The coax radio was perfect, exactly what I asked for and what I expected. Use this for a base station install and it seems well done. It definitely works fine. I haven't tested it for signal loss, but SWR is good and the output seems fine.
The simplest way to keep radio on at drive in. Step 1. Put your car in accessory mode. Step 2. Connect your radio to the drive-in’s sound system. Step 3. Connect the battery pack.