The MD41-24P( ) is a bulkhead mounted remote transfer relay unit specifically designed for switching a CDI or HSI Indicator between two aircraft radio navigation systems. The remote switching unit is designed to be used with the companion MD41-1XXX series Annunciation Control Unit (ACU). This pertains to GPS systems where the user desires to share a common CDI or HSI between an existing NAV system and a GPS system.

The 24 pole unit features eight relay pairs consisting of 3 poles per relay pair. Each relay pair can be activated individually by either voltage or ground keying or as a group by ground keying.

Other design features include:

• Interlocking of transfer relays utilizing one pole per relay pair for failure monitoring. (This feature provides indication that all relays have power applied to their activating coils. It does not monitor all relay contacts or coils.)
• A special ILS override that will automatically force the MD41-24P( ) to switch to NAV mode when the NAV (VOR) receiver is tuned to an ILS frequency (optional connection).
• An adjustable dimming regulator is included to provide dimmed voltage to an external annunciation (750ma max).

Two versions of the MD41-24P( ) series relay units are available:

• MD41-24P(14), 24 pole relay for 14 volt operation.
• MD41-24P(28), 24 pole relay for 28 volt operation.