do NMO antennas have a spring in the base?

[mr_fx]

do they have a spring in the base to make the connection to the whip, or does the rubber seal provide enough pressure to do this?

 

[W5LZ]

There are several methods of doing that, a spring, in various forms, is one way. I don't think I've seen that tension applied using the rubber seal around the mount but I guess it certainly could work that way. One of the NMO mounts that I took apart had a 'V' or 'U' shaped spring 'above' the center pin. Don't loose the @#$ thing! Another had the spring in the mount it's self.
- 'Doc