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X-108 Info Howto - Pre Volume Audio Line in / out on Aux Jack (1 Viewer)

Chris Wilson

X-108 Member
30 Mai 2020
Punkte Reaktionen
Hi All

I wanted to be able to run FLDigi to decode CW while still having noise come out the speaker.

On the back of the unit is an Aux cable, which is a serial connector to the CPU, but not really necessary as we already have a micro USB connector for the radio already. I fgured I could use this as a line level in / out as the jack was not likely to be used in the near future.

There is a mic input on the accessory port, so I figured I could parallel that.

The decision was made to make the tip the audio out and the ring, audio in.

Below is the final result.
To do this, I used some shielded audio cable, though you could use thin coax too
I attached a 1uF and a 56K resistor to drop the level of the audio out and isolate the rig somewhat from the PC I was plugging it into

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Above is where I have attached the audio cable to the volume pot. Note I have taken the signal from the top of the pot, not the wiper as we want the signal to be the same no matter the volume we set. The audio cable shield is connected to the ground

Below is where the audio out is connected to the jack. Notice the pointer where I have removed the two inductors that couple the jack to the serial lines giving us exclusive access to the socket without cutting tracks or doing anything else that's permanent

The two chip components the wires are soldered to are the low pass filter capacitors on the auxiliary data input. Perfect for connecting to the jack.. The wire comes from the top of the volume pot and connects to the jack via a 56K resistor and a 1uF capacitor, and connects to the tip on the 3.5" connector
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Finally, jumper the audio input on the accessories socket at the rear of the radio to the ring on the 3.5" jack. You're good to go
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I made a custom lead where I split a stereo 3.5" into a pair of 3.5" stereo with one stereo plug on the ring, and one on the tip. I can simply plug the lead into the jack on the back and into the mic and speaker out on the laptop. Levels are about right.

Hopefully this is useful to someone.


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