Fig. 3-8. Crystal variable resolution filter.

its base to emitter Q420. A feedback winding on T424, to

is tuned to 5 MHz and couples the signal to the 5 MHz IF

the hose of Q420, provides the neutralization far the col-

amplifier Q460. Diode D454 in the collector load of Q450

lector-to-base capacitance.

improves the overload characteristics of the amplifier. Out-

put of the 5 MHz IF signal is applied through an insulated

The 75 MHz IF and the output from o crystal controlled

connector J470 to the input of the variable resolution am-

70 MHz oscillator Q440, are applied to the mixer amplifier

plifier.

Q450. The collector output circuit of Q450 is T454, which

Fig. 3-9. Crystal filter, equivalent circuit and impedance response

Fig. 3-8. Crystal variable resolution filter.

curves.

3-9