RadioShack Pro-18 Mobile Antenna

Seanm214

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Hello everyone,
I recently purchased the Laird 7603 phantom antenna with NMO 3.5 inch round magnetic mount 12 foot CX BNC connector for the antenna. I heard great things about this tiny whipless antenna and I am going to use it with my RadioShack pro-18 in my car. This is my first mobile antenna and I wanted to come on here to ask what is the best way to get the coaxial cable from the mag mount into the car. I want to run it through the passenger side door but don’t want the door to crush the coax and I’m wondering what the proper procedure is for this as I am new to all this.
 

krokus

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If you are putting the antenna on the roof, running the cable down the outside of the weather gasket, then in through the bottom of the door, gives water a path away from the interior. There will be some compression of the cable, which using a gap in the gasket can minimize.

There will be some chatter from the cable catching the wind, along the roof. This can lead to paint discoloration, or damage.

If this is going to be a permanent installation, the mount itself will lead to paint damage and discoloration. (There are multiple threads on this site about this topic. Drilling the roof for an quality NMO mount is a much better answer.)
 

Seanm214

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If you are putting the antenna on the roof, running the cable down the outside of the weather gasket, then in through the bottom of the door, gives water a path away from the interior. There will be some compression of the cable, which using a gap in the gasket can minimize.

There will be some chatter from the cable catching the wind, along the roof. This can lead to paint discoloration, or damage.

If this is going to be a permanent installation, the mount itself will lead to paint damage and discoloration. (There are multiple threads on this site about this topic. Drilling the roof for an quality NMO mount is a much better answer.)
Can you post a link to one of the threads explaining it?
 

iMONITOR

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Is

Is it really that bad to mount it on the roof?
It's not bad from a performance perspective. But if you don't know what you're doing you might want to get someone experienced to help or do it for you. You don't want to end up with a leaky rusty hole in the roof of your Jaguar. There's also a chance you could run damage some internal wiring harness in the car when drilling holes ETC.
 

Seanm214

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Kings Park, NY
It's not bad from a performance perspective. But if you don't know what you're doing you might want to get someone experienced to help or do it for you. You don't want to end up with a leaky rusty hole in the roof of your Jaguar. There's also a chance you could run damage some internal wiring harness in the car when drilling holes ETC.
Don’t want to risk it with my jaguar. I’ll try the roof of my Ford Fusion 2011.
 
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Seanm214

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Kings Park, NY
It's not bad from a performance perspective. But if you don't know what you're doing you might want to get someone experienced to help or do it for you. You don't want to end up with a leaky rusty hole in the roof of your Jaguar. There's also a chance you could run damage some internal wiring harness in the car when drilling holes ETC.
I know this is probably a stupid question but are mag mount antenna ok on top of the car when it rains out, like the rain won’t damage the antenna and the mag mount right?
 

iMONITOR

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I know this is probably a stupid question but are mag mount antenna ok on top of the car when it rains out, like the rain won’t damage the antenna and the mag mount right?
Not a stupid question. However it's not a good idea. They trap moisture, grit and salt underneath. It will dull and scratch maybe even change the color in the paint in a short time. If you keep it clean and polished the mount will probably slide off. At high speeds they can loose their hold and fly off, denting and scratching your vehicle. They usally don't have a good ground, depending on how you install your scanner.

What frequencies/bands do you monitor? Is your area a weak or strong signal area? Everyone's situation is different. I get buy with a hand-held scanner in a cup holder with a rubber ducky antenna.
 

Seanm214

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Location
Kings Park, NY
Not a stupid question. However it's not a good idea. They trap moisture, grit and salt underneath. It will dull and scratch maybe even change the color in the paint in a short time. If you keep it clean and polished the mount will probably slide off. At high speeds they can loose their hold and fly off, denting and scratching your vehicle. They usally don't have a good ground, depending on how you install your scanner.

What frequencies/bands do you monitor? Is your area a weak or strong signal area? Everyone's situation is different. I get buy with a hand-held scanner in a cup holder with a rubber ducky antenna.
Yea I’m monitoring local 800mhz trunked police with my handheld scanner. My 800 MHz antenna works alright outside of the vehicle but when I put it in the cup holder with just the rubber duck antenna it’s hard to get signal most of the time which is why I need the mobile mag mount. I’m just worried about when it rains if water will run into the vehicle from the coax. Idk if that will definitely happen or maybe it won’t happen at all. Maybe when it rains I’ll just take off the mag mount. Drilling a hole is not an option right now unfortunately lol.
 

