As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKING OFF, AIR CREW NOTICED A BURNING ODOR IN THE COCKPIT. ELECTED TO LAND BACK AT DEPARTURE AIRPORT. MAINTENANCE DETERMINED THAT THE GNS 530, GPS/COMM WAS THE SOURCE OF THE ODOR. THE GPS/COMM WAS R & R. ACFT PLACED BACK IN SERVICE WITH NO FURTHER ISSUES.