I have a problem about ladder filter: I did an IF chain for an RX on 8,67 MHz. When I put a xtal ahead the IF chain I found the right resonance (a filter with 1 pole!), but if I connect a second xtal without any cap to ground, I found the fo of this filter to be shifted down about 1.5 kHz down. And the same if I put the second xtal on the end of the IF chain after the MC1530 IC! How is it possible? It depends maybe by the caps that I didn't put toward ground?
Can anyone give me some help please?
Thanks.
Alex I0SKK