Hi,

I made a calculator to help out with some numbers as a google sheet at this link. This is publicly editable, but I will change that after a few days have passed.

https://docs.google.com/spreadsheets/d/1H0mCZAM0MhHkbXDTtomCzDjg0lkKSL3_eBUJIuL1NSY/edit?usp=sharingI would really appreciate some feedback and whether I made any mistakes. The sequence of calculations is as follows:

Desired output power per carrier (Editable) = 2W

Number of carriers (Editable) = 5

Characteristic impedance = 50 Ohm

Output rms voltage swing per carrier = Square_root(2W x 50Ohm) = 10V

Total output voltage swing = 10V x 5 (carriers) = 50V

Output power required of class-A amplifier; Pout = (VxV)/R = 50x50/50 = 50W

Max. achievable efficiency of class-A amplifier = 50%

DC power consumed by class-A amplifier ; P_tot = 50W / 50% = 100W = Power that will be dissipated by the heatsink

Drain supply voltage (Editable) = 50V

Rough estimate of Quiescent drain current = DC Power / Supply voltage = 100W / 50V = 2A

Load line resistance R_L = (VDD*VDD)/(2*Pout) = 25 Ohm

Max allowable Junction temperature (from Datasheet) = 175C

Case to junction thermal resistance (from Datasheet) = 1.1 C/W

Max allowable case temperature; T_case = 175 - (P_tot*1.1) = 175 - 110 = 65C

Ambient temperature (Editable) T_ambient = 30C

Target thermal resistance of Heat-Sink = (T_case - T_ambient) / P_tot = (65C - 30C)/110W = 0.4 C/W

Now 0.4C/W is probably difficult to realize, but these are the numbers for calculations' sake.

Does this look correct