Help me fix the noise in a FM receiver with AC/DC rectifier

[Audioguru]

This circuit will retransmit anything what it received.

That is what a regenerative receiver does.

 

[DXNewcastle]

2 questions for you, contau.

Are you powering this circuit with a battery (as in drawings) or a SMPS (as in first post)? If ita a battery, could you please clarify what kind of battery it is? If its SMPS can you please advise what frequency it switches at and what output smoothing it has?

What test equipment do you have? Could you produce some test signals with AM and FM modulation and over a range of frequencies?
It would probably help all of us, including yourself, if we had some test results to consider.
Thanks.

 

[contau]

That is what a regenerative receiver does.

Yes, retransmit signal is oscilator signal inside the circuit.

2 questions for you, contau.

Are you powering this circuit with a battery (as in drawings) or a SMPS (as in first post)? If ita a battery, could you please clarify what kind of battery it is? If its SMPS can you please advise what frequency it switches at and what output smoothing it has?

What test equipment do you have? Could you produce some test signals with AM and FM modulation and over a range of frequencies?
It would probably help all of us, including yourself, if we had some test results to consider.
Thanks.

I have no any test equipment. I do this like a "amateur radio". The circuit receive the local signal and amplify audio, just simple like that. its performent is quite nice.

 

[VSMVDD]

you need to isolate where the noise is

try to supply the control voltage from a battery only {varicap vdd supply}

i think the noise is coming from the vdd to the varicap

you can solve this easy using a choke
as you should have before the resistor

i dont think the rest of the circuit will add to the noise

but add some chokes

100uh + 100nf decouple on both vdd supplies

 

[Audioguru]

Regenerative radio circuits are very noisy.
If the circuit operates as a squelching regenerative radio called Super-Regen then its squelching frequency beats with the 19kHz stereo pilot, the wideband stereo subcarrier and the SCA restaurant music sub-carrier to make lots of noises.