Re: SSM2176 mic preamp board
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Hi,
I also noticed that the resistors were fitted incorrectly on all of the SSM2167 modules I have purchased.
R1 = 15k is connected to PIN 7 GATE THRS
R2 = 1k is connected to PIN 8 COMPRESSION RATIO
The limiter will be operational, but compression is effectively disabled.
I just swapped them over and then the module behaves as expected.
I also tested with R1 (noise gate -55 dBV) = 5k and R2 (compression 3.9:1) = 50k and the results are close to theory. 
If the noise gate resistor is set too high the output tends to become unstable when there is no input signal. The datasheet recommends a maximum Rgate of 5k.
For my uBITX V6 I have used the SSM2167 in both TX and RX paths and it seems to work reasonably well (see thread below).
I did increase the Rgate above 5k for the RX side AGC, this allows signals still to be heard into the noise floor of the receiver.
?
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