50 TO 500KHz OSCILLATOR
The following circuit is a parallel mode low-frequency oscillator which makes a great BFO for 455KHz. If oscillator does not start, reduce the value of feedback resistor R5. Increasing R5 reduces the harmonic content, but the oscillator may take e few seconds to reach its full output. For crystals with load capacitance specified between 30 to 50pf remove the 100pf capacitor C2. You can replace the transistor with BC107 or BC547.