On 12/17/2019 11:44 AM, Eric Swartz - WA6HHQ, Elecraft wrote: > We have seen this in rare cases on a few 1500s. It appears to be caused > by the ground connection between the rear RF INPUT SO-239 flange and the > chassis. Or, if the station is not properly bonded. Or coax with a poor shield connection to a connector. 73, Jim K9YC