Antenna mount for car

[WRXR374]

I have a Hyundai Palisade, and want to have an NMO mount installed.  Wondering what brand / models to look for or avoid, or what options there might be for a semi-permanent or permanent install so I don't have to squeeze cables through windows or doors.  I know I could get a through-the metal permanent install, or a mount that attaches around the lip of the hood.  Anything else I can look at?

[kidphc]

I have a Hyundai Palisade, and want to have an NMO mount installed.  Wondering what brand / models to look for or avoid, or what options there might be for a semi-permanent or permanent install so I don't have to squeeze cables through windows or doors.  I know I could get a through-the metal permanent install, or a mount that attaches around the lip of the hood.  Anything else I can look at?

Most use larsens or motorola nmo. A lot of times they have better solder joints and materials, and cable. Not huge differences than Chinese nmos, but why bother for what $8.00 difference.

With lip mounts depending how often you open and close the opening. You still deal with the negatives of routing the cable through openings like a mag mount.

Negative to most nmos are they weren't designed to be exposed on the bottom thus possible water intrusion is a factor. They were really designed to be used in drilled through panel installations. Done properly and avoid serious whack they rarely leak.

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[WRXR374]

Thanks.

Does the cable really matter that much for this?  RG58 vs. RG8?  Obviously, a thinner cable is easier to route.  Is there enough signal loss to justify using thicker cable?

[SteveShannon]

11 minutes ago, WRXR374 said:

Thanks.

Does the cable really matter that much for this?  RG58 vs. RG8?  Obviously, a thinner cable is easier to route.  Is there enough signal loss to justify using thicker cable?

Maybe.  You do the calculation and see whether it’s worth it to you.

https://kv5r.com/ham-radio/coax-loss-calculator/

 

[WSAM454]

While the thicker cable will have a lot less loss, you are dealing with an approximate 20 foot run, and the thicker one will be very difficult to route.   Unless you are using a 5 Watt radio in the car, I would go with the RG-8 or 8x cable.

16 minutes ago, WRXR374 said:

Thanks.

Does the cable really matter that much for this?  RG58 vs. RG8?  Obviously, a thinner cable is easier to route.  Is there enough signal loss to justify using thicker cable?

As you will see from Steve's link there will be a good amount of loss with the thinner cables.  While the thicker cable will have a lot less loss, you are dealing with an approximate 20 foot run, and the thicker one will be very difficult to route, so the thinner usually wins out.   Unless you are using a 5 Watt radio in the car, with a loner than 20' run of cable, I would go with the RG-58 or 58x cable.

[kidphc]

Thanks.
Does the cable really matter that much for this?  RG58 vs. RG8?  Obviously, a thinner cable is easier to route.  Is there enough signal loss to justify using thicker cable?

I have buddies that get nuts and yes they will try to route lmr400 or 600. Worth it? I don't think so they are much thicker and stiffer. Bend radius is like 1 ft, make it tighter and you damage the insulator and will have terrible performance.

Ever notice how losses are measured in 100 ft? 4-12 ft is hardly worth it going to thicker lower loss coax, personally. On a 100-300ft run yes it's worth the cost for aircore or lmr600.

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[WRYZ926]

Most magnet mounts come with 12 or 16 foot of coax. I used the kv5r coax loss calculator that @SteveShannon linked above.

For 16 feet of coax with a 50 watt radio, SWR at 1.5 with a 3db gain antenna you will get the following results for ERP I used 467 MHz for the frequency.

RG8 - 83.7 watts

RG8X - 72.5 watts

RG-58 - 70.8 watts

Here are the same ERP numbers but with 20 feet of coax:

RG-8 - 80.1 watts

RG-8X - 67 watts

RG-58 - 64.9 watts

As you can see there is not much of a difference between the three types of coax. RG-8X and RG-58 will be smaller and easier to deal with than RG-8. With RG-8X and RG-58 and at least 3 dB of gain from your antenna, you are still getting over 50 watts ERP output with a 50 watt radio.

Of course keeping the coax as short as possible will help. But I would not worry too much about the loss of RG-8X or RG-58 in a 20 foot or less run.

[WRXP381]

Don’t worry about the small loss just get a good quality high gain antenna and the small amount of cable loss won’t matter.  And don’t get taken by the lip or fender mounts most mobile antennas need a ground plane.  A lip or fender mount will not give you that and TX and RX will suffer.  Don’t believe the guys that tell you they get a whopping 5miles with a 50w and a salt shaker lip mount.   It’s all about radiated power and not just the power in the radio.   

[SteveShannon]

8 minutes ago, WRYZ926 said:

Most magnet mounts come with 12 or 16 foot of coax. I used the kv5r coax loss calculator that @SteveShannon linked above.

For 16 feet of coax with a 50 watt radio, SWR at 1.5 with a 3db gain antenna you will get the following results for ERP I used 467 MHz for the frequency.

RG8 - 83.7 watts

RG8X - 72.5 watts

RG-58 - 70.8 watts

Here are the same ERP numbers but with 20 feet of coax:

RG-8 - 80.1 watts

RG-8X - 67 watts

RG-58 - 64.9 watts

As you can see there is not much of a difference between the three types of coax. RG-8X and RG-58 will be smaller and easier to deal with than RG-8. With RG-8X and RG-58 and at least 3 dB of gain from your antenna, you are still getting over 50 watts ERP output with a 50 watt radio.

