Thanks Tom for a very good hint!
I made new coils (2 upper of the three coils) for the choke, I tried to make it
similar as the original as much as possible.
I don't have a grid dipper so I used the "bulb" method for checking the
resonance points.
I found 2 resonance points, 12.530MHz and 18.980MHz. The latter is not very far
away from 17 meters band. I think it is well possible the spurious resonance
was the reason for the failure.
I recommend this test for all AL82 owners before tuning the amp on 17 meters.
73 Timo OH1MDR
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