending the coax very much at all. Thanks for all the idea and input everyone.

[WRYZ926]

I'm glad to hear that you found a good way to run the coax in.