Re: MAX9814 mic preamp and DC bias capacitor
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uBITX Mic Audio
I think that the rig only needs slightly more gain in the existing Mic PreAmp.? I believe adjusting values to add gain is really all that is needed.? Don't need 40 dB extra gain.
Attached PDF is the Mic Pre-amp used 50 years ago in the SBE SB-33 SF-1 solid state rig that first used bilateral amplifiers.? ?It had plenty of gain and for a Dynamic Mic with significantly lower output than any of the typical Electret-Condenser Mics.? 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.? I used this rig in the '60s and I don;t recall any Pop when going from RX>TX / TX>RX. The "Signal Splitter" was used to isolate the TX and RX Audio.
Dave WI6R
On Mon, Jan 29, 2018 at 10:14 AM, M Garza <mgarza896@...> wrote: Hi Jeff, That is what I did.? I used a 1uf non polarized cap.? It works fine.? It also prevents the board level bias current from going back into the max9814 board. I need to wire in a mic gain control, though.? I have it set to the lowest gain and it picks up a mosquito passing by...
Marco - KG5PRT?
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