The Q15 collector voltage is a bit low to handle loud signals. I changed R114 to 180K and
added another 180K from Base to Emitter. This increases the collector voltage from around
1 Volt to about 3V. The hiss reduces a bit due to the change in time constant of R114 and
C118. You can add a parallel cap of another 100 or 150pf to roll off highs above 3 KHz.
Now the audio is better and more mellow in my BITX40 #63 with analog VFO.
73
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Raj, vu2zap
Bengaluru, South India.
Raj vu2zap