Class A Push-pull power amplifier

Class A Push-pull power amplifier

During positive half cycle $Q_1$ conducts,So $I_{c1}$ flows
During negative half cycle $Q_2$ conducts,So $I_{c2}$ flows
 $R^{,}_{L}=\left( \frac{\frac{N_1}{2}}{N_2}\right)^2R_L$
$=\left( \frac{\frac{N_1}{2}}{N_1}\right)^2R_L=\frac{R_L}{4}$

$V_{cc}$ is center tapped to $N_1$ in first half cycle ,only $Q_1$ conduct.So effective primary winding is $\frac{N_1}{2}$ same for $Q_2$
 Output current
 $I_{c1}=B_0+B_1cosωt+B_2cos2ωt+....$ 
$I_{c2}=B_0+B_1cos(ωt+180°)+B_2cos2(ωt+180°)+....$ 
$I_{c2}=B_0-B_1cos(ωt)+B_2cos(2ωt)+....$
Total current $I_{c}=k[I_{c1}-I_{c2}]$ 
$=2kB_1cos(ωt)+2B_3cos(3ωt)+....$
Thus even harmonics are eliminated