NMO question

[AE7GL]

Most people seem to recommend the 3/4" nmo mounts rather than the ones that use the 3/8" hole. Why? What exactly makes the 3/4" better?
 
 Thanks,

[K0BG]

The 3/8" hole is not waterproof when the antenna is removed. The NMO 3/4" is. Secondly, the smaller one can be easily knocked off. Lastly, the coax comes out of the smaller mount straight down. This makes some installations difficult, and sharply bending the coax for clearance is not a good idea. The coax on the 3/4" mount is at 90 degrees and only requires about 3/8" clearance.

Alan, KØBG
www.k0bg.com

[N3ZKP]

Ditto on everything Alan said.

Lon

[AE7GL]

OK. Well that makes sense then.

Thanks guys,

[KE4SKY]

A 3/8-24 or SO-239 antenna connection is not constant impedence.  This probably doesn't matter very much HF through 2m, but can be significant above about 200 MHz. The NMO, like the "N" connector, is constant impedence and should be used for UHF and higher applications.