So i recently tested out my Hornblaster PA system.
All the siren modes work great. But the radio mode isn’t.
Whenever i turn the knob, as it approaches 2/3 of its turn, the speaker
gives out a really loud tone (when the handset is pressed). I can still hear my
voice over the speaker, but the tone itself is so much louder and pretty much
drowns my voice. Does any of you guys have experienced the same?
I cant seem to use the PA radio mode at its maximum. 
Any tips and advice is really appreciated.
Thank you
Sounds like feeback to me. I don’t know much about PAs, but is it happening in the garage with the windows down - or does it happen outside with the windows up too?
could it be feedback, a bad microphone ground connection, or a squelsh setting?
My thoughts entirely ^^^^^^^
Audio feedback (also known as the Larsen effect after the Danish scientist, Søren Absalon Larsen, who first discovered its principles) is a special kind of positive feedback which occurs when a sound loop exists between an audio input (for example, a microphone or guitar pickup) and an audio output (for example, a loudspeaker). In this example, a signal received by the microphone is amplified and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again. This is a good example of positive feedback. The frequency of the resulting sound is determined by resonance frequencies in the microphone, amplifier, and loudspeaker, the acoustics of the room, the directional pick-up and emission patterns of the microphone and loudspeaker, and the distance between them