Extra Antenna Coax

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Danny37

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I'm using a magent mount nmo temporarily in the car with a gre scanner. I have about 8 extra feet of coax left. How do I go about cable management? I was going to coil it up but I've been told that it degrades the antenna somehow. Not sure if thats true. Any other options then cutting it to size?
 

RFI-EMI-GUY

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It won't degrade the signal. No need to cut it, especially with a temporary installation. Just don't coil it up so tightly you exceed the bend radius. If you use cable ties, make sure they are loose, not pinching the coax. Find a place to stow it where it is out of the way, under the dash on passengers side is a safe place.
 

K4EET

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It is probably cheap RG58 coax which has about 2 decibels (dB) of loss per 10 feet of cable at 900 MHz. If it were 3 dB of loss, that would be 50% of your received signal. For your case, the 8 feet of extra coax works out to 1.56 dB of loss at 900 MHz. Since it is a temporary installation, I would not worry about the 1.56 dB of extra loss.

For your final installation, what do you plan to do?
 

Danny37

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It won't degrade the signal. No need to cut it, especially with a temporary installation. Just don't coil it up so tightly you exceed the bend radius. If you use cable ties, make sure they are loose, not pinching the coax. Find a place to stow it where it is out of the way, under the dash on passengers side is a safe place.
Thanks man. Also, Any issues if the coax is touching other cables in the car? Trying to get it out of the way for now but its in contact with usb cables and audio cables.
 

Danny37

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It is probably cheap RG58 coax which has about 2 decibels (dB) of loss per 10 feet of cable at 900 MHz. If it were 3 dB of loss, that would be 50% of your received signal. For your case, the 8 feet of extra coax works out to 1.56 dB of loss at 900 MHz. Since it is a temporary installation, I would not worry about the 1.56 dB of extra loss.

For your final installation, what do you plan to do?
Its being used mostly in the UHF t-band so I'm assuming the loss is less.

Drill a hole in the roof and mount it correctly.
 

K4EET

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Its being used mostly in the UHF t-band so I'm assuming the loss is less.
You are correct. RG58 at UHF T-Band frequencies has a loss of about 0.125 dB/foot.

Drill a hole in the roof and mount it correctly.
Bravo for wanting to do the antenna installation correctly. When you buy the appropriate NMO mount with associated coax, steer clear of off-brand Chinese imports that will usually have very cheap coax and connector. I'm not sure what type of connector is on the GRE scanner that you have but I would try to avoid using an adapter. If you order the NMO mount from a respectable antenna shop, they will use whatever coax you specify and cut it to the length that you specify and professionally install the connector on it for you. It will be some clams more in cost but will be well worth the investment in the long run. I don't have first-hand experience with anybody in NYC but I can highly recommend The RF Connection in Gaithersburg, Maryland. Their website is:

 
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