Season's Greetings to all! I have heard that corona discharge is audible at a some ultrasonic frequencies. If this is true, does anybody know what range or specific frequency? 73, Charlie, N0TT -- FAQ on WWW: http://www.contesting.com/FAQ/topband Submissions: topband@contesting.com Administrative requests: topband-REQUEST@contesting.com Problems: owner-topband@contesting.com