Transformer coupled(Class A power amplifier)

Transformer coupled(Class A power amplifier)
Instead of resistive coupling transformer coupling is used

$R^{,}_{L}=(\frac{N_1}{N_2})^2R_L$ 

$N_2=2N_1$
$\frac{N_1}{N_2}=\frac{V_1}{V_2}$  =>
$V_2=2V_1$

$R^{,}_{L}$ is the resistance reflected to $1°$ winding.It acts like $R_c$ in series fed class A
$V_{pp}=2V_{cc}$ 
$I_{pp}=\frac{2V_{cc}}{R^{,}_{L}}$  
$I_c=\frac{V_{cc}}{R^{,}_{L}}$
$η =\frac{V_{pp}I_{pp}}{8V_{cc}I_c}$
$=\frac{2V_{cc}\frac{2V_{cc}}{R^{,}_{L}}}{8V_{cc}\frac{V_{cc}}{R^{,}_{L}}}=\frac{1}{2}$=50%