I had a similar problem to ZS1REC's with a high 2nd harmonic output from my amp
and a report on 80m from Norway while on topband!
Like many on 160, I use an inverted 'L' antenna which was matched with a high
-pass 'L' network, series C and parallel L, not good for harmonic suppression.
I changed this to a low-pass 'L' matching network, series L and parallel C, and
the problem went away.
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