During World War Two era, Switzerland was working both sides of the
coin, building and repairing equipment for both the Allies and the Axis
powers.

Helium filled balloons with long wire antennas,,, good for pirate radio
too.

I just now did a www.devilfinder.com for,
Becker Shortwave Radios for cars

www.mbzponton.org/valueadded/other/radios.htm
cuhulin