I bought this amp new just before THP closed up shop. I have never used it on 80m due to lack of antenna for that band. I just put up a dipole and tried to use it on 80m. In standby the rf is getting through the amp but in operation mode there is no RF output from the amp as indicated by the Pf meter. Since it only occurs on 80m I suspect a stuck relay in the LPF for 80m. Sound familiar?Thanks, Doug W9LCQ