Stephan Sandenbergh wrote: >> charts, it is my guess that the loop bandwidth will be in the order of > 1kHz. > Thus, if I can't modulate the 100MHz OCXO at this rate, I will have to > think > of another plan. >
First of all. realize that the modulation bandwidth of the VCO has to be at least 10 times the loop bandwidth and preferrably a lot more in order for it not to seriously decrease the loop damping factor. Hence, 1 kHz loop bw is completely unrealistic for a crystal oscillator. The typical 3 dB resonator bandwidth of a crystal is only a few dozen Hz. This alone restricts the modulation bandwidth to a 10 Hz at best. In particular, in the 10811, the ALC loop will react adversely to fast modulation, and turns out to the be limiting factor. If you want to clean up a crystal oscillator, you need to use a phase modulator following the oscillator. Rick Karlquist N6RK _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
