[Amps] Drake L-4B fan - too small and too slow?

[John]

Hi  Allan
   
  I just sold my L4 and  anything key down at or over 1kw input caused the plates to glow very orange.
   
  More cooling is needed if one wants to run the drake amplifier  at a high duty cycle or at more power than what the manufactures manual recommends which is a input at 1kw cw. 650 watts output.  My L4 could put out 1350 watts with 100 watts drive. And kept my feet warm.  This is something I miss. My new commander fails miserably in the heater dept.  At 1500 watts on RTTY I have to plug in the electric heater to keep warm.  Must be a  more efficient design.
   
  A blower on the rear would likely work OK.  But do not forget about the back pressure requirement.  The stock blower should be removed and tubing installed to duck the air.
  At the least the blower impeller should be removed.  This should create a back pressure requirement that exceeds what is required when pressuring a chassis without having to force air thru the existing blower hardware.

john kb9tc