M-OV's first indirectly-heated HT rectifiers were the MU12 and MU14. These were in fact the same valve but only a minority of each production batch were good enough to withstand the full rating when tested. These few were labelled MU14. This exhibit came in a wooden box as spares for a Marconi crystal calibrator.The classic envelope is 43 mm in diameter and excluding the B4 base pins, is 103 mm tall.References: Data-sheet & 1040. Type MU14 was first introduced in 1933. See also 1933 adverts. |