Thanks to a kind offer by Philip Thornton-Evison, we have received the correct handbook for the unit on loan, for copying and return.
Philip's book is for the Pioneer Gen-E-Motor BD-12-A, which is identical to our unit.
The unit was originally intended for operation of Wireless Set No 12.
Peter
-- Peter A Forbes Prepair Ltd, Rushden, UK snipped-for-privacy@prepair.co.uk
formatting link