Electrically, at the USB interface, the Pi3 and? the Pi4 are identical. The only difference is the location of the USB ports to accommodate the new location of the USB ports in the Pi4.? If you plug a SHARI Pi3X (U or V) into a Pi4, The SHARI case blocks access to the Ethernet jack.? The same situation occurs if you you plug a SHARI Pi4X into a Pi3.? If you do not need the ethernet connection (i.e. you connect to the internet using the Pi WiFI) then they are interchangeable.? Also, you can use short USB extension cables.? In fact, you only need one cable as one USB connection is used to operate SHARI with Allstar and the other is used to program the radio in SHARI.? Either will provide the necessary power to SHARI.? Looking at any SHARI from the top with the USB ports on your left and the antenna on your right, the USB port closest to you is for Allstar and the other is for programming.
The only difference between a PiXU and a PiXV is the RF chain - thus the SA818 radio module, the output low pass filter and the antenna are different.
Steve - N8AR
Steve-N8AR