[Amps] 160 efficiency problem

[Lynn]

Hello,

    I am almost finished with the new homebrew yc156 amp.
It works fine on 15 - 80 meters but I am having a problem with
160.

     With 5000 watts in, I am getting about 1200 watts out.

   I have added inductance to the plate and cathode chokes,  changed
(padder caps for the load to 400 pf/ 7.5kv) ,  and setup the tank
several
times.     The blocking cap is a 1900 pf .

    THe other sympton is that grid current is much higher on 160 than
all the other bands.

what am I missing?

TIA for any assistance

Lynn  NO9Z