Atmospheric noise sir. All transceivers have noise, some are simply more quiet than others. I am seeking a quiet transceiver. The internet has no info on who makes a low noise transceiver. I guess most hams do not care, but with my somewhat poor hearing a low noise clear audio transceiver would make a difference. The best was TS-830S, but it failed and I want a new transceiver that sounds like the TS-830S. I hope I made my post more clear now.