The Murphy B40 Series of Naval Communications Receivers are receivers for shipboard use (British Navy & submarine). There were four variants manufactured, which accounted for the last digit of the pattern number being 1, 2, 3, or 4. In other markets (notably the Royal Australian Navy) these were known as Murphy B40A, B, C, or D.
Should you have any questions on Murphy B40 receivers, please do not hesitate to contact Shawn Williams ZS1SBW at wotalark"at"gmail.com (please take care to replace the "at" with @)
Model Notes:
http://www.portabletubes.co.uk/boats/murphy3.htm - detailed information about history, performance, controls, design manuals, and schematics/diagrams.
http://www.radiomuseum.org/r/murphy_b40_b_40.html