AirPlus KRT2 Guide

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
DE-3000-800100e
KRT2 & KRT 2A
Revision 5.0
Software >5.00
- 1 - of 46
KRT2
VHF Communication
Transceiver
P/N 100-( )-( )
Operation and Installation
Manual

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
DE-3000-800100e
KRT2 & KRT 2A
Revision 5.0
Software >5.00
2 of 46
Record of Revisions
Revision Date Subject
1 06 Juni 2010
Erstausgabe
2 20 Sep 2010
Revision Stecker / Redaktionelle Änderungen
3 05 Feb 2011
Editorial update
4 04 Mai 2012 Cable-harness correction
5 16 Mai 2012 Software advantage for battery indication,
error reports
List of Service-Bulletins (SB)
Service-Bulletins have to be inserted in the manual, and entered in
the table.
SB Number
Rev.
No.
Date
Issued
Date
Inserted
Name
Unit overview
Item No. Product Overview
Basic Version
Introduction of::
• 2 Standard Microphone Inputs
• Auxiliary Audio Input
• DUAL Watch Function

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
DE-3000-800100e
KRT2 & KRT 2A
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TABLE OF CONTENTS
1. GENERAL ...........................................................................................................................5
1.1. Symbols ............................................................................................................................ 5
1.2. Abbreviations.................................................................................................................... 6
1.3. Customer Service.............................................................................................................. 7
1.4. KRT2 Transceiver properties ........................................................................................... 7
2. CONTROL general.............................................................................................................8
2.1. Control Elements Overview ............................................................................................. 8
2.2. Display............................................................................................................................ 10
3. OPERATION .....................................................................................................................12
3.1. General............................................................................................................................ 12
3.2. ON / OFF Switching....................................................................................................... 12
3.3. Frequency Selection ....................................................................................................... 12
3.3.1. Direct Frequency Selection ..................................................................................... 13
3.3.2. Frequency Selection from the Favourites List ........................................................ 13
3.3.3. Storing and Editing Favourites................................................................................ 14
3.4. AUD – Audio Menu ....................................................................................................... 16
3.4.1. VOL – Volume........................................................................................................ 16
3.4.2. SQ -- Squelch .......................................................................................................... 16
3.4.3. VOX – Intercom Voice Trigger Level Setting........................................................ 17
3.4.4. TXm – PTT Switch Selection ................................................................................. 17
3.4.5. INT – Intercom Volume .......................................................................................... 18
3.4.6. EXT – External Audio Input Volume ..................................................................... 18
3.4.7. DIM – Display Brightness (Batt.-voltage) .............................................................. 18
3.4.8. CON – Display Contrast.......................................................................................... 18
3.4.9. SIT – Side tone ........................................................................................................ 18
3.4.10. MIC – Setup......................................................................................................... 19
3.5. DUAL Watch.................................................................................................................. 21
3.6. Transmitter Operation..................................................................................................... 23
3.7. Self test monitor.............................................................................................................. 24
3.7.1. Optical side tone...................................................................................................... 24
3.8. Resetting to factory settings ........................................................................................... 25
3.9. SET UP - Menu .............................................................................................................. 26
3.9.1. ERASE – Erasing the Favourites List ..................................................................... 26
3.9.2. Channel Spacing...................................................................................................... 27
4. Remote Control .................................................................................................................27
5. Installation .........................................................................................................................28
5.1. Installation Hints............................................................................................................. 28
5.2. Telecommunication Data................................................................................................ 28
5.3. Scope of delivery............................................................................................................ 28
5.4. Unpacking and Inspecting the Equipment...................................................................... 29
5.5. Mounting ........................................................................................................................ 29
5.6. Electrical Connections.................................................................................................... 30
5.6.1. Microphone-Connection.......................................................................................... 30
5.6.2. Earphone Connection .............................................................................................. 31

