Well sitting in the dark, without power, on Halloween night, around 21:00 to 21:30 hrs local, quite bored , I dug up the protoype L-600S and gave a listen. At first I heard the switcher in the head lamp and my watch ticking 3′ away. The 60 Hz crud was very low and I could hear the clanking bottles, that is “tweeks” very strong with the loop facing East and West. At times,I could hear the alternator whine of the cars driving by at about 60′ in front of my home. At a North – South  loop direction, a unique frying “hiss” was noted. 

later..sd