Suitcase Transmitter-Receiver BP4

The BP4 was designed and produced by Polski Wojskowy Warsztat Radiowy (Polish Military Wireless Unit) in Stanmore UK, in the same time as the A / AP series of clandestine radios, also under the direction and management of Tadeusz Heftman (chief constructor of PWWR and pre-war pioneer of radio amateur in Poland; call sign TPAX).

The B or BP series were ordered by the General Staff of the Polish Army (Division II; in exile in the UK), and unlike the A / AP series, the B / BP series was intended for field use (larger antennas, higher power), mostly for use by the Polish Home Army (AK - Armia Krajowa) - resistance against Nazi occupiers, for internal/domestic communications. Radio has been ordered because of unavailability of that kind of radio equipment from other (UK) sources.

There was two families of the B / BP series (similar like for A / AP-series of PWWR radios). One serie including B1, BP3 and BP5 was for lower frequencies from 2 to 8MHz, and the second family including B2 and BP4, was for wider frequency range from about 4 to about 16MHz. In that time the higher frequencies were considered as more suitable for long range communication - in this case intent was to keep link between Polish Home Army in occupied Poland and Polish government in excile in UK. After satisfying the most necessary needs of the Polish government in exile, these radios were also provided to the Allies (SOE and other special forces), in many cases in the trade exchange for other equipment for special operations.

The design was based on electronic components available on the free market, which in practice meant the US market. This was due to the limited availability of electronic components manufactured by the British industry.

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Elenco delle radio e altri apparecchi della Polish Military Wireless Unit (Polski Wojskowy Warsztat Radiowy); Stanmore, UK (exile)