In article , G.R. Patterson III
wrote:

As most of us have been doing these days, I spend a fair amount of flight time
listening to 121.5. This frequency has always had some sort of low level hiss
and crackle on it that I don't hear on other communications frequencies. Does
anyone know what causes this?

You can get rid of that... turn the squelch know until you don't hear
anything. :-))