SSM2167 #ubitx


Many years ago I built the BITX40 kit.   It was the one with the red LED display.   I am now waiting for my uBITX to be shipped.   I built a SMM2167 microphone amplifier/compressor on my own board for my X1M transceiver but do not have it any more. I ordered a SMM2167 on a red board from China on eBay.  As suggested I will be putting a 10k potentiometer on the output for adjustments  .Has anyone tested the input voltage from the microphone with a loud "AAAHHH" and then read the voltage on the output after getting good reports from other Hams?  I would like to get it adjusted close before testing with other Hams. 

John <passionfruit88@...>

Hello Lee

I don't have an oscilloscope so I can't give you values.

But I can say is that it is not critical. When I had it all the way up I was told, when I asked, that the voice was "quite readable but the compression could be turned down a little".

So I don't think you risk over driving it to the point of making it unpleasant.

I adjust it to the point of having the power meter at about two third in average on normal talk.

Hope this helps.

73, John (VK2ETA)