Ceramic Resonator Bfo Circuit

Because the ceramic resonator operates at fixed frequency no tuning of the circuit is required.

Ceramic resonator bfo circuit.

It fits under the radio in the middle of the pcb allowing the batteries to sit undisturbed in their holder. This unit is a one transistor 3 5 mhz rf oscillator whose frequency can be varied. Murata s series number is csbla e 430 509khz. The circuit is extremely stable.

You can then wrap the oscillator output lead around the receiver apply 5 volt and carefully tune your receiver for best quality demodulated audio. Turn the receiver off and then on at any time and temperature the bfo frequency is exactly the same. This two dollar component is similar to a crystal. The resonator is a murata csb 455e.

It needs only the minimum of bfo injection in order not to de sensitise the radio. To demodulate an ssb signal first tune your am radio to and ssb signal. In contrast a vfo with an lc resonant circuit can be tuned over a range of several hundred khz but its frequency stability will depend upon its construction. In contrast a vfo with an lc resonant circuit can be tuned over a range of several hundred khz but its frequency stability will depend upon its construction.

Vfo with ceramic resonator a 7 mhz oscillator with a variable crystal oscillator vxo operates very stably but it allows only a small frequency variation approx. Experiments with a vxo using a 3 58mhz ceramic resonator after trying many different circuits to build a satisfactory vxo variable crystal oscillator using the very common 3 579545mhz american colour burst crystals i was never able to achieve a stable frequency shift of more than about 1khz inadequate for using the vxo as. A 3 58 mhz ceramic resonator sets the oscillator frequency. This circuit was used to stop all the bfo drift.

As mentioned before it replaces the carrier in the receiver that was suppressed during the transmitter s ssb generation process.