DJ11DLN

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krokus

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Yea I’m monitoring local 800mhz trunked police with my handheld scanner. My 800 MHz antenna works alright outside of the vehicle but when I put it in the cup holder with just the rubber duck antenna it’s hard to get signal most of the time which is why I need the mobile mag mount. I’m just worried about when it rains if water will run into the vehicle from the coax. Idk if that will definitely happen or maybe it won’t happen at all. Maybe when it rains I’ll just take off the mag mount. Drilling a hole is not an option right now unfortunately lol.
How about an on-glass antenna for that? No permanent damage, is low profile, and easy to install. Not optimal, but better than the rubber duck.

 

krokus

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Can you post a link to one of the threads explaining it?
Here are a few...




 

mmckenna

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Yea I’m monitoring local 800mhz trunked police with my handheld scanner. My 800 MHz antenna works alright outside of the vehicle but when I put it in the cup holder with just the rubber duck antenna it’s hard to get signal most of the time which is why I need the mobile mag mount. I’m just worried about when it rains if water will run into the vehicle from the coax. Idk if that will definitely happen or maybe it won’t happen at all. Maybe when it rains I’ll just take off the mag mount. Drilling a hole is not an option right now unfortunately lol.

Yeah, your car acts like a big RF shield. If you have tinted glass, some of it uses a metal film that can effectively block RF. Add in electric window defoggers, and it'll do exactly like what you are seeing.

Drilling the hole really is the way to go, but I know that's a hard decision to make. It's worth it, but I understand.

Getting the coax inside the vehicle is the challenge. Not only do you have to worry about water ingress, but you really do need to consider damage to the coaxial cable. There are two main ways that the cable can get damaged:
1. Pinching. When the cable gets pinched it changes the impedance of the cable. Not so much an issue for scanners, but an issue for transceivers. Pinch it enough and the center conductor can migrate inside the dielectric and touch the outer shield, shorting it and effectively killing any reception.
2. Abrasion/jacket damage. That'll let water into the cable. The water and the copper will mix and make an awful mess and destroy the cable from the inside out.

Since leaving a window cracked open is not going to be a reliable option, finding another path that doesn't involve pinching the cable in the door would be a good idea. Trunk lids are not much better and the same with the hood. Sometimes coming down under the vehicle and back in can help, but then you have a cable running down the side of your car.
Kind of a catch-22.
If looks are more important than performance, a glass mount cellular style antenna would be an OK option. Not great, but OK.
Trunk lip mounts have the same issue with cable pinching/damage. That and letting water into your trunk isn't a good idea.

Let us know when you are ready to drill.
 

Seanm214

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Messages
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Location
Kings Park, NY
Yeah, your car acts like a big RF shield. If you have tinted glass, some of it uses a metal film that can effectively block RF. Add in electric window defoggers, and it'll do exactly like what you are seeing.

Drilling the hole really is the way to go, but I know that's a hard decision to make. It's worth it, but I understand.

Getting the coax inside the vehicle is the challenge. Not only do you have to worry about water ingress, but you really do need to consider damage to the coaxial cable. There are two main ways that the cable can get damaged:
1. Pinching. When the cable gets pinched it changes the impedance of the cable. Not so much an issue for scanners, but an issue for transceivers. Pinch it enough and the center conductor can migrate inside the dielectric and touch the outer shield, shorting it and effectively killing any reception.
2. Abrasion/jacket damage. That'll let water into the cable. The water and the copper will mix and make an awful mess and destroy the cable from the inside out.

Since leaving a window cracked open is not going to be a reliable option, finding another path that doesn't involve pinching the cable in the door would be a good idea. Trunk lids are not much better and the same with the hood. Sometimes coming down under the vehicle and back in can help, but then you have a cable running down the side of your car.
Kind of a catch-22.
If looks are more important than performance, a glass mount cellular style antenna would be an OK option. Not great, but OK.
Trunk lip mounts have the same issue with cable pinching/damage. That and letting water into your trunk isn't a good idea.

Let us know when you are ready to drill.
I put the mag mount on top of the car and ran it through the door. Doesn’t look like the coax is getting pinched. The weird thing is in some areas the antenna just won’t work. For example I just went to the grocery store with the antenna and I had no trunking signal with the antenna in the parking lot. I unscrewed the mag mount coax bnc from my scanner and put in the rubber duck and I was getting reception!! How is it that I was getting signal with my rubber duck and not my mag mount antenna!!?? What’s wrong here?
 
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