The circuit shown below is useful for increasing the reception of multiband transistor radios. The circuit increases the reception of CW and SSB band. This circuit has a hartely oscillator frequency range across the broadcast band. The circuits harmonics extend to higher SW frequencies, it provide good reception of CW and best reception for SSB signals.
The capacitor C2 is for frequency adjustment place the circuit near the radio for good reception. Fix the circuit in a plastic package antenna is not essential. You can also use this circuit for code practice in 15 to 20 feet range diameter from the radio for that you have to connect 10 foot antenna and insert key switch in series with power supply (9V battery).