Of course keeping the coax as short as possible will help. But I would not worry too much about the loss of RG-8X or RG-58 in a 20 foot or less run.

With those numbers I agree, go with the most durable cable that is easy to route. The difference in ERP is nearly undetectable. Plus, RG58 has a solid polyethylene dielectric rather than an easily damaged foam dielectric. 

[WSAM454]

Good info, but the recent assumptions and loss figures are for a 50 Watt radio, and the OP never mentioned how much power he will be running.   

Bottom line is to go with the RG-58U for better flexibility and easier installation.

[LeeBo]

I went with a Diamond K400S lip mount on the top of the rear door (PL259 mount) and Comet CA-2xSR antenna.  I added the Comet spring due to all the low hanging branches in my neighborhood. I routed the cable through a grommet (added silicone) and all the way to the drivers seat where I mounted the radio. Right now I have a 1.2:1 SWR reading. Not bad (if I say so myself) for my first radio/antenna combination.  I'mm hitting repeaters 30-ish miles away clearly.
 

 

[Lscott]

Nice touch with the loop around the rubber grommet. It loops over the top, around the bottom, then up a bit to feed through. The water should drip off the cable at the bottom part of the loop. These are the kind of details many people miss. That will work well to keep the water from wicking along the surface of the cable into the hole in the grommet.

[Lscott]

7 hours ago, WRYZ926 said:

Most magnet mounts come with 12 or 16 foot of coax. I used the kv5r coax loss calculator that @SteveShannon linked above.

For 16 feet of coax with a 50 watt radio, SWR at 1.5 with a 3db gain antenna you will get the following results for ERP I used 467 MHz for the frequency.

RG8 - 83.7 watts

RG8X - 72.5 watts

RG-58 - 70.8 watts

Here are the same ERP numbers but with 20 feet of coax:

RG-8 - 80.1 watts

RG-8X - 67 watts

RG-58 - 64.9 watts

As you can see there is not much of a difference between the three types of coax. RG-8X and RG-58 will be smaller and easier to deal with than RG-8. With RG-8X and RG-58 and at least 3 dB of gain from your antenna, you are still getting over 50 watts ERP output with a 50 watt radio.

Of course keeping the coax as short as possible will help. But I would not worry too much about the loss of RG-8X or RG-58 in a 20 foot or less run.

One could go through the numbers just to see the differences. I did some simple calculations for the setup on my car.

Mazda 2023 CX-5 Antenna System Analysis Rev 8.pdf

 Not the best case but I was limited in the cable size and lengths. The reduction from the best case wasn’t that severe, about a 12% calculated range loss if it was only a ERP power limitation. Likely not noticeable in practice.

[LeeBo]

8 hours ago, Lscott said:

Nice touch with the loop around the rubber grommet. It loops over the top, around the bottom, then up a bit to feed through. The water should drip off the cable at the bottom part of the loop. These are the kind of details many people miss. That will work well to keep the water from wicking along the surface of the cable into the hole in the grommet.

Thanks. I went back and added a light dab of silicone where the wire goes through the grommet, just to make sure.  I also had a friend (25-ish year HAM) helping me. 

 

[Lscott]

1 hour ago, LeeBo said:

Thanks. I went back and added a light dab of silicone where the wire goes through the grommet, just to make sure.  I also had a friend (25-ish year HAM) helping me. 

 

You both did a good job.

[tcp2525]

On 9/22/2024 at 3:45 PM, WRYZ926 said:

Most magnet mounts come with 12 or 16 foot of coax. I used the kv5r coax loss calculator that @SteveShannon linked above.

For 16 feet of coax with a 50 watt radio, SWR at 1.5 with a 3db gain antenna you will get the following results for ERP I used 467 MHz for the frequency.

RG8 - 83.7 watts

RG8X - 72.5 watts

RG-58 - 70.8 watts

Here are the same ERP numbers but with 20 feet of coax:

RG-8 - 80.1 watts

RG-8X - 67 watts

RG-58 - 64.9 watts

As you can see there is not much of a difference between the three types of coax. RG-8X and RG-58 will be smaller and easier to deal with than RG-8. With RG-8X and RG-58 and at least 3 dB of gain from your antenna, you are still getting over 50 watts ERP output with a 50 watt radio.

Of course keeping the coax as short as possible will help. But I would not worry too much about the loss of RG-8X or RG-58 in a 20 foot or less run.

Might as well use a dummy load if you're not feeding our NMO mount with RG400.

[WSAM454]

47 minutes ago, tcp2525 said:

Might as well use a dummy load if you're not feeding our NMO mount with RG400.

These "400" cables can get confusing.   The RG-400 you mentioned is a small diameter teflon Mil Spec cable with a 400MHz loss of over

8 dB/100ft.

https://www.awcwire.com/rg-catalog/rg400-coax-cable

 

You probably meant to write LMR-400, which is the agreed-upon default cable at a moderate price, for UHF operation with low loss.

[tcp2525]

18 minutes ago, WSAM454 said:

These "400" cables can get confusing.   The RG-400 you mentioned is a small diameter teflon Mil Spec cable with a 400MHz loss of over

8 dB/100ft.

https://www.awcwire.com/rg-catalog/rg400-coax-cable

 

You probably meant to write LMR-400, which is the agreed-upon default cable at a moderate price, for UHF operation with low loss.

Nope, MIL-Spec RG-400. Don't need a 100' run in a car.