KING KR 21 - SECTION I GENERAL INFORMATION; 1.1 INTRODUCTION

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
a
uniformly 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
a
remote
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