Home - Techniek - Electronica - Radiotechniek - Radio amateur bladen - QST - Bandpass crystal filter for receiving
KP4HF, Braulio DueIto, of Mayaguez, P. R., operates s.s.b. in the 14-Mc. band with a crystal-exciter rig. He uses a slick receiving stunt, shown in Fig. 1. It simply consists of adjacent-channel crystals used as a filter connection between his BC-312 receiver and the BC-453 "Q5-er." The crystals must be near or on the nominal i.f. of the receiver they are working out of, and the Q5-er is then set on them. The circuit tightens up the bandpass to about 1.3 ke., according to KP4HF.
Fig. 1. KP4HF adds selectivity between his BC-312 receiver and the BC-453 "Q5-er" by using this crystal filter.
Y1, Y3 - Channel 339 (470.833 kc.) surplus crystal.
Y2 - Channel 338 (469.44 kc) surplus crystal