If no manual exists, some hams have traced the PCB and created their own schematics. Search GitHub or Hackaday for “KT-7900D schematic.”
: Some users find the behavior of the selector arrow ( -> ) confusing. When a transmission is received, the arrow jumps to that channel. If you are transmitting on a different channel and a new signal appears, the arrow may jump to the new channel, potentially causing your transmission to be sent on the wrong frequency. To prevent this, you may need to set a specific "Priority Channel" in the menu or manually lock the arrow in place. There is no setting to stop the arrow from moving during reception; it is part of the radio's scanning mechanism. qyt kt-7900d service manual