The problem: just one panel mounted radio, no audio panel and no room in the panel for one, and my radio transmissions are hard read in the 131 to 132 MHz range.
Resources: A backup radio in reserve, and a extra Bob Archer VOR antenna in the left wingtip.
Solution: Hang the second radio under the panel, connect it to the VOR antenna, and plug a handheld mike into the mike jack. If they have trouble reading me on Com 1, pick up the handheld mike and transmit over COM2.
It's crude, but seems to transmit and receive just fine over the VOR antenna.