Eric, Bob, and many other good folks, Success!!!! This being a holiday, I could not get RG400 to replace the cable from the TX to the connector on the back of the repeater, so I built a shield to completely enclose the cable. I also wrapped aluminum tape around the receive cable in the chassis. Lo! And Behold! No more desense!
My sincere thanks go to all of you who have helped me through this most vexing problem. The repeater will be far more useful now. Best 73s to you all, JohnT AF4PD
