create 1 infantry unit, set desired frequency, set transmit message, choose audio file (1-2 hour lenght ogg format, 50 kbps), enable loop mode, you have just created a radio). in my uh-1 vetnam sandbox im using 5 such radio stations with different tunes. also im using this "beacons" to navigate (for example 31.00 MHz FM transmitting Jimi Hendrix concert and lead you to MASH hospital, 32.00 MHz FM is transmitting Creedence and leads you to base camp etc). also you can create separate channels in AM which will be transmittin vietnam comms for full immersion)