Re: coax help
Hello there:
If you need to pass through a metal wall, simply use a good connector: at 1.2 GHz, BNC, N, F and SMA are good. If you need to use a 8"-12" long coaxial cable run inside of the box, use any good flexible or semirigid coax. Only keep in mind that F connectors are specified for 75 Ohm cable (some BNCs, too). I would recommend reading ARRL Radio Amateur's Handbook on how to connect coaxial cable to a connector through a wall for details. At 1.2 GHz, details are important.
One minor problem may be that you may not know the real impedance of your TX inside of the box, and/or antenna impedance connected outside. Impedance mismatch may cause some loss. If you meet some problems in real signal transmission, it may help to tune the antenna, or the transmitter output for the best results.