I have a simplex repeater on top of a 100 foot building, and when I transmit to the repeater to get a response, I will sometimes get a clear response, and sometimes I will get a response of static. Could it be the other radio equipment and antennas on top of the building making interference? Is the transmitter of too little quality to act as a repeater (it's a handheld radio and a repeater controller)? I know that the repeater does not have an issue with transmitting, it is an issue with receiving.
Here are some specs:
Antenna: PCTEL ASP76551
Repeater controller: Suretech Simplex Repeater Controller, SR112
Transmitter: BTECH GMRSv1
Cable used: RG58/AU
Also, two adapters are used on the cable