2012/3/13 G3TJP, Dave <g3...@lanks.plus.com> > ** ** > > Hello, Bartek.**** > > ** ** > > Very occasionally you will get a **K2** that won’t calibrate. I have > just sorted one out for another ham here in G-land.**** > > ** ** > > Sometimes a little more capacitance is required, sometimes a little less. > In this instance, C22 was at minimum capacitance and the oscillator was > running on the low side of 4MHz.**** > > ** ** > > I changed C21 from 33pF to 22pF NP0and when the trimmer was set to mid > capacitance, the oscillator was a few Hz off 4MHz, giving me adjustment on > both sides of 4MHz.**** > > ** ** > > It’s easier if more capacitance is needed because all you need to do is > tack an NP0 capacitor across the trimmer or C21. **** > > ** ** > > If about 10pF up or down doesn’t give the required adjustment, consider > replacing the 4MHz xtal**** > > ** ** > > A frequency counter is a real boon in situations like this.**** > > ** ** > > Don’t forget, ALWAYS run CAL PLL and CAL FIL after an adjustment of the > 4MHz oscillator. If the filters look OK, always move the setting up or > down a digit so when you exit CAL FIL the new data for each filter is > stored. Even if the filter setting appears to be unchanged, it will have > an effect on the frequency interpolation and can affect the frequency > accuracy by a few Hz.**** > > ** ** > > 73 Dave **G3TJP****** >
Hello Dave, Thank you for your response. I will try to arrange a calibrated counter and check frequency range of the oscillator and possibly replace C21 or xtal. I do remember to run CAL PLL and CAL FIL every time I change oscillator frequency. 73, Bartek SQ5OBP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
