Hi All,
I have a NMO antenna mounted outside my vehicle on a bracket where the bottom (coax) side of the connector is outside the vehicle. I'm worried the coax isn't weatherproofed on that side of the connector as when it is installed in a vehicle lid that section would be inside the vehicle. Does anyone have experience with the best way to address this?
Long term, you have several issues that are going to cause headaches.
The underside of those style NMO mounts are not designed to be weatherproof. They are designed to be mounted through the roof of the vehicle where the coaxial connection is protected from the elements, warm and dry. Water, road salts, etc. is going to get in there and corrode things. Water + copper + salts = a hot mess of nastyness. You could try sealing it, but from the looks of things, it's already too late.
Solution:
Drill the freakin hole and mount it like it's supposed to be. The hammy bracket mounts are a short term solution.
Or, if you really cannot bring yourself to do a proper installation, at least use the Larsen NMOHF style mounts. They used an enclosed connection on the underside that should work a bit better. It's a really good idea to to add some marine grade heat shrink tubing to the point where the coax enters the mount to seal it up. These are not really designed to be externally mounted, but if you maintain it, it'll work a bit better.
As for coax routing, yeah, it's going to get pinched and that's going to create some more issues:
-smashing the coax like that will change it's characteristic impedance. Probably not going to make a big problem, but it ain't right.
-Damage to the outer jacket will let water in. Water + copper = green corroded mess.
-Damage to weather stripping can let water into the car.
Get rid of that mess and drill a hole dead center in the roof and do a proper installation. Then you don't have to worry about any of this stuff.