This isn't a modification thread, more so a troubleshoot thread. I have a first generation 497 (the one that is loosely based on the ept3600 series chassis with the 2290). It shows perfect modulation on the scope with 110 watts pep according to the lp100a. The issue is that it has no receive, talkback or PA audio. The meter doesn't move when trying to test the receiver at 1uV or 100uV either. It wouldn't be the audio chip being as it modulates? Any help would be greatly appreciated. Thanks -Alex