KING KMA 20 User manual

KING
KMA
20/KR21
MARKER
BEACONRECEIVER
ISOLATIONAMPLIFIER
INSTALLATION
MANUAL
006-0044-02
REV. 2JUNE, 1976

KlNG
KMA 20 /KR 21
MARKER BEACON RECEIVER/
ISOLATION AMPLIFIER
TABLE
OFCONTENTS
SECTION
IGENERALINFORMATION
Paragraph Page
1. 1 Introduction 1-1
1. 2Technical Characteristics 1-2
1. 3Accessories Required 1-6
SECTION
II INSTALLATION
2. 1General 2-1
2.2 Unpacking and Inspecting Equipment 2-1
2. 3Installation Notes and Precautions 2-1
2.4 Installation Procedure 2-2
2. 5Marker Antenna Installation 2-2
2. 6KA 40 Installation (Optional) 2-3
SECTION
IIIOPERATION
3. 1 Marker Beacon (KMA 20 and KR 21) 3-1
3.2 Isolation Amplifier (KMA 20) 3-2
LISTOFILLUSTRATIONS
Figure Page
2-1 KMA 20 Installation Drawing 2-4
2-2 KR 21 Instanation Drawing 2-5
2-3 KA 40 Instanation Drawing 2-6
2-4 KMA 20 Interconnect Diagram 2-7
2-5 KR 21 Interconnect Diagram (27. BV DC') 2-9
2-6 KR 21 lnterconnect Diagram (13. 75VD(') 2-9
2-7 KA 40 lnterconnect Diagram 2-10
2-8 Pin Function for 000-1024-00 thru -16 2-11
i

KING
KMA 20/KR 21
MARKER BEACON RECEIVER/
ISOIATION AMPLIFIER
HISTORY
OFREVISIONS
Hevision 1, August 1972
Page Reason for Change
Title Page Denotes New Revision
Warranty New Warranty
Contents Table of Contents Added
History of Rev. History Revision Added
1-1 Lamp Test Information Added
1-3 Sensitivity and Selectivity Revised
1-4 Word Misspelled
1-6 Installation Parts List Added
2-1 Warning Note Added
2-2 Paragraph 6 Changed to 7. New Paragraph 6 added.
2-3 Figure Numbers corrected
2-4 New Installation Drawing
2-5 New Installation Drawing
2-6 Drawing Turned on Page
2-7 Interconnect Corrected
2-11 Pins Reversed
2-13 Figure Added
2-15 Figure Added
3-1 Marker Dese ription Changed
3-1 Information Added about HI-LO Switch
3-2 09/11 Information Added
ii

KMA20/KR 21
MARKERBEACON
RECEIVER/
ISOLATIONAMPLIFIER
HISTORY
OFREVISIONS
Revision 2, June, 1976
Page Reasons for Change
Title Page Denotes New Revision
Warranty Deleted
Contents Page Number changes
History of Revision Added for Revision 2
1-3 Technical Characteristics Updated
2-2 Paragraph 2.3 (5) updated
Paragraph 2.3 (7) updated
2-7 Interconnect updated
2-9 Figure 2-6A changed to 2-5
Figure 2-6B changed to 2-6
2-11 Figure 2-8 updated
3-2 Section 3.2 updated
iii

