RX888 external clock mods and use

As delivered the Rx888 has serious thermal problems and for radio science applications it needs an external GPS DO 27 MHz clock.

Paul WB6CXC created a screwdriver-only kit which fixes the thermal problems and adds a ground-isolated external clock SMA input port. Paul describes the installation and use of his kit at: https://turnislandsystems.com/wp-content/uploads/2024/05/RX888-Kit-2.pdf

The kit is available at the TAPR web store: https://tapr.org/product/rx888-clock-kit-and-thermal-pad/.