Wikipedia:SCR-203

The SCR-203 was a U.S. Army radio transceiver used during World War II and designed to be mounted on an animal pack saddle.

Specifications
The SCR-203 was a low power, short range, portable command set designed to clamp onto a Phillips pack saddle for animal-pack transportation and operation. It was used primarily by the cavalry, and field artillery. It consisted of the BC-228 transmitter, the BC-227 receiver, and BC-235 control box and could transmit 7.5 watts AM voice, MCW, or CW for a range of approximately 30 miles. Its radio frequency coverage was approximately 2.0 to 3.0 Mhz. The unit was powered by various battery packs and a GN-35 hand cranked generator and used a 25 ft whip antenna.

History
The mule-packed radio concept dates back to before World War I, but due to the decline of the Horse Cavalry and the miniaturization of radio components, the SCR-203 was the last of the U.S. Army's radio sets designed to be animal-mounted. The SCR-203 was replaced by the SCR-245.