Fw: [aprssig] Re: I'm gonna drill....Right tool for the job..

[tvsjr at sprynet.com]

>The NMO hard mount is designed to be installed entirely from above 
>(assuming you use a hole saw or antenna cutter instead of a two-piece 
>Greenlee chassis punch).      The mount normally inserts from above, 
>coax (without connector) first. It has tabs that hook under the sheet 
>metal and a circular flange that centers exactly in the 3/4" hole. . The 
>assembly is drawn up tight against the underside of the sheet metal,  
>when the locking ring is screwed on from above, and then 
>wrench-tightened.   

While you have the installation right, you should be careful about sweeping statements. NMO mounts require either a 3/4" or 3/8" hole, based on the mount you buy. Quite a few people are going to the 3/8" mount as the hole is easier to patch if needed, and the theory is that the structural integrity of the body panel isn't weakened as much. The antenna mounting surface is identical, however.

Be very careful if using a Greenlee punch... punch a test hole. If you get a punch for 3/4" conduit (labeled 3/4" externally), it'll make a hole for 3/4" ID conduit. Needless to say, this is a Bad Thing.

Don't forget a dab of silicon grease in the O-ring channel underneath the rentention nut.

Terry