I have a President McKinley and a new kl 503. Upon testing these units together I had been using faulty coax jumpers and didn't realize it. I had purchased the jumpers from Amazon and when I tightened the coax to the end of the radio and amp the connection electronically would open the circuit, but when I would just hand snug them the connection would be closed and working. I didn't realize that until after my problem. My problem is this. My president McKinley now only has roughly 100-300 mw. Of rf power output and max swr the radio can read. I'm reading the output from my external watt meter and cannot remember if the swr is also high on the external meter as well. I figured the final transistor was blown, but I purchased another from the online auction place that said would work for the radio. Replaced final and still doesn't work. Any ideas on what I can check or replace? The radio receives just fine and everything else works as it should. Just max swr and under half a watt with output. Any ideas or suggestions? I'm on vacation at the mouse and cannot physically check at this moment.