Re: #ubitx SSM2167 mic compressor speaker feedback issue - resolved #ubitx

John <passionfruit88@...>
 

I feed the Vcc of the board from the regulated 5V of the Raduino. I measured its consumption at 2mA which is a very small extra load on the Raduino regulator.

There is a DC blocking cap on the input and output on the board. So no external blocking capacitors needed, and also this is why I had to add the bias resistor.

Correct, the 47KOhms resistor is external, not shown on the picture.

Also not shown on the picture are an axial choke of 100uH between the in pin and the Mic, plus a 1nF capacitor between the in pin and ground to block RF feedback when Txing on the higher frequencies. For me the feedback was noticeable from 15m to 10m. You may not have that issue.

I also have a 10kOhms adjustable potentiometer between the out pin and the original Mic input to the uBitx. Mine is turned to about 80% of its range.

I mounted my board on header pins so I can remove it if I want to, and I extended the header pin on the out side (bottom LHS on picture) past the board to provide and extra connection for the shutdown wire.

I think that the compression and noise gate work quite well on this circuit. When I am silent the background noise does not trigger any movement of the power needle, but it goes up as soon as I speak in the Mic. Also despite showing quite an increase in average power I haven't had any negative comments on my audio. I was told that it was noticeable, but not unpleasant, "good for DX".

And this was with the resistor added for the 4/1 compression.

73, John (VK2ETA)

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