Thanks for all the interest and help off line. It's always a trival solution in the end. Seems it was related to the inter-connect coax between the exciter and amplifier, it worked well enough on 80 through 20m, but did not like 15 and above. Swapped it with a similiar 6' coax... Bingo! We're good to go, now where are the sunspots? Ken-W9KB