455khz Ceramic Filter Oscillator

The local oscillator is set to 100 455khz and when the mixer mix the rf 100mhz with the osc 100 455mhz the product will be 455khz and lots of other frequency products.

455khz ceramic filter oscillator.

It filter away almost everything except 455khz 10khz. Waveform is a mildly distorted sine wave. 3 used transistor bc548 9 volt supply voltage rf signal is produced with 455 khz ceramic crystal. Oscillation frequency is dependent on the true resonant frequency of the ceramic filter.

Nand gate u2a is the modulator and provides a 100 square wave modulated signal. Nand gate u2b buffers the original unmodulated signal and its propagation delay ensures that its output is in phase with the output of u2a. Murata makes the cerafil r line of ceramic filters some of which are designed for use at 455khz and 450khz. The objectives of if alignment are to ensure that all tuned circuits in the if stages are tuned to the same frequency and that this frequency is the correct frequency usually 455khz.

And it is here the ceramic filter comes handy. The filter s center terminal normally grounded is connected to the current limiting resistor. Inverters u1d e along with ceramic resonator x1 form a stable 0 5 455 khz oscillator. Homebrew 455khz ceramic if filter so today after reading some more of soldersmoke global adventures in wireless electronics and feeling somewhat enthusiastic about advancing some projects i went out to my work bench and soldered up a test rig used to determine the motional parameters of crystals and in my case ceramics.

Oscillation is near 455 khz stable within a few hz. For example the sfpla450kd1a b0 has a 6db bandwidth of 10khz designed for use with am stereo receivers.