David N8DAH has been testing the MAX9812L Mic Pre-amp module on his BITx40. In theory this should improve the gain and signal quality.
David says “So far its working ok at best I sound a bit robotish.”
“I am TXing at around 20w with my amp. I took the audio out through a 10uf dc blocking cap to the bitx40 mic in. I powered the board from a 9v just for testing. R136 is about 1/4. If you use a pre-amp you should adjust this lower or you will cause one heck of a noise on tx. I am not yelling or shouting to get audio out now but not sure I like the audio in any case.
This is without the pre-amp … with the audio files from Michigan to Milford PA websdr
This is with the pre-amp …
David has decided he “might just stick with the slight yell to get the audio out. I like the idea of not having to shout but do not like the audio from this version of preamp”.
Others may think differently. Mike ZL1AXG thought his “more robot-like” voice was more intelligible because it was more “punchy”.
Jeff AD6RH says:
“I used another mic housing with a DPDT switch and wired it so voltage is supplied only when PTT is engaged. I am using a CR2032 3v button cell. It seems to work fine, but I have not compared the stock vs. preamp mic with anyone on the air yet. It definitely has more average power on the watt meter. I can hear some peaks come thru the speaker when transmitting. I may try installing a pot to dial back the gain.”