High SWR on 2m Install

Evening Fellow Tacomians,

This afternoon I received my Diamond Antenna K400SNMO mount which I promptly installed on the hood. I made sure the set screws are touching bare metal and there’s good continuity between the screws and the main body. I’ve also done a continuity check on the mount and it’s passed with flying colors.

However, upon testing the SWR, the values were reading in excess of 3.0. I’ve come to the conclusion that the two antennas I’m using, Larsen 2/70 NMO and a Diamond NR-72, aren’t getting the ground plane they need. Has anyone used a braided ground strap to increase the connectivity for their 2m install? Does anyone have any other troubleshooting ideas that I could attempt?

Finally, in the troubleshooting process, I noticed that if I unscrewed the coax from the transceiver while listening to a net, if the coax was near, but not touching, the connector, the reception was nearly perfect. Thoughts?

73,
Athena

 

Quick update: problem solved. My guess is that the K400SNMO mount just didn’t have a good enough ground plane. A Victory 4x4 hood hinge mount and a custom made cable brought the SWR down to 1.6.

 

Nice! I just went through something similar trying to mount antennas to my Prinsu rack. I had high SWRs, so I bought the Victory mounts and it's flat on 2m and 1.5-ish on 70cm and 1.5ish on GMRS with my Midland antenna.