The schematic shown, is a 2 transistor signal amplifier between 10 MHz to 30 MHz. The BF256C and the BF494 are very popular transistors and are easy to find. The transformer works as insulator and amplifier.
That circuit can give 20 dB gain. The variable capacitor is for exact tuning at the favorite radio station.
The circuit can be powered by a 9 to 12V power supply and because the current consumption is too small like 5mA you can use batteries.