When operating from 12.5 V auto battery, single TRW PT5757 transistor provides 10 W output. L1 is 4 tums No. 20 enamel and L2 is 10 tums No.20. Both, L1 and L2 has 3/32inch inner diameter. T1 is 4:1 transmission-line transformer made from 3-inch length of twisted-pair No. 20 enamel.
This circuit can be used to amplify small transmitter (1W), to boost the output into 10Watt RF power. The variable capacitors in the input and output is used to tune he circuit to give the lower harmonic distortion on the output. [Circuit’s schematic diagram source: seekic.com/forum]