Maybe a few words about the technical differences ?in AF and IF AGC.? An audio AGC (better called AVC:? Auto Volume Control) ?just keeps the volume at or below a specified level.? A good IF AGC on the other hand will turn the gain down of the receiver’s IF gain stages so that loud signals don’t cause those stages (including the AF stage) to go into compression (flat topping etc.) causing loud DISTORTED signals to come through. There are good thing and bad things that go with both methodologies.? ?You should decide what you are really trying to accomplish with the circuitry before you start building.

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AVC

Pros:? Simple, easy to understand and implement.? Can be done at the speaker.

Cons:? Loud signals may distort/ overload IF and front end of the radio

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AGC

Pros:? Limits IF and AF compression when implemented properly

Cons:? Is more difficult to build.? Is bandwidth dependent so a loud signal up the band could cause active AGC if the filtered IF bandwidth is wide.

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I’ve designed many commercial AC circuits and they can be more complicated to pull off than the actual receiving circuitry.

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MRM

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