I usually connect my RTX to the PC in order to manage all the audio via software.
This is my current setup (already working with an FT-991 rig) :
“studio” microphone connected to an USB audio interface (Scarlet 2i4) to enhance the quality of a standard embedded pc soundcard
Rig connected to my PC via USB cable
Footswitch (PTT pedal) connected to the radio using the front RJ45 connector I built.
After setting up all the radio menus in order to get the audio from rear USB port (then from the PC ), I tested the transmission pressing the pedal, but speaking into the mic, no audio SSB modulation was present.
Then I realized something I already noticed when I had the Icom 7300 who gave a similar behaviour: if you use the PTT from the front port, then the rig expects the audio part from the same port, despite the menu settings related to the SSB audio…
It is evident this is not a clever choice from the constructor in my opinion…but “it is what it is…”
Luckily I found a solution (actually it is more a “workaround”, as we, IT addicted, like to call it…): connect the footswitch to the RTTY/DATA rear port of the radio.
So I did with another simple DIY cable; in this way everything is working as expected.
Keep in mind that you can’t use that port for other things unless you remove the cable of the pedal from the rear port….
This is the cable schematics:
The round connector for RTTY/DATA is as seen looking the back of the rig; keep it in consideration while building your cable soldering the wires to the connectors…