SOE Wireless Sets: A Complete Guide

Historical Context and the Need for Clandestine Comms

Following the fall of France in June 1940, Prime Minister Winston Churchill tasked the Special Operations Executive (SOE) with the objective to ‘set Europe ablaze’ [2]. To achieve this, the SOE supported local resistance movements and conducted espionage and sabotage in Nazi-occupied territories [2]. A critical component of these operations was the ability to communicate securely with headquarters in Britain.

Wireless operators were among the most vital, yet most vulnerable, members of an SOE circuit. Because radio transmissions could be detected by enemy direction-finding (DF) equipment, the hardware had to be portable, easy to conceal, and reliable. Training for recruits included intensive instruction in wireless techniques, often conducted at specialized facilities [2].

Development and Design

The SOE established dedicated research and development stations, such as those near Welwyn in Hertfordshire, where technicians worked on specialist equipment and camouflage [2]. Much of the clandestine radio hardware was produced by the Radio Communication Department of the SOE at Stonebridge Park [4].

The Type 3 Mk II (B2)

Developed in 1942 by Captain John Brown at SOE Station IX, the Type 3 Mark II—commonly known as the B2—became one of the most iconic clandestine transceivers of the war [4]. The B2 was designed for versatility and was issued to agents, special forces, and resistance groups [4].

The B2 was produced in two primary configurations to suit different deployment methods:

• Suitcase Variant: The initial version was housed in an unobtrusive leather suitcase, typically brown or red, featuring three locks (two simple side locks and one central keyed lock) [4]. This allowed agents to travel through occupied zones without drawing suspicion.
• Parachute Variant: Later in the war, the set was adapted for parachute drops. This version consisted of two waterproofed metal containers marked ‘G’ and ‘H’ [1]. Case ‘G’ contained the transmitter and receiver, while case ‘H’ held the power pack and spares, including headphones and the aerial [1]. These ‘partisan sets’ featured oil-seals for waterproofing in case of water landings and guides for webbing to allow transport by men or mules [1].

Wireless Set A

Also developed by the SOE in 1942, the Wireless Set A was another portable ‘spy radio’ designed for agents in Europe [3]. Like the B2, it was fitted into a suitcase for concealment [3]. The set was a comprehensive kit that included:

• A transmitter and receiver.
• Dual power options: an A.C. power pack (suitable for various voltages and frequencies) and a 6-volt battery power pack [3].
• Essential accessories: a 60 ft. aerial wire, a 10 ft. earth wire, a transmitting key, and low-impedance headphones [3].
• Operational spares: crystals (between 3 and 4 Mc/s), fuses, bulbs, and replacement valves (such as the ATS25 transmitting valve) [3].

Operational Context and Limitations

Operating a wireless set in enemy-held territory was an exercise in extreme risk. Agents had to balance the need for communication with the danger of being located by German radio-detection units. The use of ‘suitcase radios’ allowed for rapid relocation, but the physical bulk of the equipment and the need for a long aerial wire remained significant liabilities [1, 3].

The technical sophistication of these sets—incorporating crystals for frequency stability and adaptable power packs—represented the cutting edge of 1940s portable radio technology [3]. However, the reliance on bulky batteries or unstable local power grids often complicated field operations.

Surviving Examples and Collections

Several examples of SOE wireless equipment have been preserved in museums. The Imperial War Museums (IWM) holds a Type 3 MKII (B MKII) set in its parachute drop cases, illustrating the transition from agent-carried suitcases to resistance-focused supply drops [1].