PA Bias(ClassAB) need help?

Hi friends,
I am a newbie,and want to design PA.I have a question how to select the Bias as following requirement:
RF Output Power: 50 W PEP(Peak envelope power )
Input Drive Level : 1 W
Output Load (RL): 50 Ω
Efficiency (η) > 50%
Bias Voltage: 28 V
Device: MRF9045M
I use ADS to sweep DC curve,there are many selection(IDS) with different Vgs.How to select quiescent point to get 50W PEP？Any formula？

Thanks，

I think it's better to choose Vdd=28V, Idq=0.2A or 0.3A. What is your average power?

No AM-modulation at least 47dBm.And as the photo,The rough prediction of P1dB is less than 50W.Then how to select the Q point?(I use Class AB PA)

Anybody can help me?

.....

Whether do i present it clearly?I mean if i want to get the 50W PEP@1W input,28VDS,which Ids i can select to reach the SPEC.(of course think of linearity)?How to select?