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):