Where you have I2C SDA/SCLK lines to control an RX or TX unit and wish to remotely control these here is a new angle of how to do it.

Usually these devices are driven from and I2C chip and have a limited drive capability up to about 400pf load only however it we use a PIC to drive these lines a much higher drive capability can be obtained such that we can drive say 200ft up twin screened cable  Plus we can also slow the software down as well if needed. I did a quick test using a 100m drum of 4 core security cable and earthed the other two wires and it worked fine.       I did try to terminate with 100R but the amplitude dropped to 2.5V but I found it worked without them. No drawing is needed.

This was tried on a COMTECH TX.