My Omni C has the accessories jack in the back, BUT it does not have a jumper plug in it when not using the VFO. There is a jumper in the VFO out and in. That has to be in place when not using the VFO. The Corsair II has a jumper in the Accessory jack when not using the VFO. Also the jumper for VFO out and in has to be in place when not using the VFO. Paul