[Elecraft] Elecraft KPA500 vs Tokyo Hy-Power 1.1Kfx

[Robbins, James]

I am wondering if anyone has an explanation for why the Elecraft  
KPA500 amplifier (500 watts) employs 2 VRF2933 FETs (Microsemi) in  
the final PA where the THP uses 4 ST2933 FETs (STMicroelectronics) to  
generate very similar power levels.  The data sheets for each FET  
indicate that both brands are rated at 300-400 watts, support similar  
mismatches and run at similar voltage maximums.  They have very  
similar specs all together.

Perhaps our amplifier gurus could weigh in here.  Much appreciated.

73,
Jim Robbins
N1JR