Manual sweeper source
@8/03, 2015
most of time a manual sweep signal source, or just a wind band VFO meet most requirements to checking resonant, roughly check filter response, etc.
Output to a frequency counter is mandatory to check the exactly frequency. I use the negative oscillator, New negative oscillator , construction with 2sc9018(ft>800Mhz, and a 2sc8550, Ft 100Mhz).
Full schematic (replace the 224 and two variable capacitance diode with air variable capacitor):