SV-XPNDR-26X Installation, Configuration, and Testing
SkyView System Installation Guide - Revision K 11-9
External Standby Input (optional)
This input, when held low, places the transponder in Standby mode. It should be used to switch
between transponders in an installation with two transponders. The input is active low, and will
be asserted when the voltage to ground is pulled below approximately 4 Volts.
TSO Serial GPS Position Input (future use)
ADS-B OUT transmissions that meet the 2020 FAA ADS-B equipment mandate require that a
TSO’d GPS signal of sufficient integrity be directly provided from the GPS to a capable ADS-B
device (such as the SV-XPNDR-26X). For this purpose, a dedicated serial input is provided on the
SV-XPNDR-26X module that allows an appropriate GPS receiver serial output to be connected
directly to the SV-XPNDR-26X. At the time of writing, the SV-XPNDR-26X is certified to TSO
C166a. The FAA has recently mandated TSO C166b for NextGen implementations that meet the
2020 ADS-B equipment mandate, and a TSO-C166b software upgrade for the transponder is
planned. This means that currently, the SV-XPNDR-26X’s ADS-B transmissions are not at a high
enough integrity level to meet the FAA’s 2020 ADS-B equipment mandate. Therefore, the SV-
SPNDR-26X currently ignores all TSO’d GPS signals that may be connected to this input. It will
be utilized in the future upon the availability of SV-XPNDR-26X software that meets TSO-C166b
and certified GPS output that meets the requirements of the FAA’s 2020 ADS-B mandate.
Antenna Installation
The antenna should be installed according to the manufacturer’s instructions.
The following considerations should be taken into account when siting the antenna:
The antenna should be well removed from any projections, the engine(s) and
propeller(s). It should also be well removed from landing gear doors, access doors or
others openings which will break the ground plane for the antenna.
The antenna should be mounted on the bottom surface of the aircraft and in a vertical
position when the aircraft is in level flight.
Avoid mounting the antenna within 3 feet of the ADF sense antenna or any COMM
antenna and 6 feet from the transponder to the DME antenna.
Where practical, plan the antenna location to keep the cable lengths as short as possible
and avoid sharp bends in the cable to minimize the VSWR.
Electrical connection to the antenna should be protected to avoid loss of efficiency as a result
of the presence of liquids or moisture. All antenna feeders shall be installed in such a way that a
minimum of RF energy is radiated inside the aircraft.
Antenna Ground Plane
When a conventional aircraft monopole antenna is used it relies on a ground plane for correct
behaviour. For ideal performance the ground plane should be very large compared to the
wavelength of the transmission, which is 275 mm. In a metal skinned aircraft this is usually easy
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