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
DE-3000-800100e
KRT2 & KRT 2A
Revision 5.0
Software >5.00
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5.6.3. External Audio Input............................................................................................... 31
5.7. Finally Audio-Setup ....................................................................................................... 32
5.7.1. For gliders ............................................................................................................... 32
5.7.2. For motor gliders..................................................................................................... 32
5.7.3. Für Motor planes ..................................................................................................... 32
5.8. Wiring............................................................................................................................. 33
5.8.1. Wire Gauges............................................................................................................ 33
5.8.2. Connector Pin-Configuration .................................................................................. 33
5.8.3. Wiring Diagram....................................................................................................... 34
5.8.4. Connection support ................................................................................................. 36
5.9. Antenna........................................................................................................................... 37
5.9.1. Antenna Selection ................................................................................................... 37
5.9.2. Installation Recommendation.................................................................................. 37
5.10. Microphone general .................................................................................................... 38
5.11. Post-Installation Check ............................................................................................... 38
5.12. Starting Up .................................................................................................................. 39
5.13. Accessories ................................................................................................................. 39
5.14. Drawings ..................................................................................................................... 41
5.14.1. Dimensions .......................................................................................................... 41
5.14.2. Installation Directions.......................................................................................... 42
6. ANNEX..............................................................................................................................43
6.1. Frequency / Channel- schedule....................................................................................... 43
6.2. Technical Data ................................................................................................................ 44

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
DE-3000-800100e
KRT2 & KRT 2A
Revision 5.0
Software >5.00
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1. GENERAL
This manual contains information about the physical, mechanical and
electrical properties as well as a description for the operation and
installation of the VHF airborne transceiver KRT2.
1.1. Symbols
WARNING
Non compliance may cause personnel injury due to
radiation or fire.
CAUTION
Non-compliance may cause damage or incorrect operation
of the transceiver.
INFORMATION

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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1.2. Abbreviations
Abb
Description
Definition
PTT Push to Talk Transmitter activation
VOX
Voice operated intercom Voice level setting fort he activation
of the intercom
INT Intercom level Intercom volume level setting
SQ Squelch Squelch setting
DIM Dimming Display brightness setting
CON
Contrast Display contrast setting
EXT External audio input External Audio input level setting

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
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KRT2 & KRT 2A
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1.3. Customer Service
In order to process returned units most expeditiously, please fill in the
form xxxxxxxxxxxxxxxxxxx to be found under AIRplus Service at
www.airplus24.com.
Suggestions which will improve this manual are very
much appreciated at: www.airplus24.com
Information concerning software updates are available
under AIRplus Avionics at www.airplus24.com
1.4. KRT2 Transceiver properties
• VHF airborne transceiver
• Frequency range 118,000 to 136,975 MHz
• Channel spacing 8,33/25 kHz (2278 channel)
• Fast channel selection
• 4 separate microphone inputs (2 x standard or 2 x dynamics)
• Audio-input for other audio devices
• Installation: Standard panel cut-out (57 mm)
• 100 user definable frequencies with up to 8 character
designators
Continuous transmissions will be turned off after 2 minutes.
(Stuck mic function).

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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2. CONTROL general
2.1. Control Elements Overview

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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ON / OFF Self-locking switch
DUAL
WATCH
1. Scanning between the Active and
Standby frequencies
2. Positioning cursor to the left when
programming the station designator
AUDIO
SELECT
1. Stepping through the audio menus
VOL SQ VOX TX INT EXT DIM CON
SIT and MIC
2. Positioning cursor to the right when
programming the station designator
FAVOURITES
1. Frequency and designator selection
from the favourites list
2. Programming of favourites (frequency
and designator)
EXCHANGE
Exchange
of the
Active and Standby
frequencies
FREQUENCY
1. Selection of the frequency range
MHz, 100kHz, 10kHz
2. Toggles between frequency and
designator when programming the
favourites
TURNING
KNOB
Sets all variable values in any menu
1. Volume setting of headsets and
speakers
2. MHz/kHz selection of the standby
frequency in 3 different ranges
3. Favourite selection
4. Alpha character selection when
programming favourites
5. Change of microphone settings

