NMO antenna testing

CFD 4-1-8

May 26, 2010
Northern Illinois
So, its been awhile since I have had my hand on an antenna install. I installed one on my F-150 for the scanner and since the install, I have noticed that when on a mobile radio, the reception isn't up to par. (At lease not what it was like on my Expedition) Any tips on what to do to track it down? I know you can use a volt meter to check the ground, but I don't know how to do it, so I need some help. I am thinking that this is the problem.

So, any help would be great. Thanks everyone!
May 24, 2010
PG County, MD
You can use a volt meter to check and see if the braid is shorted to the center.

Remove the antenna.

One lead to the center of the connector for the radio, one lead on the outer part of the connector, it should be wide open with no resistance reading.


Lifetime VIP Donor
May 20, 2010
Check the "pin" on the underside of the NMO mount (where the coax lead attaches to the centre of the NMO antenna lead pin thing) I find those on rare occasions like to "break" their solder joint if the wire moves, someone knocks the headliner, etc.

Another thing to check is the antenna itself- if it has a "spring" at/near the base, flex the spring and make sure the center braid (antenna lead) is still attached. I go through a spring about every third year with all the salt/corrosion from winters down (or up) here- even with preventative maintenance of the spring.

CFD 4-1-8

May 26, 2010
Northern Illinois
Well, thanks for the info guys. pulled the connector off to test it with a volt meter and it was at a perfect zero. went up top, and the whip came off because the set screw is stripped. Time for a new one. thanks everyone again for your help, looks as if its time for a new one, three years with one antenna isn't too bad, especially thru the Chicago and Montana winters.

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