Honeywell KMA28 Swap Mode, Backlighting, Unswitched inputs, Intercom wiring, Entertainment Input

Bendix/King

KMA28

Audio Amplifier/Intercom/Marker Beacon Receiver

2.4.7 "Swap" Mode

When a momentary, normally open, push-button switch is connected between pin 10 on the top connector and aircraft ground, the user can switch between Com 1 and 2 by de- pressing this switch without having to turn the mic selector switch. This yoke-mounted switch eliminates the need to remove your hands from the yoke to change transceivers.

2.4.8 Backlighting

The KMA 28 has an automatic dimming of the pushbutton annunciator LEDs and marker lamps controlled by a photocell. Control of the unit backlighting is through the aircraft avionics dimmer. Connect the dimmer control line to J1 pin D for 14 volt systems, and to J1 pin F for 28 volt systems. Pin E is light ground.

If an external dimmer control is not used, a constant low level back light illumination can be established for nighttime viewing. Pin D or F (depending on system voltage) must be tied to power (J1, pin 20) for the back lighting system to work. The photocell mounted in the unit face will automatically adjust the intensity of the push-button annunciator LEDs.

2.4.9 Unswitched inputs

J1, pin T is the unswitched input number 1 and J1 pin 17 is unswitched input 2. These inputs are presented to the pilot and copilot regardless of the audio configuration, and will always mute the entertainment inputs. These 510Ω inputs can be used for altimeter DH audio, GPS waypoint audio, autopilot disconnect tones, air-to-ground (Flitefone) tele- phone ringer or any other critical audio signal. This input is not related to the cellular telephone interface.

2.4.10 Intercom wiring

The top connector (J2) is for the intercom and additional functions. See Appendix for in- tercom connection configurations. It is critical to the proper operation of this system to have this connector wiring made in accordance with these diagrams. Use 2- and 3- conductor, MIL-spec cable as shown. Connect the shields at the audio panel end only, and tie to the audio low inputs as shown.

2.4.10.1Entertainment Input

NOTE: Use the low level output of any entertainment device to connect to the audio panel. Maximum signal level is 1 VAC p-p.

DO NOT use a speaker-level output, this will cause internal damage in the audio panel

2.4.10.1.1 Stereo entertainment

Two stereo entertainment devices (CD player, cassette player, etc.) can be connected to the unit. Install two 1/8-inch stereo jacks in a convenient location so that the pilot can plug

006-10565-0000 Page 2-4 Rev. 0, Sept. 2000