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VHF- Communication Transceiver
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KRT2 & KRT 2A
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2.2. Display
Indication Meaning Remarks
RX Reception RX is displayed during
reception with a squelch
value of 02 or more
TX Transmission Transmitter operates
normally
Te Transmitter was turned off
automatically after 2 min
continuous operation
125.100 Active frequency
KIEL Active frequency station
designator
Displayed when frequency
and designator is stored in
the favourite list
VOL …… Receiver volume level
(default after a certain time
delay)
When AUD was pressed
the corresponding Audio
Menu item and setting is
displayed
SQ Squelch
VOX Voice operated intercom
DIM Display brightness
CON Display contrast
INT Intercom - Volume
EXT Volume of external devices
TX** PTT button selection Left/Right/Both
SIDE Side tone During transmitter operation
BREMEN Stand
by frequency station
designator
Displayed when frequency
and designator is stored in
the favourite list

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
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KRT2 & KRT 2A
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Display Meaning Remark
DUAL Active frequency AND
Standby Frequency are
monitored simultaneously
DUAL function is
deactivated by frequency
change or by pressing the
DUAL button again
[03]
(MEMORY)
Favourite list index
(0-99)
When frequency and
designator are stored at
this index they are
displayed
125.100 upper Active - frequency
134.825 lower
Standby - frequency
< The pointer indicates what
the turning knob will change
VOL SQ VOX…..etc
Standby frequency
Arrow is positioned in
correspondence to the
button pressed
( AUD or FREQ)
BAT Supply voltage is low
<10,5V
Battery low or
Battery/Generator faulty
Er_ANT Antenna error Bad antenna match
a v e Status of certain Audio
menu functions
a = AUX. Input active
v = VOX active
e = external Intercom
switch active
Er_PLL Internal error, no transmission Return the transceiver for
maintenance
Er_ADC Internal error, Return the transceiver for
maintenance
Er_FPA Internal error; unit not usable Return the transceiver for
maintenance
Er_I2C Internal error; unit not usable Return the transceiver for
maintenance
Er_si53 Internal error; unit not usable Return the transceiver for
maintenance
Er_D10 Internal error; reception corrupt Return the transceiver for
maintenance
Key_Block Internal error; unit not usable Return the transceiver for
maintenance

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
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KRT2 & KRT 2A
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3. OPERATION
3.1. General
There is a normal operating mode in which the turning knob always is
connected to the volume (VOL). The normal operating mode can be left by
pressing the AUD, FREQ or MEMORY button.
When not in the normal mode and there is no pilot action for more than 10
seconds the unit returns to the normal mode.
3.2. ON / OFF Switching
ON / OFF switching is achieved with a self-locking switch.
After power up the following display will show up:
Device-name
KRT2
Software-
Version e.g. V2.0
Gerätename
KRT2
Software-
Version e.g. V2.0
(example)
The unit then starts in the normal operating mode using and displaying the
data last used.
3.3. Frequency Selection
There are two different frequency selection methods:
• Direct Input

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
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KRT2 & KRT 2A
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• Selection from the favourite list (index 0-99)
3.3.1. Direct Frequency Selection
The Standby-Frequency is set with the
tuning knob in 3 different ranges. The
selected range is highlighted and can
be changed with the FREQ button.
Frequency ranges are: 1xx.nnn
1nn.xnn
1nn.nxx
Press the FREQ button once or
several times until the desired
frequency range is highlighted.
When the pointer is not next to the
Standby Frequency window, it will be
repositioned with the first pressing of
the FREQ button.
Exchanges the Active and
Standby frequencies.
When the Exchange button was not pressed, the Standby frequency
display will return to its normal appearance after 20 seconds.
3.3.2. Frequency Selection from the Favourites List
By pressing and operating the turning knob a specific favourite list
position can be accessed [xx] (xx = index 0 … 99). When frequency and
station designator have been defined, they will be displayed in the Standby
and station designator windows.
The favourite list designators can be sorted in alphabetic order (see 3.3.3).

