Joe, if I read correct, the BW of this filter is only 10 Hz (cps), not 100 Hz, @ carrier frequency of 100 kHz. Such a low bandwidth is useful to work with very faint signals. The low BW reduces noise, but the received signal must be very slow to pass the filter and the transmitter/ receiver system must be very stable to not miss each other. One such application would be CCW (Coherent CW). But what was the real application of that filter I have no knowledge ...
Arnold, DK2WT Am 06.03.2016 um 20:31 schrieb Joseph Gray: > 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.