KING
KMA 20/KR 21
MARKER BEACON RECEIVER/
ISOLATION AMPLIFIER
SECTION
I
GENERAL
INFORMATION
1.1 INTRODUCTION
The King KMA 20 is a compact transistorized unit providing the functions of marker
beacon receiver, isolation amplifier and audio control panel. The unit has been styled
to harmonize with the all new generation of Silver Crown panel mounted equipment.
TSO certification of the KMA 20 assures operation under varying environmental
conditions.
The KMA 20 is designed to provide auniformly functioning aircraft radio system when
utilized with other units of the new Silver Crown line. Although the equipment is designed
primarily for use with the KX 170 NAV/COMM unit, it will also perform effeciently with
older Silver Crown transceivers and radios.
Significant new features of the KMA 20 design include its AUTO switch feature: semi-
concealed marker light presentation and its ability to control COMM and NAV audio
independently. Automatic dimming circuitry for the marker lamps, to compensate for
ambient cockpit lighting, is also incorporated in the design.
Within the KMA 20, the marker beacon receiver comprises one section of the unit.
The marker receiver of the KMA 20, available without the isolation amplifier and audio
panel is the KR 21. The receiver is a crystal controlled superheterodyne receiver and
has excellent selectivity and freedom from interference of television and FM stations.
Operating controls for the marker receiver consists of two toggle switches on the KMA
20: a HI-LO sensitivity and lamp test control and an audio selector switch. The KR 21
has only the HI-LO sensitivity and lamp test control. A three light presentation is de
signed into the front panel of the unit with colored lenses to indicate passage over the
markers. Besides the colors, the stations are identified by the letters A-O-M engraved
on the lenses plus the appropriate frequency audio tone. Should the aircraft user desire a
aremote location for the marker lights, King Radio Corporation manufacturers an
optional remote light assembly designated the KA 40 for use with the KMA 20 only.
The isolation amplifier of the KMA 20 makes possible the combining of all receiver
audio inputs into a single cockpit speaker with 40db of isolation between each radio. The
input power levels of the signals are amplified to the level necessary to drive a 4 ohm
speaker. An electronic muting circuit (diode switch) is provided to automatically isolate
the output of all receivers from the isolation amplifier whenever the microphone button
Rev. 1, August, 1972 Page 1-1

KING
KMA 20/KR 21
MARKER BEACON RECËIVER/
ISOLATION AMPLIFIER
is pressed. This feature eliminates the possiblity of audio feedback in the cockpit. The
amplifier design utilizes only one integrated circuit and a push-pull output stage for
high reliability.
Audio control functions of the Silver Crown radio system are performed at the front
panel of the KMA 20. A microphone selector rotary switch, aseries of eight audio
selector switches and a marker beacon receiver sensitivity control are the operating
controls of the unit. The microphone selector routes audio and keying information to
the selected transceiver or to a EXT ramp hail speaker or passenger address system.
The AUTO switch control of the standard model is utilized in conjunction with the micro-
phone selector switch. For normal operation of the AUTO switch, COMM 1 and COMM
2are placed in the center (off) position. With the AUTO switch in the SPEAKER position,
the receiver audio selected is automatically controlled by the operation of the micro-
phone selector. Thus if transmitting on COMM 1, receiver audio for COMM 1will be
routed to the cockpit speaker. This feature eliminates the constant manipulation of
COMM receiver audio selectors when switching back and forth between transmitters.
Speaker, off or mute, and headphone audio control of each of the aircraft radios is
accomplished with the remaining three-position toggle switches.
Aseries type solid state regulator is used to supply the regulated voltage to the marker
receiver and audio boards of the unit. Since each aircraft installation is wired for eithier
13. 75 or 27. 5V operation of the unit, the KMA 20 and KR 21 are completely interchange-
able between aircraft with no internal wiring changes.
1.2 TECHNICALCHARACTERISTICS
MARKER BEACON RECEIVER -KMA 20/KR 21
SPECIFICATION CHARACTERISTIC
TSO COMPLIANCE: TSO C35c Env. Category DACAAAX.
CONTROL: Panel mounted equipment. Sensitivity and
audio selector controls on the front panel of
the unit.
DUTY CYCLE: Continuous.
INPUT IMPEDANCE: Designed to match 50 ohm antenna.
OUTPUT: Capable of 10 milliwatts into Isolation Amp-
lifier input of 5000. Capable of 6. 25 watts at
the 4O speaker output.
Page 1-2 November, 1969

