22011415 SIMRAD 22011415 RF45X Rudder Reference. The RF45X is a medium duty rudder feedback unit. Mechanically it is identical to its predecessor RF45, therefore it is a repairable rather than a potted throw away item. Electrically it outputs a frequency (pulse width modulated) signal that matches with the J3XX input (AP35/AP50), but it can also output a frequency signal (selectable via internal jumpers) that matches with AP45 and AP9 Mk3. The RF45X can also operate on 24V DC, a useful feature when connected in a stand alone rudder angle indicator system. The unit is mounted close to the rudder stock and is mechanically connected to the rudder by the RF45 transmission link.