I figured out the problem : Even though I was hooking my audio directly into the mic input of the CM108 chip, a low pass filter was clamping all the high frequency signals to ground, I just had to desolder an L5 as this link shows:

http://m3h.com/usbfob-119.pdf

I was looking at other guides, which had sound fobs with no low pass filter already in it.

kdw0hb

On Tue, May 3, 2016 at 8:34 AM, Skyler F <electricity440@gmail.com> wrote:

I just put together a modified sound fob by taking a 10µF capacitor to the divider of 47k and 68k resistors and then to the microphone input of the sound fob, but I am getting the lack of high frequency noise error when I plug my fob into the radio. A DMK URI works fine. Has anybody else had problems with these sound fobs?

73
kd0whb

Skyler Fennell

amsatnet.info

KDØWHB

electricity440@gmail.com