The exp mast antenna was grounded via the base to metal, without ground no reception.
The tuner is the Directed HD radio DMHD-1000.
No idea, there is no schematic available and I haven't poked around enough to have an answer for that.That power supply, does it have any small value bypass caps across the 'lytic filter caps? or any small value caps dumping RF to ground in that thing.
More pieces to this puzzle:
I remembered this morning he has his windows tinted, most likely metallic based. I know his USB GPS antenna would not work in the back inside or outside of the car, it had to go up front to work.