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Ashhar Farhan VU2ESE's BITX40 is an amazing QRP SSB Radio and has set an unbelievable price-performance point. And many folks are adding new bells/whistles every day (like Allard and Jack). I've been working with a friend of mine, Willy W1LY, and his BITX40. Willy had installed the version 1.13 software from Allard and the HW modifications needed for CW. We have both noticed some interesting RF behavior when the radio first enters TX, even when on LSB (just PTT, with no audio).

After some investigation we are reasonably certain that the burst of RF is coming directly through the balanced mixer which is unbalanced for about 60 mS due to the microphone amplifier stage being switched on for transmit. If one starts with the radio in RX, then C124, the 47uF cap in the mic amplifier is sitting at zero volts. When the radio goes into TX, that cap has to charge up via R127 -- which takes a LONG time.