To operate the AN/PRC-77 radio without hearing static, what adjustment should be made?

To operate the AN/PRC-77 radio without hearing static, the adjustment that should be made is to turn the function switch to the squelch position. The squelch function is designed to mute receiver background noise, effectively eliminating the static that can occur when no transmission is being received. By setting the squelch, the radio remains silent until a signal strong enough to break through the squelch threshold is received, allowing for a clear audio output during communications.

Adjusting the antenna type, lowering the volume, or switching to a different frequency may affect overall performance, but they are not directly related to reducing static noise. The squelch feature is specifically meant to manage audio output by controlling unwanted noise from the receiver, making it the most effective adjustment for this purpose.