Saturday, September 28, 2013



This XTAL oscilator was not showing the greater shift. Crystals used was hc69 full size but shift was only 400hz . Very poor shift. I wanted freq shift of few kHz. During reading Internet and practical experience with these Chinese half size xtals, I noticed, that osc requires that feed back capacitance should be low. Earlier I was using 1000pf, 1000pf (c1,c2).So, I replaced them with 100/180 PF. This was the value available with me, nothing particular about it. It clearly showed the shift of one kHz. This shift is good fore CW receiver and transmitter. Body of XTAL metal-can was grounded so due to hand capacitance seen no variations in freq.

     Q1 is bc547, Q2 BF494b and Q3 bc547. It is powered from regulated 12v DC but i generally use 5vdc as source. This gives me enough RF to drive mixers, etc.

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