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
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KRT2 & KRT 2A
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Exchanges the Active and Standby frequencies.
The selection procedure can be terminated with either the AUD or FREQ
buttons. Without pressing any of these buttons the unit will return to its
normal operating mode after 20 seconds.
3.3.3. Storing and Editing Favourites
Any displayed Standby Frequency can be given a designator and both can
be stored together as favourites in the favourite list. Both, the frequency
and designator of a favourite can be edited.
First press button and by means oft he turning knob go to the
desired favourite list position which may be empty or the favourite to be
edited (index [00 …99]).
Press the MEMORY button a second time and „–EDIT--„ will show up in the
program window.
In the designator window a
blinking cursor will show up
under the most left character.
The turning knob selects the
desired character.
The AUD button positions the
curser one character to the
right. The DUAL button
positions the cursor one
character to the left and
simultaneously erases this
character.
The station designator can consist of maximum 8 characters.
Press the FREQ button and follow the normal direct input procedure to edit
the frequency.
Press the MEMORY button in order to go to the station designator window

User & Installation manual
VHF- Communication Transceiver
Doc.-Nr:
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KRT2 & KRT 2A
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for editing he designator if required
.
Pressing MEMORY again terminates editing and SAVE? will show up.
SAVE? is available for 20 seconds and must be acknowledged by the
button. No acknowledgement within 20 seconds results in the termination of
the storing procedure.
When the button was pressed SORT? will show up.
SORT? is available for 20 seconds and must be acknowledged by .
When sorting was acknowledged with the button, all 99 favourites will
sorted in alphabetical order which can take several minutes.
During the sort procedure „RUN nn“ is displayed in the program window,
with nn being the running index.
When the MEMORY button is pressed during the time when SORT? is
displayed the sorting procedure will not start and storing and editing is
terminated. The transceiver then resumes the normal operating mode.
When the MEMORY button is pressed during the time when „RUN-nn“ is
displayed the sorting procedure is terminated. The favourite list then is
sorted partially only and the transceiver resumes the normal operating
mode.
Further favourites can be stored or edited by following the normal input
procedure.
For time saving purposes it is recommended to initiate the sorting
procedure after the last favourite has been saved or edited.

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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3.4. AUD – Audio Menu
Any action in the Audio Menu
requires the pointer (<) to be next
to the Audio menu window (see
picture). When the pointer is next
to the Standby frequency window,
the pointer can be repositioned by
pressing the AUD button once.
VOLnn is the Audio menu default
display. No action on any control for
more than 10 seconds will result in
the VOLnn display.
Audio Menu items can be accessed in the following order by repeatedly
pressing the AUD button.
VOL (default) SQ VOX TXm** INT EXT DIM CON SIT MIC
Audio menu items to right of the above list are more seldomly used than
the left ones.
3.4.1. VOL – Volume
Turning the turning knob changes the receiver volume.
VOLnn Range: 01 - 16
Die VOL setting only concerns the receiver and not the
intercom system. Intercom volume values are set in the INT
audio menu.
.
3.4.2. SQ -- Squelch
Pressing the AUD button once enables the turning knob to change the
squelch level values.
SQnn Value range: 01 – 10

