SV-XPNDR-26X Installation, Configuration, and Testing
11-8 SkyView System Installation Guide - Revision K
Connect the SV-XPNDR-26X RX wire (pin 5) to the SkyView serial TX of your choosing. If
you have multiple displays, the transponder RX wire must be connected to a serial TX
wire on each display.
Record the SkyView serial port that you have chosen on each display as you will need to
configure it later for use with the transponder.
Mutual Suppression (optional)
Mutual Suppression allows two or more transmitters on adjacent frequencies to inhibit the
other transmitters when one is active to limit the interference effects. It is commonly used
between transponders and DME systems, and between transponders and collision avoidance
systems. Most installations will not make use of this feature, since most Dynon-equipped
aircraft have only one transponder and often do not have DME equipment or other active
traffic system that interrogate other aircraft.
The Mutual Suppression pin (18) is an ARINC compatible suppression bus interface, which acts
as both an input and an output. The SV-XPNDR-26X will assert this signal when it is transmitting,
and can be suppressed by other equipment that asserts the signal. The SV-XPNDR-26X will
drive approximately 24 Volts on the output (independently of supply voltage), and will treat the
input as active whenever the bus has greater than 10 Volts.
If you are using the Mutual Suppression feature, simply connect all of the Mutual Suppression
wires from devices that use them together.
Ident Switch Input (optional)
SkyView has an IDENT button in its transponder menu that is normally used to ident when
requested by ATC. However, the ident switch input allows the IDENT function to be selected
using a remote switch. The input is active low, and will be asserted when the voltage to ground
is pulled below approximately 4 Volts. Therefore, a momentary switch to ground should be
installed on this output if a remote ident switch is desired.
Squat Switch Input (optional)
The Squat switch input allows the transponder to automatically switch between Airborne and
Ground modes, and affects both the Mode S reply behaviour and the ADS-B reporting behavior.
The input will be asserted when the voltage to ground is pulled below approximately 4 Volts.
The logical sense of the input can be programmed to be either active low or active high in the
SkyView Setup Menu.
This must be a mechanical switch that accurately reflects the aircraft’s on-ground status. Mode-
S certification requirements state that this cannot be a simple airspeed switch.
On an aircraft with no appropriate squat switch circuit this input should be left unconnected,
and the transponder programmed to ignore the input.
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