Re: ND6T AGC Troubleshooting
Rich,toggle quoted messageShow quoted text
You are correct, it is better to have AGC reduce gain at RF or in one of the IF amps.
The audio pre-amp at Q70 of the uBitx (or Q16 of the Bitx40) is the weak link,
restricting available dynamic range if AGC attenuation occurs after that audio pre-amp.
However, take another look at the ND6T AGC, it attenuates the RF as it comes in from the antenna.
Not unlike your design, but using FET's instead of op-amps.
Simple and effective.
Would be interesting to do an A/B comparison of your implementation vs the ND6T AGC.
Lots of variables here regarding dynamic range of the attenuation, attack and release times, distortion, ...
On Sat, Jan 12, 2019 at 08:46 AM, WA6PXC Rich wrote: