Thank you for the comments and suggestions, W1UE and VK3ALB. W1UE-Dennis, I'm not sure what you mean by "matching the Codecs" ... do you mean INP GAIN? As looking at both boxes that is the only setting common between them that is now different (I'll try that). Codec Out is at 255 on both, the default. Otherwise, I have tried everything. I've had these units for more than a year, setup on the floor of my shack to test and evaluate before moving the radio to the remote location. I've also reset the RRC to factory defaults and completely reconfigured it; no change.
I borrowed a complete 2nd system to use in troubleshooting. With both the newer system (serial #3440) and my older RRC (serial #2449), strapped, setup, and configured identically, the new unit works flawlessly, while mine breaks into audio oscillation, pegging the ALC as soon as the PTT button on the Kenwood TS-480 mic is pressed. I've tried both strapping plans as described in the manual; no change. I'm not sure what else to try at this point.
The only difference between my RRC and the borrowed unit is I have the Wireless daughter board installed. Yes, I've tried cabling both the RRC and radio boxes directly into the router and the problem is still present. I'm using local IP's on both. But, since this system worked at one time, I'm not sure what changed in my shack to make my system stop working. I did change the router, but that doesn't explain why the newer unit works and mine doesn't, directly connected or hardwired.
Comments/suggestions are always appreciated. 73, Dennis