After a struggle getting WSJT-Set up on the IC-7300, it was time to back up the settings.
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Open FILE → SETTINGS... → General Tab
{Find YOUR Maidenhead Grid Square}
In the lower right, TX Watchdog
Rig:
CAT Control:
Serial Port Parameters
Serial Port:
Baud Rate:
Data Bits:
Stop Bits:
Handshake:
Force Control Lines:
PTT Method:
Mode:
Split Operation:
Soundcard:
Input:
Output:
Save Directory:
Location:
AzEI Directory:
Location:
For more information about why the Left input is chosen and not mono or right, see the INPUT/OUTPUT notes below:
Logging:
Network Services:
UDP Server:
UDP Server:
UDP Server Port number:
Secondary UDP server (deprecated):
Server name or IPaddress:
Server Port Number:
The IC-7300's USB audio interface is technically a stereo device (two channels — left and right), but Icom only uses the left channel for received radio audio. The right channel carries nothing useful — it's essentially silent.
Technical Reasoning:
The radio's internal audio processing converts the received RF signal into a single mono audio stream. When that mono signal gets handed to the USB audio chip (the Burr-Brown PCM2901), Icom's firmware routes it exclusively to the left channel of the stereo output.
What if you make the wrong choice?:
On the Transmit Side:
Output is different — WSJT-X sends audio back to the radio and the IC-7300 accepts it on both channels, so the output side doesn't have the same left/right concern.
IC-7300's BURR-BROWN PCM2901 CHIP:
This is actually a well regarded audio codec chip made by Texas Instruments (who acquired Burr-Brown). It's commonly found in quality USB audio interfaces because it provides clean, low noise audio conversion — exactly what you need for weak signal digital modes like FT8 where signal quality directly affects decode rates.