• Year
  • 1942
  • Category
  • Military Transceiver (TRX)
  • Radiomuseum.org ID
  • 301679

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Tubes
  • 4
  • Main principle
  • Transceiver; ZF/IF 470 kHz
  • Wave bands
  • Wave Bands given in the notes.
  • Power type and voltage
  • Line / Batteries (any type) / 97-140VAC or 190-250VAC or 6DC Volt
  • Loudspeaker
  • - For headphones or amp.
  • Power out
  • 0.05 W (undistorted)
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Spy Radio Set Type 3 Mk. II - Marconi Co. Marconiphone,
  • Shape
  • Miscellaneous shapes - described under notes.
  • Notes
  • The British Type 3 Mk. II, commonly known as the B2, is arguably the most well-known spy radio set used during WWII. It was designed in 1942 by (then) Captain John Brown at SOE Station IX, and manufactured by the Radio Communication Department of the SOE at Stonebridge Park. The set was issued to agents and resistance groups and special forces operating on occupied territory. The official designator is Type 3 Mk.II but the radio is also known as Type B Mk.II, B.II and B2.

    The B2 came in two flavours. The initial version came in an unobtrusive leather suitcase that allowed an agent to travel inconspicuously. This is the most well-known variant. Later in the war it was dropped by parachute in two water-tight containers that were more suitable for use by resistance groups operating in the field.

    The radio set consists of three units: a receiver (RX), a transmitter (TX) and a Power Supply Unit (PSU), plus a box with spares and accessories. When mounted in the suitcase, the transmitter is located at the centre top, with the receiver mounted below it. The PSU is at the right in such a position that the two other units can be connected to it. The spares box is generally positioned at the left, with the Morse key mounted on its lid. When operating the B2, the lid of the spares box should be placed on the table, so that the Morse key can be operated.

    The Type 3 Mk.II (B2) was relatively small for its day and produced an HF output power of 20 Watts. Nevertheless, it was too big to carry around unobtrusively especially when travelling by public transport. For this reason, later radios, such as the Model A Mk. III (A3) were made much smaller, albeit with a limited frequency range (3.2-9.55 MHz) and reduced power output (5 Watt).


    For the transmitter, external tank coils are used. Each coil is suitable for a limited frequency range and should be inserted into a 6-pin socket just below the meter. In order to cover the entire frequency span, four coils are supplied (L1 to L4) that each have two sides (A and B). Besides the correct coil, the WAVEBAND selector should be used to select the appropriate range.

    The following frequency ranges are available:

    L1-A: 3.0 - 4.0 MHz
    L1-B: 3.75 - 5.25 MHz
    L2-A: 4.5 - 6.25 MHz
    L2-B: 5.5 - 7.5 MHz
    L3-A: 6.5 - 9.0 MHz
    L3-B: 7.0 - 10.0 MHz
    L4-A: 9.0 - 13.0 MHz
    L4-B: 12.0 - 16.0 MHz


    The receiver is usually mounted below the transmitter and is the smaller of the two. The entire coverage from 3.1 to 15.2 MHz is divided over three ranges that are selected by the WAVEBAND-selector at the left.

    To the right of the band-selector is the tuning knob that has two wheels: one for coarse and one for fine tuning. Above the tuning knob is the scale readout that has a magnifying plexiglass lens over it.

    Power Supply

    The Power Supply Unit is normally mounted to the right of the transmitter and receiver in such a position that the two modules can be connected directly to the corresponding power socket at the front. It allows the radio set to be powered from the mains and from a 6V battery.

    Spares kit

    The spares kit, also known as the accessories box, is a high storage box with a removable lid, approx. the same size as the power supply unit. In most cases, the lid has two mounting holes for the Morse key, but with some B2 sets, the lid had a mounting bracket for a slide-on Morse key."

    Text Information from the Crypto Museum.

  • Net weight (2.2 lb = 1 kg)
  • 34 lb 0 oz (34 lb) / 15.436 kg
  • Mentioned in
  • -- Collector info (Sammler) (Louis Meulstee, Wireless for the Warrior, volume 4 ISBN 0952063-36-0, September 2004)
  • Author
  • Model page created by Gary Cowans. See "Data change" for further contributors.

 Collections | Museums | Literature


The model Spy Radio Set Type 3 Mk. II (B2) is part of the collections of the following members.