RL=500V/240mA=2083.33=2K , OPT 2K*2=4K plate to plate
Vg2=250V
Vg=-30V
Vp=375V
Ia=64mA
Rk=30V/64mA=469R
B+ =30+375+10=415V
Rp=500-100V/10mA=400V/10mA=40V/mA=40K
Gm=45mA/35-25V=45mA/10V=4.5mA/V
u=Gm*Rp=4.5*40=180
gain=Gm*RL=4.5*2=9
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Ig2 1.8mA
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Rg2 = 415-250V/1.8mA=92K
Rk' = 1/Gm =1/4.5=222R
Zk = Rk'//Rk =222*469/222+469 = 104118/691 = 150R
Ck = 1/2*3.14*10*150 = 1/9420 = 106uF