Local Oscillator 0 50 0. MHz uf A T V dc / A Power Supply R0 R0 0 0 k n 0 00uH V 00 L0 0 +.V k N 0 0-0mV +0 V x N 55V 0 0 k 50mA MHz n 5 50 5k C 5 0 ON/OFF 0 MC IF AMPLIFIER n RFC p C0 W N05 STC50 5-0 00Mc k k Mixer 00Mc POWER SUPPLY N k 0 x uf volt. adj 500 0 00Mc bus 50p 00 00uH Self test module 0 k antenna C-connector -0V 00 uf N5 pins on main plug at rear of box pin on a module x N ( Ge pnp) 0 x 0.5uF- 00V 5 0 TRANSMITTER PRESSURIZED x nf k isolator x k 5 N0 INVERTER + kv 5 0 khz k Tune at 00Mc uf 00k T integrated in transmitter module ML55K k 0 k -0 V 0 0 00 00 hour meter MODULATOR N0 0 sec Power-up delay 0 Pulse equal M5 0p WILCOX A RF modules 05--0 kb k ntc White +0 50k k uf 00 uf Automatic Overload Control (AOC) 50 k n 5k k out k 5u 0 R5 00 k +.V 0 5x N 0k N k 0 0k 00 00 k CODEC See next page Power up delay standby
There are several modes of interrogation, each indicated by the difference in spacing between two transmitter pulses, known as P and P. Each mode produces a different response from the aircraft. A third pulse, P, is for sidelobe suppression and sent us after P with an omnidirectional antenna at a higher level than the sidelobe, but lower than the main lobe. If P is higher than P, the transponder should not respond. Mode military civil Distance between P - P (±0.) µs 5 (±0.) µs A (±0.) µs mode description Military Identification Military mode is used to support military identification codes (although 0 mode codes could also be used). Normally, the codes could be used to indicate role / mission / type. However, this mode itself is not in common use in a normal peacetime environment. Military Identification Military mode provides 0 ID codes for military use (as for mode A). Normally used to identify an individual aircraft airframe. Civil / Military Identification Provides 0 ID codes for civil / military use. The commonly used mode B (±0.) µs not used C (±0.) µs D 5 (±0.) µs not (never) used Civil, Pressure Altitude Extraction mode C is used to extract the pressure altitude mode C value (or true altitude if below the transition altitude). Antenna coupler test n N 0 0 uh 5. MC 0 5 khz modulator 5 N 00 n 0n k 5n 5kc uh Pulse uh UHF oscillator 50p 0 k Trigger level k 50 us N X k us k 0 00MHz, -55 dbm 0 N 50 +0 0n 5k n N 5 0 n k 50k u P 0 Self test module 0 ma N0 ms u uf 5 PASS V 0mA Module Self test This module (P0) is mounted optionally in the Wilcox A transponder. Press the test button on the front or on the control panel for a few seconds. The self test module then continually interrogates the transponder in mode /A. Once an interrogation is recognized, the IF strip is cut-off, and a response is made according to the present code switch setting. Any response from the transmitter is detected by the selftest module, and will turn-on the PASS lamp. This also happens with a regular (in flight) interrogation, however at a much lower rate as there only a few interrogations per second. Wilcox A Built-in Test module 5--0 kb
