Fascinating, thanks.Once I became technical manager at MIMCo I stopped all that 3-phase nonsense. It had never made sense to me - after all, the Crusader required less power than our kettle at home and we didn't have a 3-phase supply to the house. All new designs started for me had to be single phase devices capable of running from the ship's emergency generator supply. The Challenger, our most powerful transmitter was just the latest and last "traditional" (i.e. manually-tuned) design the company produced.
I suspect that MIMCo went down the 3-phase path accidentally, in the early days post-WW2, simply because design of their transmitters (and most other equipment) was carried out by engineers of Marconi Wireless Telegraphy - producers of high-power broadcasting, point-to-point and military transmitters. They were familiar with such techniques and would have felt happier using existing designs rather than starting from scratch. Big commercial organisations can resemble VLCCs in that it takes a lot of time and effort to turn them round once they have adopted a policy. MWT, with its inherent assumptions - that because they were the first, they were the best and could not be wrong - was an almost unstoppable force.
I failed to stop Conqueror being 3-phase but persistence made it the last of our transmitters to be designed that way. Everything from Commander onwards was single-phase but we still had little success in persuading many builders and owners of newbuilds to connect the radio room supply to the ship's emergency generator - they were even more difficult to convince than MWT. If it wasn't a regulatory requirement, it wasn't going to happen as far as they were concerned.