HONEYWELL BENDIX KING® TSO'd KMA 24 & KMA 24H Silver Crown Audio Panels ae probably ones of the most common audio panels found in aircraft. They are TSO'd compact, self contained, fully solid-state pushbutton audio selector panels with speaker and headphone isolation amplifiers, and a marker beacon receiver (KMA 24) or intercom (KMA 24H). Depending on selected model, KMA 24 & KMA24H systems offer different features and combinations of marker light presentation, AUTO, 2 COMMs, 2 NAVs, DME, ADF, HF, TEL selections.
The KMA 24 & KMA24H Audio Panels are DISCONTINUED although some NEW units may be available under special order or while stocks exist, they are mostly offered for outright sale or in exchange / trade-ins (*) for returned customer owned units in USED (Serviceable or Overhauled) Conditions (**) and accompanied by the relevant certification (e.g. yellow tag, 8130-3 form). The letters "SV","OH" and "EX" in the product reference numbers (SKU) indicate the condition/sale terms. Racks & connectors (for new installations) are sold separately. BENDIX KING® KMA 24 & KMA24H Audio Panels are sold on demand. Require backordering. Delivery time cannot be specified. For additional information please contact us.
BENDIX KING® KMA 24 & KMA 24H Audio Panels' Product Features:
- compact size, only 1.3 inches high in the aircraft avionics stack. Can be installed in the top slot of the instrument panel
- styled to match with the other BENDIX KING® Silver Crown units but can be integrated into any 500 ohm output audio system
- push button audio selector panel ensuring complete, flexible audio control
- control of as many as 3 transceivers and 6 receivers, including the internal marker beacon receiver and its automatically dimmed 3-light indicator (KMA 24 )
- control of up to 5 transceivers and 5 receivers, or 4 transceivers and 6 receivers (KMA 24H). In the KMA 24H the internal marker beacon receiver has been replaced with an intercom providing unprecedented flexibility. The intercom features capability for hot mike, voice activation (VOX), or keyed activation of up to five intercom stations. In hot mike operation all intercom microphones remain active at all times whether the operator is talking on intercom or not. Voice activated operation has the microphone active only when the operator begins to talk. In keyed operation, the operator may depress a separate intercom switch to activate the microphone for intercom usage.
- two unswitched inputs for use as altimeter warning and telephone ringer
- outputs for ramp hailer and passenger address or intercom
- separate isolation amplifiers are provided for headphones and speaker to provide isolation even when the same source is selected
- three isolated 16 ohm resistors provided for transceiver speaker output loads
BENDIX KING® KMA 24 Audio Panel features two rows of buttons, with marker beacon lights on the left by and a rotary knob on the right allowing the user to select COM 1 or COM 2. The top row of buttons directs the selected audio output to the speaker in the aircraft. The bottom row of buttons directs the selected audio output to pilot headset.
Marker beacon lights, used in many ILS instrument approaches include the outer marker (blue light marked “O”), the middle marker (amber light marked “M”) and the inner/airway marker (white light marked “A”). Marker beacons emit a 75-Mhz carrier frequency signal. Marker beacon lights illuminate when the aircraft passes over the respective marker together with audible signals either through the speaker or the pilot's headset as selected by the latter.
TST button is used to test the marker beacon lights. Pressing this button causes all the marker beacon lamps to illuminate. The TST button should not be pushed when the autopilot is coupled on an ILS approach. Some autopilots, including Bendix King models, use the marker beacons to change the sensitivity of the autopilot.
SENS button just to the right of the amber marker beacon lamp selects the sensitivity of the marker beacons. HI allows the marker beacon signal to be detected approximately one mile before passing over the beacon.
Next to the “O” marker beacon lamp is a photoelectric cell which controls the brightness of the marker beacon lamps.
TEL button controls audio for a radio telephone. In some KMA 24 audio panels the TEL function has been replaced by HF, for operation with a high frequency transceiver. Either TEL or HF function must also be selected on the rotary knob on the right side of the audio panel.
COM 1 and COM 2 buttons control audio received from the respective communication radios. The top row button directs output to the aircraft speaker, and the bottom row button directs it to the pilot headset.
NAV 1 and NAV 2 buttons controls the audio received from the respective NAV radios. This includes any weather information, such as HIWAS as well as the Morse code IDENT. Many NAV radios have a switch on the radio for IDENT. This must be selected in addition to selecting either speaker or headset for the audio.
DME button allows listening to the Morse code identifier for any DME that is co-located with VOR or localizer ground stations. Most DME receivers have the ability to enter a frequency separately from the NAV radios. However the most common method of operation is to remote the DME receiver to either NAV 1 or NAV 2.
MKR button allows the pilot to hear the marker beacon audio signals while the ADF button enables listening the Morse code identifier of an NDB station. As a good practice this button should be ON during the entire of an NDB approach to verify integrity of the signal. Unlike VOR receivers, ADF receivers do not display an OFF flag, so the Morse code is the only way to ensure the data being received by the ADF receiver is valid.
