NMO Mount

[KB3NNO]

I have an NMO mount that requires a 3/8" hole for mounting. My question is that there is an insulating washer between the mount and the piece that screws onto the mount. Does this insulating washer go on the outside or the inside of the vehicle?

 

[rcvmo]

If you're talking about the rubber ring, that fits into the groove on the bottom of the brass ( or silver) nut. Best pratices are to put a small amount of the teflon grease (if supplied) or vaseline on the rubber seal before you insert into the groove. This will prolong the life of the seal.
Now for your installation. feed the cabel in from the outside of the vehicle. The wings are 3/4 " apart and will fit into the hole. Screw on the brass nut just tight enough and make sure ther's no slop (wings are into the hole.) Tighten it up. Don't over tighten or you can kiss the mount and the installation good bye. ( which will also warrant a trip to the body shop)
Good luck.
rcvmo

 

[rcvmo]

sorry about that, i'm way ahead of myself today. 3/8", has to be fed from under the roof. Then it's not a true NMO. The plastic insulator may be inserted on the top under the nut. If this is the very thin plastic white insulator, you can put that on after you tighten the nut. This isulator keeps the outside of the antenna base from scarring the metal around the circumference of the nut.
rcvmo

 

[SCPD]

The lower half of the mount, the part where the coax is soldered to, has two sets of "teeth" that will grab the metal on the underside. Scrape loose any paint/primer/corrosion in the area where these "teeth" will grab to ensure you get a good ground. The top half of the mount, or the nut portion, has a small "O" ring seal and is suppose to make the mount "waterproof" when you srew it down onto the lower half. The only insulator I'm aware of would be this "O" ring.

If you bought the NMO mount/coax cable as a package they usually have some sort of rubber gasket that fits over the nut portion and should help with making the mount waterproof when you screw the antenna onto it. Some Larsen products usually have a really nice gasket, I prefer it over the regular flat gasket that comes with some antennas.

 

[SCPD]

I agree with you there RCVMO about using vaseline on the "O" ring. I was talking about the "other" type of NMO mount, I forgot about the one you mentioned.

 

[gcgrotz]

Never ever use Vaseline, it will degrade the rubber ring. Use only teflon or silicone grease, a small tube is usually supplied with the antenna.