Trig Avionics TX56 User manual

TX56/56A and TX57/57A Nav/Com Operating
Manual
01775-00-AC
18 May 2022
Trig Avionics Europe B.V.
Hardwareweg 3
3821 BL Amersfoort
Netherlands
© Copyright 2019
EN/DE/FR

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Applicability
This operating manual covers both the TX56/TX57 (8.33 kHz and 25 kHz
channel spacing) and the TX56A/TX57A (25 kHz only channel spacing). Apart
from the channel spacing and higher transmit power for the TX57 and TX57A
all other functions are identical, and any references to the TX56 will also apply
to the TX56A, TX57 and TX57A unless stated otherwise.
Front Panel
Display Modes
The display is divided into two windows. The left part of the screen shows the
primary and standby frequencies and icons to indicate the operating mode of
the communication radio. The right part of the screen shows the primary and
standby frequencies and icons to indicate the operating mode of the
navigation radio. The knobs and switches are shared between the
communication radio and the navigation radio; which is being controlled is
shown by the size of the corresponding display window.
In communication radio mode, the dividing bar moves to the right and the
communication radio window occupies most of the screen. In this mode the
knobs and buttons control the behaviour of the communication radio.
In navigation radio mode the dividing bar moves to the left and the navigation
radio window occupies most of the screen. In navigation mode the knobs and
buttons control the behaviour of the navigation radio.
Com Radio Display
Press the COM button to enable com display mode. The primary com
frequency is on the left and the standby frequency is on the right half of the
window.

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The right hand concentric knobs are used to tune the radio. The large knob
adjusts the MHz portion of the standby frequency, and the smaller knob
adjusts the kHz portion of the standby frequency. To activate that frequency,
press the Flip-flop button. This moves the standby frequency to the primary
position, and puts the primary frequency into the standby position.
The TX icon shows that the radio is transmitting. An RX icon shows that the
frequency is active and the audio will be heard through the headphone and
speaker outputs. The standby frequency will only be received during the
MONITOR function which is indicated by a +2 icon when active.
Nav Radio Display
Press the NAV button to enable Nav display mode. Like the com radio
window, the primary Nav frequency is on the left and the standby frequency is
on the right. The right hand concentric knobs are used to tune the standby
frequency, and the Flip-flop button exchanges the primary and standby
frequencies.
The Nav receiver will automatically decode the received radial for a VOR if it
is in range, and display it below the frequency. It will also automatically
decode the Morse code identifier, and display that as well. The identifier is
only displayed after it has been heard twice correctly, so there can be a delay
of up to 60 seconds before it appears. If the station is out of range, and until
the signal has been decoded, these fields will be dashed, “---“.
The standby Nav frequency can also be received by selecting the MONITOR
function, in which case both radials will be shown.
If either the primary or standby frequency is an ILS/LOC there is no radial
information, and the word LOC is displayed instead of the radial.

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OBS Display
If your configuration supports it – determined by the type of Course Deviation
Indicator installed in your aircraft – pressing the OBS button displays a small
version of the CDI on the Nav/Com screen.
If you don’t have a CDI connected to the Nav/Com, this mode provides a built-
in deviation instrument. The left/right movement of the on-screen needle
indicates the course position relative to the aircraft position. When the
needle is in the middle the aircraft is on the selected radial. A To/From flag
will be shown to indicate whether the course is inbound or outbound. The
right hand knobs (the tuning knobs) act as Omni Bearing Selector knobs, and
allow you to select the desired VOR radial. As a short cut, if the tuned VOR is
in range pressing on the end of the tuning knob will slew the OBS value to
match the current radial.
If you have a conventional CDI, like the Trig TI106, or a digital “glass” CDI the
Omni Bearing Selector (OBS) knob on the CDI itself will control the radial
selected for the Nav/Com CDI, and the left/right movement of the main CDI
needle will be repeated on the screen of the Nav/Com. The tuning knobs on
the Nav/Com will have no effect.
If the tuned station is out of range, the CDI display will be crossed out and no
left/right needle will be displayed.
If you have an external CDI which has its own built-in converter, such as a
legacy Bendix/King indicator, OBS mode will not be available – you should use
the external CDI in the usual way.
T/F (To/From) Button
When the nav receiver is tuned to a VOR that is in range the system will
decode the radial that you are flying over. The normal display is the radial
from the beacon – that is, the outbound radial. If you want to see the

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magnetic track to follow to get to the beacon, pressing the T/F button will flip
the display to show bearings to the beacon. Pressing again will toggle back to
displaying the radial from the beacon.
Localizer Back Course Approaches
In some parts of the world there are approaches based on tracking a localizer
back course. The Nav/Com can automatically reverse the course indications
for you, so that the CDI needle works in the correct sense. If a localizer
frequency is active on the primary Nav channel, press and hold the T/F button
for 5 seconds to turn on the Back Course sensing. An icon BC will be shown on
the screen, and if you are using a Trig TI106 CDI, a BC annunciation will also
appear on the CDI.
On/Off, Volume, Squelch, Ident Knob
The left hand knob controls the power to the radio and adjusts the audio
volume. Turning this knob clockwise will switch on the radio and then
increase the volume. Turning anticlockwise will reduce the volume and
eventually will click off. Both the com radio and nav radio volume are
controlled at the same time, regardless of which screen is showing.
When the display is in communication radio mode, pressing the end of this
knob toggles the automatic squelch on and off, which can be used to listen for
faint stations or as a simple audio test.
When the display is in navigation radio mode, pressing this knob toggles
between voice mode and ident mode on the nav radio receiver. Voice mode is
used to listen to ATIS or other communications on a VOR station. In voice
mode the display shows a Vicon. Ident mode filters out most of the
background noise (and voice transmission) and allows you to listen just to the
Morse code identifier. This is especially useful when the signal is faint. Ident
mode shows an ID icon.
If the Nav/Com has been configured for stand-alone use without an audio
panel, a third choice is available which is to mute the Nav audio altogether –
neither icon is shown in this case. Press the knob in nav mode to cycle through
the choices.
The internal decode of Morse code identifiers does not depend on the setting
of the audio output.
Com Radio Tuning Step Size
When tuning in com mode, pressing the end of the tuning knob changes the
channel spacing that the small knob operates through. If the radio is
configured for 8.33 kHz operation, the steps toggle between 8.33 kHz
channels and 25 kHz channels. If the radio is configured only for 25 kHz
operation, the steps toggle between 25 kHz and 50 kHz channels.

