My VX-5R like many others had a chronic loose antenna.
I bought a male smc connector with a 6 point nut for 3.00 at a hamfest and replaced the old spanner type nut with the 6 point. I also used the small washer that came with the new connector under the nut. Using a 8mm - 6 point Craftsman thinwall socket and a firm but gentle twist is all it takes to snug the nut down. It has been over 2 months and several antenna swaps and the connecor is still tight.
This simple and cheap mod has made the radio much more enjoyable and no more worry about blowing the finals.
One final note: The socket needs to be a quality 6 point thin-wall. The Craftsman 12 point and even their 6 point nut driver would not drop into the antenna recess. I imagine any higher quality 6 point socket should work just fine.
Good luck and 73
| 
