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Coax Cable and Connectors - For general discussion of all things pertaining to coax cable, wave guide or any other medium for passing RF energy. This includes connectors, weather proofing and grounding.

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Old 04-30-2017, 11:42 AM
   
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Default coax length

hey everyone. I've got an Uniden with a proper mag mount antenna and the coax is only about 10 to 12 feet which is not long enough for me. If I was to get about 25' foot extension would my scanner still work right? Or would that throw everything off? I can only seem to find 25 foot cords and I'd have to use a BnC connector joiner, but I'm worried it won't work properly. Or should I buy a new antenna with a longer cord? Looking for advice. I listen to OPP EMS and FD and MTO if that helps with freq range.

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Old 04-30-2017, 12:34 PM
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You don't want a lot of extra coax that you don't need because of loss. So its best to get a cable made to the length you need. There are plenty of places that make custom length cables. Or you can get the connector and crimper and make it yourself.
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Old 04-30-2017, 4:58 PM
   
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Quote:
Originally Posted by gonefishn1 View Post
You don't want a lot of extra coax that you don't need because of loss. So its best to get a cable made to the length you need. There are plenty of places that make custom length cables. Or you can get the connector and crimper and make it yourself.
ok guess ill maybe talk to the place i bought this antenna in toronto and maybe see if i can get one made with about 20' its just too short. i almost think its only 10'

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Old 04-30-2017, 5:10 PM
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You can measure the length you need with a rope or string so you will be more accurate in length.
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Old 04-30-2017, 5:29 PM
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A mere 25 feet of coax isn't going to kill your VHF Fleetnet signals. It'll be fine.
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Old 05-01-2017, 1:18 AM
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I agree, it's not going to hurt anything.

Yes, it'll add some more coaxial cable losses, but that'll happen if you build a custom mount with extra cable. There is going to be a tiny bit of additional loss from the extra connectors, but unless you have high end test equipment, you'll never know it's there.

Just add what you need. Next time you replace the mag mount, get one with longer cable.
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Old 05-01-2017, 6:12 AM
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A good reference for loss.. Coax Attenuation Chart

A good RG-58 at 100 foot long shows 4.8db loss.. so your 25 foot addition would add 1.2db of signal loss.. and at VHF I doubt you'd notice it at all unless you were on the fringe of the system
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Old 05-02-2017, 2:32 PM
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Just buy a good quality coax, and wrap the joint (connection) with something like Coaxseal or self-fusing butyl tape (or silicone) to ensure it is watertight, if it is going to be outside the vehicle.
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Old 05-02-2017, 8:46 PM
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This is the stuff. Stretch it until it screams.

https://www.princessauto.com/en/deta...pe/A-p0700353e
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Old 05-02-2017, 9:10 PM
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Default coax length

Please, no butyl. If you ever need to get at that connection in the future, you'll regret using butyl.

Instead, use the tape SlicerWizard recommended. If your near a Home Depot, this stuff is very similar: https://www.homedepot.ca/en/home/p.s...000101995.html
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Old 05-03-2017, 8:52 AM
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Quote:
Originally Posted by MikeOxlong View Post
Please, no butyl. If you ever need to get at that connection in the future, you'll regret using butyl.

Instead, use the tape SlicerWizard recommended. If your near a Home Depot, this stuff is very similar: https://www.homedepot.ca/en/home/p.s...000101995.html
Oh yeah, butyl can be a nightmare. However, before using it, wrap the connector with a thin layer of teflon tape. Then overlay with butyl tape. The butyl still needs to be in direct contact with cox at each end of the wrap to maintain a weathertight seal. When the time comes that you need to remove the butyl, you don't have near the amount of frustration.
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Old 05-03-2017, 12:35 PM
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Default coax length

Even using a "courtesy wrap" of electrical tape is frowned upon although it's better than straight butyl.

Butyl gets everywhere and can be a real sticky mess. Our rigging crews will let you know exactly how they feel about it when they encounter it.

We were supplied butyl for temporary repairs and the riggers confiscated it as soon as they saw it. They were quite happy to hand out rolls of Scotch 130C tape to replace it.
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Last edited by MikeOxlong; 05-03-2017 at 8:34 PM..
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