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Changing the step size does not change the behaviour of the radio, only the
tuning knob step size – it helps to quickly tune a frequency.
The TX56A does not support 8.33 kHz operation and so the steps will only
toggle between 25 kHz and 50 kHz; again, changing the step size does not
change the behaviour of the radio and only changes the step size between 25
kHz and 50 kHz.
MON Button
The com and nav radios include a dual-frequency listen feature; pressing the
MON button toggles this feature on and off. The monitor mode can be
enabled separately for the com and nav radios; press the MON button whilst
on the appropriate screen.
When the com monitor is active, a +2 icon appears next to the standby
frequency, and the radio will scan between the active and standby frequencies
listening for transmissions. The primary channel has priority – a transmission
on the primary channel will interrupt the secondary channel. As an aid to
identifying which channel is active, the RX icon will light next to the active
channel and the secondary channel will appear slightly quieter than the
primary. If your radio is wired for stereo and you are using a stereo headset,
the secondary channel will also appear to be to the right of the primary
channel.
This is useful in an aircraft with only a single radio since it allows you, for
example, to copy the ATIS whilst maintaining a listening watch on the ATC
frequency.
When the nav mode is active, pressing the MON button activates the standby
VOR frequency and displays the radial of the standby VOR. This allows you to
find an intersection of two beacons with only a single Nav/Com receiver. The
primary VOR/LOC will be displayed as usual on your CDI, whilst the secondary
radial can be read on the screen.

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Dual watch is also available when you are using the internal CDI display. The
primary Nav channel (LOC or VOR) will be shown on a small CDI display while
the secondary VOR is also decoded and displayed.
Nav dual frequency operation is not possible if the primary CDI has a built-in
converter, such as a legacy CDI or an Aspen PFD.
During dual frequency operation you cannot listen to the Ident for
verification, and the Nav/Com will not identify the beacon for you. You
should always verify you have the correct beacons tuned before you switch to
monitoring both.
PLAY Button
The com radio includes a digital audio recorder. Pressing the PLAY button will
automatically replay the previous transmission received. During playback the
PB icon will be displayed on the screen.

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If a new transmission is received during playback, the playback is cancelled
and the live transmission will be heard instead.
Intercom Function
The Nav/Com has a built in intercom which can be installed as permanently
engaged or selected via a switch. The intercom is voice activated and the
audio is routed through to both of the headsets. The intercom squelch and
volume can be adjusted independently from the radio function through the
configuration menu.
Frequency Database
The Nav/Com has up to three types of database containing frequencies and
station identifiers for both com and nav frequencies. One is stored in the
radio and configured by the pilot; it will always be available. One is a list of
the ten most recently used frequencies; it will be populated automatically as
you use the radio. The third is only available if your Nav/Com has been
connected to a compatible GPS receiver, and contains frequencies loaded
from the GPS database.
Note that the TX56A is only able to store and recall 25 KHz com channel
frequencies.
To access these databases press the MEM button whilst in the applicable
mode – there are separate com databases and nav databases. The right hand
part of the window will be replaced with the database screen which always
starts on the pilot created database.
The large knob moves the highlighted cursor, whilst the small knob selects the
value at the cursor.
Airfield or facility identifiers are in alphabetical order. Use the small knob to
scroll through the identifiers until you find the one that you want. Move the

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cursor using the large knob to highlight the station type, and then select one
with the small knob, for example GND, TWR or APPR.
Pressing the MEM button at any time puts the currently selected result into
the standby frequency and returns to the normal operating screen. Pressing
the Flip-Flop button puts the currently selected result into the active
frequency instead, and returns to the normal operating screen.
Recent Frequencies
There is also a memory of the ten most recent frequencies that you have used.
From the initial memory screen, move the cursor using the large knob to
highlight the MEMORY caption, and turn the small knob to select the RECENT
database.
Move the highlight onto the frequency, and you can scroll through the ten
most recently used frequencies.
GPS Database
If it has been configured in your aircraft, there is a third type of database in
the radio. This is loaded by your GPS receiver and will contain airfields
appropriate to your current route of flight, as well as nearby beacons and
ILS/LOC frequencies.
It is accessed exactly the same way as the built in database, except that you
first select the remote data source using the large knob (to highlight the
database field) and the small knob (to select the GPS data source).
The only difference is that airfield and beacon identifiers are usually ordered
by how close they are to your route, rather than alphabetical order.
Entering New Frequencies
You can add station identifiers and frequencies to the internal databases,
which store up to 250 entries. The process is the same for com and nav