I have just built a copy of the G5REV Microhub, but it will not receive anything I transmit, although the RX lamp in the 888 is coming on when I tx with another rig. I have checked the 888 is the same on TX and RX and the CTCSS code is correct… I can connect and disconnect various numbers with the unit in USB Low ( No12 on Putty ), but it just transmits a blank carrier if I put it in the USB High mode where it is meant to be. I bought the CM108 board already wired and modified.
Sounds like the tx out audio isn’t actually making it to the radio. If the mechanics of everything on RX works fine and TX works except output audio, your issue is likely electrical.
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Can you hear any audio coming from the 888? To check this, you can use a small speaker or a set of headphones. If wired with the conventional colours, the audio out from the 888 will go to the yellow cable (mic in) on the CM108. Normally via a single resistor or a pair in a voltage divider configuration. Listen for audio in the circuit before and after the resistor(s). Do you have a good earth path from the radio? This 5th wire is often forgotton. I take a wire from one of the ground GPIO pins on the Pi and connect it to the radios earth. Has the 888 been wired so that its volume control remains active. You may need to increase the volume on the radio if it is.
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