I found a schematic of the Turner +3 mic online. It is more advanced than you should think as Turner already implemented compression in the late seventies. They called the compression technique “modu-guard”. It is a rectifier circuit that rectifies the audio and sends a DC attenuation signal back to Q3 in the source of the FET amplifier.
To use the CG 3000 antenna tuner for remote operation there is a control box (CTU) that could be purchased from the manufacturer. Some people want to make such a control box themselves. Here is the schematic info.
Thanks to https://sp5kab.pl/pl/sterownik-cg-3000-cg-antenna-tuner-control-unit for doing the work with determining the schematic