When may you test a radiotelephone transmitter on the air?

The correct choice highlights that you may test a radiotelephone transmitter on the air at any time, as long as you are not infringing on designated silent periods. This flexibility is essential for ensuring that the equipment functions correctly, as operators need to conduct tests to confirm that the transmitter is working properly and is capable of sending and receiving communications effectively.

Conducting on-air tests is an important part of maintaining operational readiness in radiocommunications, allowing operators to identify potential issues and resolve them before they cause significant problems during actual communications. The stipulation of avoiding silent periods helps ensure that these tests do not interfere with critical communications by others.

The other options present certain restrictions that do not align with the standard operating procedures for testing radiotelephone transmitters. For example, option B suggests that testing is only permissible with authorization from the Commission, which is not typically the case for routine operational checks. Similarly, while reducing transmitter power is a common practice for certain operations, option D incorrectly limits testing to a specific power level without necessity.