This page provides information on a arguably better way to use or connect a car rooftop or external antenna to your HT.
The adapter is essentially a .5-inch-high adapter that provides a knurled screw collar method to un-screw the cable from the HT without the need to spin the HT in circles or twisting the cable in circles.
You can leave the adapter in place when you switch to the HT antenna for portable use.
If you are a DMR user who does not have a mobile radio but also one who appreciates the benefit of a rooftop antenna. Also, an SMA to BNC adapter addresses these same issues if you wish to tolerate the taller and wiggle of the BNC connector, not to mention messing with this more complicated approach. So as they say, your mileage may vary…
The stock sma adapter is on the left side.
The adapter on the right has had the male end ground down so that it seats lower into the radio.
The O-ring is used to provide more physical stability as the adapter doesn’t completely bottom out in the HT connector.
The modified adapter with a Nagoya Antenna attached.
These adapters provide the collar to enable no need to spin HT or twist the antenna cable.
SMA Adpters: 2 for $769 currently at Amazon.