Just a thought...is the mic grounded to the chassis of the rig. If memory serves me correctly, Heil supplies a pre-wired harness(cable assy.) for the Goldline. On their website www.heilsound.com
, there was a description of a similar problem w/the fix being a small wire "jumper" to rectify the absence of a chassis ground. Hope it helps...that's a super mic when set up right. Good luck and 73.