[Uhehner]

Vhf antenna cables are usually not very long. Therefore I would trace back down the antenna cable from where it comes into the helm area and look for a white 1/4" diameter cable with a PL259 connector on it. It will probably go into a small box with two other PL259 connectors and red and black 12 volt supply leads. The other two white cables will go to your radios. This would be for an automatic switch, not a manual one. A manual switch would not have 12 volts connected to it and would be in a location where you could see it and operate it. Good luck. Capt. George