ICF-SW1 is a miniature LW, MW, SW and FM receiver, also known as a travel receiver or a world receiver, made around 1988 by Sony in Tokyo (Japan). Although these receivers were intended for the civil market, they were also used by spies and agents for the reception of Numbers Stations.
The receiver measures just 11 x 7 x 2 cm, and weighs no more than 225 gr, batteries included, making it one of the smallest in its class. The radio is powered by two internal 1.5V AA-size dry batteries, but can also be powered by an external 3V DC source. By using an (optional) cable, it can also be powered by a car battery.
The image on the right shows a typical SW1 ready for use. It is suitable for the reception of narrowband and wideband AM and FM signals, but not for Single Side Band (SSB) signals, which is regarded by many as a serious shortcoming.
Sony ICF-SW1 receiver:
Nevertheless, the radio is most suitable for travellers, for example for the reception of the (BBC) world service on the short wave radio bands. Likewise, the sensitive receiver was loved during the Cold War by spies and agents, who used the short waves for the reception of coded messages, broadcast by the mysterious Numbers Stations. The SW1 was succeeded in 1994 by the SW100.