The rotary switch on the right side of the KMA 24 Audio Panel controls the transmission frequency.
For KMA 24 models equipped with the “AUTO”receiver audio select feature, pilots can automatically slave the received audio information to whichever frequency they have selected with the rotary switch. The transmitter selected with the microphone selector switch will be matched automatically with the appropriate COM receiver audio on either headphone or speaker, or both, by simply pressing the desired headphone and/or speaker “AUTO” push button. AUTO button causes sometimes confusion for first time users of an Audio Panel. COM 1 and COM 2 push buttons should be disengaged unless it is desired to additionally listen to a COM receiver other than the one selected with the microphone selector switch although it can be confusing to try to listen to two frequencies at the same time.. With “AUTO” function activated the pilot may change the rotary microphone switch back and forth, as needed, without having to reselect the corresponding COM, TEL, or HF receiver buttons in order to listen to the receiver.
For models equipped with an intercom the INT position of the rotary switch selects cabin intercom. This allows the crew to address the passengers over the cabin speaker while setting the switch at the EXT position allows the crew to address people on the ramp through an external ramp hailer speaker, if one is installed.
The rotary switch on the right side of the KMA 24 can be set for either COM 1 or COM 2. The rotary switch on the right side of the Audio Panel controls the transmission frequency. By pressing the AUTO button in the bottom row (headset), they will automatically hear the transmissions from either COM 1 or COM 2, depending on which one has been selected by the rotary switch. So with AUTO selected, pilots may switch back and forth between COM 1 and COM 2 with the rotary switch without having to reselect COM 1 or COM 2 using the push buttons. If they desire to hear audio from the other COM radio, they may do so by simply pressing the appropriate button for either speaker or headset
BENDIX KING® KMA 24 & KMA 24H Audio Panels' Product Specifications:
TSO Compliance:
Marker Beacon Receiver: TSO C35d, Class A
KMA24—Env. Cat. A1D1/A/PKS/ XXXXXXZBAAA
Audio Amplifier: TSO C50b
KMA 24H—Env. Cat. A2D1/A/KPS/ XXXXXXB/AB/BZ/A
Weight: 1.7 lb. (0.77kg)
Physical Dimensions: Length behind panel: 6.8 in. (17.30 cm), Width: 6.25 in. (15.88 cm), Height: 1.3 in. (3.30 cm)
Duty Cycle: Continuous
Power Requirements (not including instruments lights): KMA 24 13.75v 27.5v, Idle current, mike switch on 110 ma 170 ma, Idle current, mike Less than Less than switch off 8 ma 16 ma, Max. operating current 1.9 a 1.9 a, KMA 24H Idle current 350 ma 500 ma, Max. operating current 1.8 a 1.8 a
Temperature Range: -20ºC to +55º with brief operation at +70ºC (KMA 24), -20ºC to +70ºC continuous (KMA 24H)
KMA 24 Input Impedance: 500 ohms
KMA 24H Input Impedance: 320 ohms
KMA 24: 40 db between inputs
KMA 24H: 60 db between inputs
Speaker Output:
With 13.75v Supply:
Into 4 ohm load: 7 w (KMA 24)
6 w (KMA 24H)
Into 8 ohm load: 4 w
Into 8 ohm load from
8 ohm tap: 6 w (KMA 24H)
With 27.5v Supply:
Into 4 ohm load: 12 w (KMA 24)
10 w (KMA 24H)
Into 8 ohm load: 6.5 w
Into 8 ohm load
from 8 ohm tap: 10 w (KMA 24H)
Output Characteristics:
Distortion: Less than 5 percent at rated output
Frequency response:
KMA 24: Within 6 db from 350 hz to 6,000 hz
KMA 24H: Within 3 db from 350 hz to 6,000 hz
(*) In the case of an exchange/trade-in option of a customer unit, the full selling price of the ordered unit is charged and the core credit is refunded or credited towards future orders when our co-operating supplier verifies that the unit is in a reasonable, repairable condition. It is recommended that this option is selected by our customers mainly for upgrades and only in cases when their units are functioning properly at the time removal from the aircraft. In cases when customer units are found by our supplier to be non-repairable, the core deposit shall not be refunded and shipping charges shall apply if customers wish the return of these units to them.
(**) As per FAA requirements, Serviceable Condition means that the units have been repaired as needed and tested according to the manufacturer's procedure to meet the manufacturer's performance specifications. They are legally approved for installation and use (return to service). In this condition, the unit is NOT disassembled unless problems and/or repair needs are detected during testing. In Overhaul Condition, the units have been tested to determine any problems, disassembled, inspected, cleaned and repaired as necessary, reassembled, tested and aligned as required by the manufacturer manual and finally certified that they meet manufacturer’s specifications.
