In article ,
Ian Smith wrote:

Hi,
I seem to have a problem with my kenwood 450s. I can transmit fine on
80 and 40 meters but when I go to 20 nothing plus there is what sounds
like an echo when I try to transmit.

Ian-

Charlie's suggestion to try it with a dummy load is a good idea. That
would (probably) eliminate stray RF as the source of the echo.

It would also provide a non-reactive load, in case your output stage
happens to be oscillating at some frequency determined by the tuner. A
further check on this would require a spectrum analyzer, ham-scan or a
panadapter to see if you are transmitting on more than one frequency.

73,
Fred
K4DII