[Amps] FL2100B

[c.]

   Well , here we go again .!!
     I got some excellent 572B/T160L 's and have no complaints about 
them at all. However, I seem to still have a suspicious problem on 10 mtrs.
        The output is low, about 400 watts PEP , and the input is very 
suspiciously low at 25 watts. The plate current is at 500 ma. and the HV 
is about 1900. which indicates about 950 watts input and only 400 PEP 
out. This is rather odd, I think.That's an efficiency of less than 40%.
     The HV is 2400 no load and 1900 loaded. The amp had it's filters 
replaced about 18 months back , ( Harbach mod)
  so I'm not too concerned about that.!!! Idle c is 90 ma.
     The input swr is >1.2 so no concern there either. Am I missing 
something that might very well be right under my nose ??? Any guesses 
out there ??? Thanks to all on this reflector for all the help in the 
past, and I'd still like to know how to modify this thing to see grid 
current.!!!
        Have a good day all.!!!!
       carl / kz5ca