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Rubber seal on nmo mount

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#1
Hi. I had a cb and 70cm/2m installed. I switched the antennas so the cb would be behind the driver side. The seals are different. Will they still prevent rain etc. i hand tightened them only.

 

W9BU

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#3
The rubber gasket/o-ring/seal should stay with the antenna. Assuming that both antennas are designed for NMO mounts, you should be able to carefully move the seal to the other mount so it can stay with the antenna.

Yes, there are some sealing methods for NMO mount antennas that are interchangeable, but I think it's best to keep the seal with the antenna that it came with.
 
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#4
The NMO mount itself has an O ring under the outer nut. If properly installed at the shop, it'll keep the mount watertight and keep moisture out of your vehicle.

The outer seals are there to keep water out of the antenna base/NMO connection. You do want the correct seal installed. As stated above, they need to stay with the antenna.
 
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#5
The NMO mount itself has an O ring under the outer nut. If properly installed at the shop, it'll keep the mount watertight and keep moisture out of your vehicle.

The outer seals are there to keep water out of the antenna base/NMO connection. You do want the correct seal installed. As stated above, they need to stay with the antenna.


The seal on one mount the 2m is under the gold female screw thingy. I don't think it will come off unless I unscrew it. Do u know how it cones off? Or should I just switch it back?
 
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#6
The 'seal' in the first photo seems to be from older AS mount. NMO mount does not have that 'seal'
The added gasket with some NMO mount antennas is flat and fits around the mount, not under it.

Antenna 101.
 
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#7
My TRAM 2 meter/440 antenna came with two seals. One is just a simple O-ring fitting into a groove on the base of the antenna and the other is a flat seal with flanges that has a ridge fitting into the groove on the antenna base. The instructions said to use the O-ring alone if the antenna is going to be removed periodically and use the flat seal if the antenna is going to be permanently mounted. Since I take mine off the vehicle at night, I use just the O-ring. I also bought plastic caps that thread onto the NMO mount and have an O-ring seal in them. These, coupled with the O-ring in the mount itself, have prevented any leakage into the vehicle.
 
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#8
The seal on one mount the 2m is under the gold female screw thingy. I don't think it will come off unless I unscrew it. Do u know how it cones off? Or should I just switch it back?
Not sure exactly what you are referring to.

On the actual NMO mount, with the antenna removed, there is an O ring under the outer threaded part. When installed, they should be lubed up with some silicon grease. The installer should have done that. No reason to remove it, just leave it all in place. Just know it's there if you ever have to remove it for any reason, of if the mount comes loose.
That O-ring will maintain the waterproof nature of the mount and keep water out of the inside of your vehicle.


It's common (and a good idea) to have a separate sealing mechanism on the base of the antenna coil. This is to keep moisture out of the mating area between the NMO mount and the antenna coil. Moisture accumulating under there can cause corrosion.
The different types and brands of antenna coils will have different ways of doing this. Different brands and different model antennas are not necessarily compatible with the other types.

It looks to me like you have the rubber gaskets under the antennas swapped. You can just unscrew the antennas and remove the gasket and put them under the correct antennas. They should match up with the antenna base.

Hard for me to tell what you have, but one of them looks like a Larsen antenna coil/base. That looks like it should be using the larger gasket that's under the antenna coil with the silver ring.
 
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#9
The cb mount did not have an outer ring gasket. The 2m mount did. The 2m has a bigger footprint. The cb antenna is a rotel. The cb antenna fits right on the gasket that is under the nmo mount. I just switched them back.
 
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#10
Hi. I had a cb and 70cm/2m installed. I switched the antennas so the cb would be behind the driver side. The seals are different. Will they still prevent rain etc. i hand tightened them only.

Nmo mounts have an o ring that seals water out so its not needed
 
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