I'm putting the finishing touches on my brand new hf portable ham shack that consists of a Yaesu FT-891, Ameritron ALS 500MR, LDG 1000PROii and MFJ-828, along with other supporting components. The mockup, once fully debugged, will be transferred into my semi truck and feed into a center fed, center supported aluminum tube dipole mounted atop a military surplus QEAM mast. So far, things are working well and I'm getting good signal reports while using this mockup in the gazebo behind the house, powered by my Dodge dually parked next to it, and all the cases grounded to a single point, then extended to a ground rod in the dirt. Now, once I transfer to its final installation point, the chassis ground rod goes away. In preparation for the final install, I tested that connection back to the battery ground post, and the result appears to be a tremendous ground loop into my headphones. I hear my transmitted voice in a very muffled and distorted way that increases when the output wattage increases. Perhaps RF? Not sure yet. Full disclosure: I'm still testing for cause and solutions on the weekends when I'm home but the idea just came to me to use a 0.5uf high voltage capacitor (like a motor start capacitor or doorknob capacitor) between the ground point and the battery terminal or vehicle frame however, my knowledge of electronics and DC vs RF grounding is less then adequate to know if I'm barking up the right tree or not. Ultimately, I need to ground these radio chassis to something...perhaps a rubber static strap to the pavement below? I dunno. Ideas?