From IF Pin RCVR OUT 0. k pulse track 0. k k p F 0.µs to IF Strip pin +V normal receive <+V blocked to IF pin a P 0 k 0 0. 0. k 0. p k N0 k 00 k 0k 0p k k 0. k 50k k 00 N 50p AOC Automatic Overload Control -0V P 0 Video Amplifier 5 0 0k 50 0. k k 0k.uF 50k N0 0 + NPN N PNP N0 Unless otherwise noted + 0n 0.uF k k 0k + -0v Pin on module connector 50k.u 50k Pin on 5-pole main connector a 0-0V 0 Modulator pin SLS Main gate 500 0.µs input 50.µs.µs.µs.5µs.µ.5µ 0.µ 0.5µ.µ.5µ 0.µs 0 +.V bias 0 5 P 0 00k 50 k 00k 0 5 k k k 00k 0k k sidelobe 00k 50k k MODE /A 50k k k 50k k MODE D identity MODE C altitude 0 0- (option) AOC k k k k 0 k 00k k k 0. k 0. k 0 WILCOX A Transponder Decoder Boards --0 kb page 0 +V 5us SUPPR k k k P 50 k k k k P 0 k k Pwr-on Reset Modltr Pin k -0v k k u k u 00k 00k 00k 0 0 0 P 0 k 00 k 0 0 0 0 0 0 SLS 0 0 k k k k 0 k k k 0 k k k k k 0 n 00 5k 5k 5k k 0n 00 0n k 5k -0V 0n k 5k -0V 0n k -0V 0- -0v 0p 5k u 0-0V Main gate c u u u Ext Trig Modltr- SUPPR 0Vpp 5us 0-50 pin 0 pin 0 pin
Main gate From mode gates +0V 5us 0-0V -0V -0V Start 0 khz 5k 5k 5k 00 p Main Gate 5 5k k 5 N 00 k P50 P0 P0 0-0 00uH p k 0kHz clock burst 5 50 n 0 0 0 5 J B P C 0.uF 0 0 0n k 0 00 0.uF MODE /A 0 + 5 MODE C MODE D 0 R D N E S 00 0k P 0-0V To Modulator 0 5 0 Pulse coder J0, J0, J0 and J50 --0 kb F T H U W 0 5 5 5 ( clock ) IPS Pin on module connector Pin on 5-pole main connector n p Vpp N -0 +V P 50-0 +0 k +.V k 5k k 5k c k 5 + -V -V Blank altitude N0 5 N 5k 0n Shift register P 0 and P 00 5k - 0 +V -0V NPN N PNP N0 unless noted sec. 5 IP delay IP k 0uF k k -0V I/P HiSens M 0k 5k Self test command 5 +0 Self test result Mode D enable L M K Mode /A code Mode /A code Mode C code Mode C code 5 pole Main connector 0n N X N 00k J V U W X T Mode B enable A H k P S 0n +V B R Mode A enable Stdby +0 Diode switch detail IPS F 0 pole Mode D Connector on front C E D 5 Blank altitude On Spare wire Not connected
P 0 P 00 +V 5 00 5 00 0 k 0 khz 50 n p Resync Xmit pulses.uf n k k -0 clock 0 5 n 5 0 0 n 0 0p k ( 0 Main gate 5 0n 0 0 0 5 0n 5 ) IPS + bus To diode matrix P 0 All transistors N0 Shift registers Boards J0 and J00 okt 0 kb
The transmitter 0 HV transformer HV rectifier and buffer Caps Moveable part ML 55K Disc triode The transmitter module includes the High Voltage dc supply and the cavity with the self-oscillating planar triode ML 55K without radiator. Tuning is done from the front panel of the Wilcox A to set the frequency at 00 MHz. The output power is.5 kw pulse ( 0.5us wide) HV supply The kvdc high voltage capacitor (x 0.uF in series is 0.uF effective capacitance) is permanently connected to the anode of the planar triode. During a transmit pulse, A anode current during 0.us is drawn from this capacitor, causing a voltage drop of x 0.us/0.uF = 5V. A series of (worst case) 5 such pulses in rapid succession gives a voltage drop of 5V, about 0% of the high voltage. The inverter with toroid transformer and rectifier supplies about 0mA to recharge the capacitor to kv even with 000 interrogations per second. The average input is kv x 0mA = 0W, the average RF output is 5W. Oscillator The C look alike triode operates in (RF) grounded grid with a tuned anode cavity and a quarter wave cathode cavity. Fingers from anode to cathode cavity provide for feed back and to start oscillation quickly. During the transmit pulse of 0.us, there are only 0 cycles of the 00MHz RF frequency. RF output filter The coax system from cavity to antenna has a low pass filter to reduce the second harmonic, and an isolator to protect the triode from mismatch 0 grid 50 mm Fingerstrip contact O-seal WILCOX A Transponder Transmitter module