LM386 low noise alternative?

betwixt said:

Two parallel diodes wired opposite ways around across the headphone is the simplest solution but you MUST add a series resistor or risk the amplifier dumping high current into them.

The trouble with RF AGC is:
1. changing the pre-amp characteristics will alter the detector stage so you need to keep an uncontrolled buffer stage between them. In other words add AGC to a new stage before the existing pre-amp.
2. where do you get the signal strength measurment from? You might be able to extract some RF from the emitter of the detector stage but you would again have to buffer it to reduce it's loading effects then rectify and probably amplify it as well.
3. consider what happens to the perceived signal strength when you deliberately increase the regeneration to receive CW or SSB. The oscillation would be thousands of times stronger than the signal you were trying to measure. The AGC would be the oscillator level, not the incoming signal level.

If you are still there right now, I am monitoring 14.255MHz at the moment but only for a short while!

Brian. (GW6BWX)

Click to expand...

betwixt said:

The frequency was clear when I posted but is now a 'pile up' of stations contacting a station in Spain anyway!

Let me know when you are available.

Brian.

Click to expand...

neazoi said:

With all these changes the volume is nice, sometimes ear-splitting when a good signal is received.

Overall success!
?

Click to expand...