O.K. Lawrence: another line to investigate: I don't give up that easily! 
First, although I am fairly familiar with many Eddystone radios, my knowledge gets a bit thin with their early models, such as the S.358. However, it seems that there were two direct variants of the S.358: S.358/1 (low power AF output stage) and the S.358X: crystal filter. Then there were the '358-derived' models: S.400; S.400X and the S.400B, a.k.a. the Air Ministry R.1448. (The S.450B doesn't 'fit' here: required 12-v.d.c.)
Apparently, external PSUs were required with all these receivers: apart from utility a.c. supplies (200 ~ 250-v), 6-v dynamotor or 6-v lead-acid battery and a 175-v dry battery were required. Since all these receivers are so obviously related, but with various differences - and some of those far from 'minor' - it seems likely that the PSUs would have looked - externally and internally - similar, i.e. not quite the same.
Al.
First, although I am fairly familiar with many Eddystone radios, my knowledge gets a bit thin with their early models, such as the S.358. However, it seems that there were two direct variants of the S.358: S.358/1 (low power AF output stage) and the S.358X: crystal filter. Then there were the '358-derived' models: S.400; S.400X and the S.400B, a.k.a. the Air Ministry R.1448. (The S.450B doesn't 'fit' here: required 12-v.d.c.)
Apparently, external PSUs were required with all these receivers: apart from utility a.c. supplies (200 ~ 250-v), 6-v dynamotor or 6-v lead-acid battery and a 175-v dry battery were required. Since all these receivers are so obviously related, but with various differences - and some of those far from 'minor' - it seems likely that the PSUs would have looked - externally and internally - similar, i.e. not quite the same.
Al.
