I used a Female N connector from the 800 MHz repeater. I drilled an hole in the back and solder directly to the center pin of the connector and just clamped the ground.
Modification for Base Radio
This page shows the PA modification using a fixed station. The electronics is the same for base and mobile. The last three 220 MHz repeaters I made using a repeater shell, I added an Hamtronics LAP 2-40 kit on the GE Master II repeater heat sink. Hamtronics publishes 45 watts output with 2 watts input but I always get 70 watts using more drive and on the large heat sink, you can run the repeater at maximum power continuously for weeks with out damage.
The repeater on this page was designed to us and external amplifier that requires 4-10 drive . I will use the filter in the external amplifier so I do not have to add the filter shown on the Mobile page. If you choose to use the repeater without the external amplifier you must install the filter which will lower the power to about 38 watts.
I used a Female N connector from the 800 MHz repeater. I drilled an hole in the back and solder directly to the center pin of the connector and just clamped the ground.