Do new VHF radios need to be flight tested? I'm in the process of upgrading all our VHF radios and the local regulator has asked us to follow the guidance/recommendations from ICAO, as we have more or less cancelled many of our local rules. The radios will be used for voice only (including Volmet and ATIS).

What do the ICAO recommendations/procedures say about installing new air-to-ground VHF radios? Do they need to be tested by a test flight? Is there a difference if it is a new installation with new radios and new antenna, versus new radio types but with the same antenna, same frequency and same power output?
Avionics shops almost never test VHF radios in flight. They are almost always tested on the ground with test equipment. The only time I can think of an in-flight test being required is if the technician is trying to troubleshoot an intermittent problem that only happens in flight (such as a faulty connector in the vibration-rich environment of a military transport helicopter).