[Elecraft] K3s - 80W on 160

[Gary Smith]

I usually don't run barefoot at 100W and 
don't drive my amp with more than around 
50W. Tonight when I tried running at 100W 
on 160 I was surprised to find it only 
putting out 81W. It puts out incrementally 
till 81W and then even though I can adjust 
the power so it reads 100W on the K3s LCD 
bar and numerical display, the watt meter 
in the P3 and the LP-100A both show the 
wattage stopping at 81W.

With the ATU in or out it gives 81W out on 
160, SWR is 1.28 

All other bands except 6M give around 98W, 
6M gives 87W

Any ideas what might be causing the lower 
output on 160?

Thanks & 73,

Gary
KA1J