Thursday, 9 January 2020

A Simple Speech Processor
(For QRP/SSB Homebrew Transceivers  ) 

Over the last few weeks I had been thinking to build a small AF speech processor to add to my Bitx's microphone. I use a Baofeng microphone for my bitx, so the aim was to design a small PCB to fit inside the microphone enclouser itself. The schematic diagram of the circuit is given here:

The circuit is designed around a low noise OP-Amp. TL071 configured as a microphone pre-amplifier having 40dB gain. The output of it is sampled by an NPN transistor T1 and thus to control compression using the FET. The circuit is too simple but provide excellent results. OM M.V.S. Sarma has kindly produced and provided the following PCB layout for the Baofeng microphone.