In this video, Peter shows how to modify the audio by changing capacitance at C102 (47p).? The change in audio characteristics applies to both RX and TX.? Peter shows how a slightly higher tone is an advantage while using QRP.
https://www.youtube.com/watch?v=IELJwapv5qs
An alternate method to using capacitors of fixed value is to use a variable capacitor.? This allows trimming the capacitance while listening to audio.? You can select the tone you wish to hear and transmit on.
The following capacitor from Digikey will fit directly into the C103 holes.? Note that C103 is parallel to C102.? If this capacitor is added, remove C102.
I have done this mod and it works on RX.? You have to adjust the trimmer capacitor a bit to get good audio RX; when out of range, things sound a bit strange.? But after initial adjustments, you can fine tune it in.? I raised the tone a bit to pass more of the higher frequency audio.? I have not received any audio reports yet, so I can't speak to results on transmit.
