Wulfsberg Electronics Division VC-401B Benutzerhandbuch
Series III Avionics
Pilot's Guide
Page 18
TRS-42A ATC Transponder System
General Description
The Chelton TRS-42A ATC Transponder System is a digital, microprocessor-controlled 325 Watt
transponder that allows positive identification in the Air Traffic Control environment. Features include:
transponder that allows positive identification in the Air Traffic Control environment. Features include:
Dual transmitter output devices
Encoding altimeter readout
Dual transponder control from a single Control Display Unit.
Full-time automatic and pilot-selected self-test
"Quick-select" VFR mode
The TRS-42A system consists of a TR-421B Transmitter/Receiver and a CD-422B Control Display Unit.
The TR-421B Transmitter-Receiver unit assures accurate and dependable service. The unit provides
4,096 discrete response codes plus modes A and B, as well as mode C - altitude reporting (when
connected to an encoding altimeter). The unit uses a single-chip microprocessor to assure code data
validity and condition of all critical circuits.
4,096 discrete response codes plus modes A and B, as well as mode C - altitude reporting (when
connected to an encoding altimeter). The unit uses a single-chip microprocessor to assure code data
validity and condition of all critical circuits.
The CD-422B Control-Display Unit has the unique capability to control a dual transponder installation with
a single control head. Selection is made by simply pressing a selector button on the front panel.
a single control head. Selection is made by simply pressing a selector button on the front panel.
The CD-422B also provides an annunciation of the letters "ID" whenever the transponder replies to an
interrogation. When the mode selector is in the VFR position, the active transponder is channeled to the
1200 code (VFR). This code may be programmed to other international VFR codes.
interrogation. When the mode selector is in the VFR position, the active transponder is channeled to the
1200 code (VFR). This code may be programmed to other international VFR codes.
To aid in channel selection, the code selection knobs of the CD-422B provide variable-rate tuning for
greater speed and accuracy. Rapid rotation of a knob causes large changes in the code, while slow
rotation changes code digits slowly, one digit at a time. Also, there is no need to change to standby mode
before changing channels, because the new code will not be transmitted until the selector knobs have
remained stationary for 3 seconds. Whenever an emergency code from 7500 to 7700 is selected, the
display will blink on and off for 3 seconds before transmission.
greater speed and accuracy. Rapid rotation of a knob causes large changes in the code, while slow
rotation changes code digits slowly, one digit at a time. Also, there is no need to change to standby mode
before changing channels, because the new code will not be transmitted until the selector knobs have
remained stationary for 3 seconds. Whenever an emergency code from 7500 to 7700 is selected, the
display will blink on and off for 3 seconds before transmission.