CHIRP

Have you been able to resolve this on your own since you submitted this?

This is most likely a cable / driver / connector issue. Please refer to these Wiki articles:
CableGuide
CableGuide FTDI OEM Cables
[RTSystemsCablesAndMavericks]
If there's no solution to be found in any of them, please read: How To Report Issues and provide a debug log. Thank you!

Windows notes: If you are using a generic cable with a Prolific chip, you will very likely need to downgrade your driver to version 3.2.0.0.
It can be found at http://www.miklor.com/COM/UV_Drivers.php

MacOS notes: this OS is apparently very picky about USB to Serial cables. From what I heard, only (genuine) FTDI-based cables can be made work.
You must have the KK7DS Python runtime for Mac OSX installed.

Linux notes: Linux generally is quite good with USB to Serial converter drivers.

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