KING
KMA 20/KR 21
MARKER BEACON RECEIVER/
ISOLATION AMPLIFIER
SPECIFICATION CHARACTERISTIC
OUTPUT: (Cont) Factory adjusted to 1. OVRMS at the isolation
amplifier input.
DESIGN: All solid state. No moving parts.
FREQUENCY: Crystal-controlled at 75MHz.
SENSITIVITY: Low: 2, 000µv hard for lamp threshold
High: 500µv hard for lamp threshold
SELECTIVITY: 6db at ±10KHz Min.
60db at 575KHz Max.
AGC CHARACTERISTICS: Less than 6db variation in audio output level
when the rf level is varied from lamp thresh-
old to 200, 000µv.
ISOLATION AMPLIFIER -KMA 20
TSO COMPLIANCE: TSO C50b Env. Category DACAAAX.
CONTROL: Panel mounted equipment. All operating
controls are on the front panel of the unit.
DUTY CYCLE: Continuous.
INPUTS: Standard model accomodates two transceivers
and four external receivers, International
model accomodates three transceivers and
four external receivers.
INPUT IMPEDANCE: 500 ohms.
INPUT ISOLATION: 40db between input channels.
INPUT SELECTOR SWITCHES: Each isolated audio input has three independent
terminations: SPEAKER, OFF or PHONE.
INPUT MUTING: Audio Muting is 40db or better when a trans-
mitter is keyed.
Rev. 2, June, 1076 Page 1-3

KING
KMA 20/KR 21
MARKER BEACON RECEIVER/
ISOLATION AMPLIFIER
SPECIFICATION CHARACTERISTIC
SPEAKER OUTPUT: 4ohm output:
Rated power output is 6. 25 watts at the 4ohms
speaker output. With a supply voltage of
27. Svde, output power capability increases
to 8watts.
8ohm output:
Rated power output is 6, 25 watts at the 8ohm
speaker output. With a supply voltage at 27. 5
vde, output power capability increases to
8watts.
DISTORTION: Less than 10a/o at rated output.
FREQUENCY RESPONSE: .Within 6dh from 350Hz to 3000Hz.
KMA 20 GENERAL
POWER REQUIREMENTS:
lnstrument panel lighting: 13. 75V 27. 5V
KMA 20 idle current: 300ma 150ma
KMA 20 operating current: 1. 1amps 1. 1amps
PHYSICAL DIMENSIONS: Length: 6. 293 inches behind instrument panel.
Width: 6. 2 inches.
Height: 1. 6 inches.
WEIGHT: 2. 3 lbs.
KR 21 GENERAL
POWER REQUIREMENTS:
Idle Current: 170ma at 13. 75V
120ma at 27. 5V
Operating Current: 300ma at 13. 25V
250ma at 27. 5V
Panel Lighting: None
Page 1-4 Rev. 1, August, 1972

KING
KMA 20/101 21
MAR<ER BEACON REC,EIVER/
I3OLATION AMPLIFIER
SPE CIFICATION CHARACTERISTIC
PHYSICAL DIMENSIONS: Length: 5. 667 inches
Width: 3. 20 inches
Height: 1. 050 inches
WEIGHT: 0. 562 lbs.
KA 40 GENERAL
POWER REQUIREMENTS: Marker lamp power furnished by KMA 20
0. 125 amp while the lamp is operating.
PHYSICAL DIMENSIONS: Length: 2. 5inches (including connector)
Width: 3. 2 inches
Height: 1. 05 inches
WEIGHT: 0. 25 lbs.
November, 1969 Page 1-5

KMA20/KR 21
MARKERBEACONRECEIVER/
ISOLATION AMPLIFIER
1.3 UNITS/ACCESSORIES REQUIRED
A. Unit: KMA 20 KPN 066-1024-XX (See Figure 2-8)
KR 21 KPN 066-1021-01
B. KMA 20 Installation Kit: KPN 050-1167-00
KR 21 & KA40 Installation Kit: 030-2016-00 Connector and
089-6163-05 (4) screws
Both are included with unit.
Installation Kit 050-1167-00 consists of the,following:
QUANTITY DESCRIPTION KING PARTNO.
1Solder Lug (Dual) 008-0041-00
2Cable Half Clamp 030-1019-00
132 Pin Connector
Ampheno1 26-190-32 030-2061-01
1Mounting Plate Cover 047-1760-00
1Mounting Plate Connector 047-1762-01
2#4 Esna Nut 089-2188-22
2Flathead 4-40 x5/16 Screw 089-5523-05
4Pan Head 4-40 x1/4 Screw 089-5903-04
2Pan Head 6-32 x 1/4 Screw 089-5907-04
2Pan Head 4-40 x5/16 Screw 089-5903-05
2Flat Washer 089-8025-30
Accessories:
KA 40 Remote Lamp Assembly (071-0003-00)
Page 1-6 Rev. 2, June, 1976