Textron 172R180HP, Pilot Operating Handbook

Page: 294 / 396

SECTION 9 - SUPPLEMENTS
SUPPLEMENT 2- FAA APPROVED
CESSNA
MODEL 172R
3. MODE ANNUNCIATORS - Displays the operating mode of the
transponder.
4. REPLY INDICATOR (R) - "R" is illuminated for momentarily
when the transponder is replying to a valid interrogation and
during the 18 ± 2 seconds following the initiation of an ldent.
5. MODE SELECTOR KNOB - Controls application of power and
selects transponder operating mode as follows:
OFF - Turns set off.
SBY - Turns set on for standby power and code selection.
"SBY" is annunciated.
TST - Self-test function. The transmitter is disabled. All
display segments will illuminate.
ON - Turns set on and enables transponder to transmit
Mode A (aircraft identification) reply pulses. ON is
annunciated.
ALT - Turns set on and enables transponder to transmit
either Mode A (aircraft identification) reply pulses and
Mode C (altitude reporting) pulses selected
automatically by the interrogating signal. ALT is
annunciated.
6. VFR CODE BUTTON (VFR) - Pressing the VFR Button will
cause a pre-programmed Mode A reply code to supersede
whatever Mode A reply code was previously in use. Button
illumination is controlled by the RADIO LT dimming rheostat
7. CLEAR BUTTON (CLR) -- Pressing the CLR button will delete
the last Mode A code digit entered.
8. NUMERIC KEYS 0-7 - Selects assigned Mode A reply code.
The new code will be transmitted after a 5-second delay.
Figure 1. Bendix/King KT 76C Transponder with Blind Encoder
(Sheet 2 of 2)
S2-6
Dec 2/96