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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The Squelch setting is depending on several factors.
For engine driven airplanes an initial setting of 05-08 is recommended.
Gliders may need a lower setting. The lower the Squelch level value the
higher is the input sensitivity. A high sensitivity setting is susceptible to
noise from other sources like ignition strobe-lights etc.
Standard SQ-level is 05 ... 08. Higher setting may
suppress strong input signals. Squelch does not influence
the intercom system.
3.4.3. VOX – Intercom Voice Trigger Level Setting
Pressing the AUD button twice enables the turning knob to change the voice
level which triggers the intercom.
The intercom voice trigger level must be set to such a value which
prevents that normal cockpit noise can be heard in the earphones. The
intercom system shall only be activated when talking at a normal
voice level into the microphone.
The higher the trigger level the louder the voice must be in order to
trigger the intercom system.
VOX on condition is indicated by flag “v”.
VOXnn Range: 01 – 10
In case of extreme cockpit noise or uncompensated microphones the VOX
system can be deactivated by selecting VOX: 01. When VOX is
deactivated, the intercom can only be used by means of intercom
switches.
3.4.4. TXm – PTT Switch Selection
Pressing the AUD button three times enables the turning knob to select
certain PTT switches. In addition when one of both PTT switches is disabled
(not-Both) the respective microphone channel is disabled during trans-
missions.
TXm** *- Left / -* Right / ** Both

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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3.4.5. INT – Intercom Volume
Pressing the AUD button four times enables the turning knob to set the
intercom volume.
INTnn Range: 01 - 10
3.4.6. EXT – External Audio Input Volume
Pressing the AUD button five times enables the turning knob to set the
external audio input volume. External audio inputs can be audio alarms, voice
alarms, music etc.
Activation occurs for settings >00 and will be indicated by the flag “a”.
EXTnn Range: 00 - 10
3.4.7. DIM – Display Brightness (Batt.-voltage)
Pressing the AUD button six times enables the turning knob to set the
display brightness.
Display lighting current drain at maximum
brightness is only 10mA. Maximum
brightness is glare free even in darkness and
can be used continuously.
Indication of battery voltage (VDC).
DIMnn Range: 01 – 10
3.4.8. CON – Display Contrast
Pressing the AUD button seven times enables the turning knob to set
the display contrast.
CONnn Range: 01 - 10
3.4.9. SIT – Side tone
Pressing the AUD button eight times enables the turning knob to set
the side tone volume.
SITnn Range: 01 – 10

User & Installation manual
VHF- Communication Transceiver
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KRT2 & KRT 2A
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3.4.10. MIC – Setup
Each of the two microphone inputs channels can be configured
individually, which enables different microphone types to be used.
A maximum of two microphones of same type may be connected to each
microphone input channel (see Microphone Connection 5.6.1).
The MIC – Setup is the last item of the Audio menu and can be accessed
by pressing the AUD button nine times.
By pressing the DUAL button repeatedly L, R and AUTO can be selected.
L (R) means left (right) microphone input channel. The AUTO function is
explained later.
By means of the turning knob the displayed microphone input channel
amplifier gain (MIC-level-01-=-low-gain,-09-=high-gain) can be selected
individually. The microphone signal level is dynamically displayed as bar
and as numeric value (from-0.00-to-1.00) in the line below.
The initial MIC-level should be 05, the engine should be running, use a
headset or earphone and speak at a normal voice level to fine-tune the
MIC-level. Whenever a new MIC-level was selected, the dynamic bar
indicator should then be at about 50%.
When the microphone setup menu is left, the new value is stored.
The range of the MIC-level for standard microphones is 01 to 09.

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VHF- Communication Transceiver
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MIC levels 10 and 11 are special settings for low microphone
levels like dynamic micro-phones often used in gliders.
10 is used for non-amplified Electret microphones with a 8 volt
supply voltage.
11 is for dynamic microphones only.
In the AUTO mode every 30 sec. the left microphone impedance
is measured. When using an Electret microphone and a dynamic
microphone is recognized, internal switchover to the dynamic
microphone type and vice will take place. When using a dynamic
microphone and an Electret microphone is recognized, internal
switchover to the Electret microphone type will take place.
Microphone type switch over always affects both microphone
channels.
The present recognized Type will be indicated (Mic: dyn/std).
To activate the recognition instantly leave AUTO and come back.
The MIC submenu is left by pressing the AUD button.
Additional indications
Additional indications for test purposes
AGC: ..... HF receiver Automatic Gain Control
Ext: ..... External audio input voltage
Mic: dyn or Mic: std
Indicates, which microphone type was selected either by the user or
recognized in the AUTO mode.