11m-10m conversion

[mjd420nova]

The entire transmission system, from amplifier output connector to the antenna should be as short as possible. Forget the attempt to match wavelength, the gain isn't enough to matter. Tune the antenna to get the best match, 1 to 1 if possible. Then use a low pass filter backed up with a tunable filter and you'll be as clean as possible. Ragged amps can create so many harmonics that a clean SWR is impossible.

[Tallman]

Ragged amps can create so many harmonics that a clean SWR is impossible.

That's why the experienced technicians "NEVER" tune with the amplifier in line. If it is tuned at four watts it will still be tuned at 400 watts. You are tuning for the frequency not the power. Low pass filter before the amp and one after the amp will keep your signal clean. Unless you overdrive it.