"Has any1 got a bridge schematic or link that
   uses synchronous quadrature detectors to read
   Re and Im simultaneously ?"

Hmmm .. you could be in for a difficult time on the
road ahead getting into measurements 'phase measurement'
... it requires exotic test equipment as the *now* ancient
HP 8405A Vector Voltmeter (an all solid-state instrument
introduced in the late 1960's and often found lurking on
eBay for a song) or something as equally insidious (and not
quite as rare but still found on eBay) known as a dual-trace
oscillograph embodied into what we commonly call 'a scope'
...

RF Jim

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