For our club station we built an outdoor and an indoor unit for the up- and downconverters for satellite communications via QO-100. The indoor unit contains a power supply, the down converter with display and a little crontoller PCB with a relay that allows the user to choose whether to atennuate or switch off the RX audio while transmitting. A third option is to not cut off the RX audio in order to have some guests to follow the whole communication.
The board was built around an existing 12V relay. Some transistors and LEDs where added so that the current state is visible for the user. Also there is a switch that allows to choose wheter the PTT should be controlled by the radio or the up converter should be on permanent TX. The schematics where made with KiCad.
The PCB was assembled using parts from the spare box. LEDs are realized as pin headers so that the LEDs can be mounted to the front panels. Same goes for switches for PTT and SPK control.