For crystal lattice and especially ladder filters, a Q of 10,000 is very much in the "sweet spot" if you are starting off with bare crystals in the Q=50,000 range. Smaller 30-100kHz tuning fork crystals often have Q's around 30,000-50,000 but I don't know the details for the larger tuning fork cuts.
I like the "Serial No 2". I betcha they knew they wanted a 10Hz bandwidth filter and chose 100kHz for the center frequency. 100kHz is occasionally the last IF of receivers that mostly use LC filtering at that stage. It is not unprecedented to also allow a crystal filter there although usually there would be a "phasing control" that lets the shape/center of the crystal filter be tweakable. 10Hz seems too narrow for CW work. But nice round powers of 10 are common in synthesizers. Wonder if this was a cleanup filter in the innards of a synthesizer. Tim N3QE On Sun, Mar 6, 2016 at 2:31 PM, Joseph Gray <jg...@zianet.com> wrote: > Assuming I made the pictures small enough, attached are two images of > an very old crystal filter that a friend found. The strange thing > about it is the bandwidth - 100 Hz. What could this have been used > for, with such a narrow bandwidth? > > > Joe Gray > W5JG > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.