>>> Don't use a high Q bandpass filter as its phase shift tempco will be >>> relatively high. >>> >> What do you think if I could find FM radio IF filter somewhere (10.7 >> MHz) and tune it to 10 MHz? I don't know if there's tunable filters >> available anymore because any new ones seems to be ceramic. But maybe >> from some old radio could have tunable one (wishful thinking in Finland, >> thanks to "recycling" of the electronics). >> >> > Using a 10MHz bandpass filter isn't usually a good idea unless the > temperature doesn't change too rapidly and the filtered output is phase > locked to the stable frequency source. > The phase shift tempco of the bandpass filter then isnt too critical as > slow changes in the filter phase shift will be corrected by the phase > lock loop. > Even so you don't want too high a Q or the filtered signal amplitude > will change too much over temperature.
You should be able to lower the effective Q value by use of external serial or parallel resistor. A parallel resistor will add some capacitance, but detuning the frequency should also require some additional capacitance so it should work fine in combination. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
