You cannot use a simple $5 USB programming cable. The CM340 uses a proprietary 2.5mm and 3.5mm dual-jack connection on the microphone port. This requires a RIB (Radio Interface Box) —a powered level converter (Motorola part # RLN4008) or a "RIB-less" cable that mimics its circuitry. Even then, most RIB-less cables only work with genuine FTDI chips, not the cheap clones.
You cannot use a simple $5 USB programming cable. The CM340 uses a proprietary 2.5mm and 3.5mm dual-jack connection on the microphone port. This requires a RIB (Radio Interface Box) —a powered level converter (Motorola part # RLN4008) or a "RIB-less" cable that mimics its circuitry. Even then, most RIB-less cables only work with genuine FTDI chips, not the cheap clones.