Thx.The problem is that this is not an FM receiver, it's a cheesy
AM receiver that manages to crudely demodulate FM as well.
It has no rejection of CW, AM or burst RF energy that is
in-band.
So it does a swell job of picking up any power supply
harmonic that comes along.
Look for ringing on supply edges and add a snubber
across any diodes / switches. Put ferrite beads on
the power and return legs at the supply. Put the
supply or the radio in a can. Etc.
There is no loop so it is not a PLL.Thx.
i think this circuit makes a simple PLL in case it's FM receiver. I made it and play well.
why not? i prove this is a PLL.There is no loop so it is not a PLL.
The transistor is an AM detector. It poorly detects FM with "slope detection".
AM has amplitude changes and noise also has amplitude changes.
An FM detector detects frequency changes and ignors amplitude changes.
voltage controlled oscillator and a phase detector is inside transistor. The varicap Ccb will change due to audio feedback, so the oscillator fre will be changed --> creat a VCO.A Phase-Locked-Loop has a voltage controlled oscillator and a phase detector. This simple circuit does not have them.
No. It is just a simple transistor junction. There is nothing else "inside" the transistor. And you've chosen a transistor with a particularly poor gain-bandwidth product for radio frequencies, at 250MHz it will struggle to give you the voltage gain which we'd expect from the front end of a receiver.voltage controlled oscillator and a phase detector is inside transistor.
I mean voltage controlled oscillator and a phase detector are inside transistor circuit. oscilator frequency depends on audio signal feedback from E pin.No. It is just a simple transistor junction. There is nothing else "inside" the transistor.
I think the transistor multiply the fm signal to oscilator signal --> "phase detector". The output signal of this "phase detector" will moved to emitter and pass over lowpass filter. At here, lowpass signal will reverse to base. This circuit will retransmit anything what it received..There is no phase detector.
In essence, it's an emitter follower using a transistor beyond it's design frequency and with a strange and inefficient varicap tuned circuit at it's input.
.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?