uBITX Mic Audio

Dave WI6R thinks that the rig only needs slightly more gain than the existing Mic PreAmp and that adjusting values to add gain is really all that is needed.  He doesn’t think it needs 40 dB of extra gain.

He has resurrected a Mic Pre-amp design used 50 years ago in the SBE SB-33 SF-1 solid state rig that first used bilateral amplifiers.   Bilateral amplifiers are used, of course, in the BITx transceivers.
This design had plenty of gain and worked with a Dynamic Mic with significantly lower output than any of the typical Electret-Condenser Microphones used today.   Also note that the Mic PreAmp was powered only when the rig was in TX and a simple diode was used to shut off the Mic PreAmp in RX with the same TX voltage.
Dave used this rig in the ’60s and doesn’t recall any “pop” when going from RX to TX or vice-versa. The “Signal Splitter” was used to isolate the TX and RX Audio.

Raj, VU2ZAP responded suggesting that simply decreasing the value of R63 would give you more gain!

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