[Elecraft] KXPA100 160 ATU Issue

[Dave Sublette]

I'm helping my son, K4TOO do some antenna work.  The antenna is up and
tunes on all bands with the KX3 on QRP.  When we put the amp in line, the
amp ATU tunes all bands, except 160.  When we hit the ATU tune button on
160, there are no clicking sounds.  The SWR remains High and the power out
is low, I suppose because the SWR is high and the SWR protection is
shutting down the finals.

The Amp is a year old and has worked well until July.  It hasn't tuned 160
since then. What I am trying to say is I think it is a problem with the
amp, not the antenna.

I'm not sure how to proceed.  I'm away from all my tools, so I am somewhat
limited in troubleshooting options.

Anyone have any suggestions?  Thanks.

Dave, K4TO