Tuesday, February 22, 2011



Variable frequency oscillator uses two numbers of BC548. For 40 meter band VFO oscillates form 2.567 MHz to 2.667 MHz which on mixing with 4.43 MHz generates 7.0 MHz to 7.1 MHz. If you have a frequency meter it is easy to calibrate the VFO, otherwise connect a 2J gang condenser in parallel with VFO coil and adjust it to receive ham stations. VFO is fixed inside a small aluminum box.

VFO - Variable frequency oscillator

1 comment:

  1. thanx karan for the circuit. I am right now working on building a 7Mhz transceiver on my own. I have already made the bandpass filter, af amps, prod detector and power amplifier. i have used 4.43 Mhz crystals in a ladder ckt. I am facing a few prob with respect to the vfo part. Hope that this circuit works. My id is deepakkumar88mail@gmail.com. pls get in touch .