Troubleshooting aerial on 2007 VE

[Pawly450]

Since installing an aftermarket head unit I've got poor radio reception, especially AM. As part of troubleshooting I unscrewed the roof aerial and then checked for continuity between the centre aerial plug in the dash and the aerial base (female thread). Result was open circuit. My very basic knowledge tells my I should have continuity between these two points. Does anyone know if I'm right? The reception with the original stereo was fine so It has me thinking maybe I might have damaged the cable during all the messing around with the wires when working on the new stereo install.

 

[mycarsound]

What new unit did you install? Did it come with a Farka antenna adapter or did the original antenna connector plug directly into the new unit?