Components needed,
Surecom SR-628 duplex controller
1- SR-628 cable to match base radio
1- SR-628 cable to match 1/2 watt fixed radio
1 or 2 dummy load to replace the fixed radio antenna and preferably the mobile radio antenna also
2 low wattage HT’s and 1 base station
The base station and antenna are connected as usual and the SR-628 cable will receive audio from the base station and PTT it when the the 628 receives audio from the fixed HT
The other 628 cable connects to the fixed HT and receives audio from it and activates PTT on it when it hears audio from the base station
the base station can be set to any band and frequency but both HT’s should be on low power (hence FRS) and have the same ctcss tones programmed to avoid unintended base station transmitting
so you push PTT on your mobile HT the fixed HT receives that, triggers the 628 which triggers the base station and visa versa
some settings experimentation is needed
and full control of the 628 can be done through DTMF codes from the mobile HT
Regular monitoring of the system is highly recommended