>When I tune up on 10m, I get arcing on the 160m position on the
bandswitch
>to the frame of the switch. This position switches in the 160m
padding
>capacitor. Nothing in the 160m circuit is connected when it's on 10m.
The
>tubes also get extra warm in the 10m position.
>
You have an autotransformer going for you. With the addition of the
WARC
bands plus 160 meters a coupling problem exists within the tank
circuit.
If you will notice on the schematic of any of the late model 9 band
amps,
they utilize a band switch that shorts out 3-4 of the unselected
positions
Just shorting out the unused part of the Pi coil is no longer
effective due to
the autotransformer action. Even with roller coils, as in the Henry
3-K and
8-K Ultras, half of the Pi roller coil is shorted out with a relay in
addition to
the shorting strap on the roller itself. This problem will show up on
other
bands also, depending on your layout and components. I pulled my hair
out a few years ago when constructing my first 9-bander. Instead of 10
meters
arcing the bandswitch, it was 40 meters in my case. This has nothing
to do
with any oscillations, it is because 160 meters is a LONG way up the
coil
from 10 meters!
GL!
(((73)))
Phil, K5PC
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