I took a closer look at the crystal calibrator setup in the 52-Set Receiver this morning and compared it to the crystal calibrator Marconi developed for the Wireless Set No. 19. As you can see, a very similar appearance between them, although the one for the 19-Set is much more compact.
Since, as I recall, the Mk I and Mk II 19-Sets lacked a slow motion drive for their tuning, and this finally showed up with the Canadian Mk III production, I wonder if this slow motion drive was adopted directly from the 52-Set design from Marconi, and pushing this curiosity back a bit further, did any of the Wireless Set No.9 series have a built in crystal calibrator and slow motion tuning drive? Just thinking these two items might have been part of the upgrades Marconi had developed for their Wireless Set No. 9 Mk III that became the 52-Set.
David
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