Garmin GTX 320 ATC Radar Detector User Manual
Contents
1. Pad ea 3 1 9 2 Ble an se aa Fen attest tan Ole na E ed 3 1 3 2 TESTING teat ie xcu ter Uere ea 3 5 SECTION 4 DISASSEMBLY AND REASSEMBLY INTRODUC HON lm 42 INSPECTION M Tm 4 3 FRONT SUBASSEMBLY at p i a mate ian INI pq trop nce re Spine pd pde Dudes nde 190 00133 02 Rev B SECTION 1 DESCRIPTION AND OPERATION 1 1 INTRODUCTION This manual provides all of the procedures principles of operation and information necessary to repair and maintain the GARMIN GTX 320 ATC Transponder Refer to GARMIN Installation Manual P N 190 00133 01 for installation and operating information 1 2 GENERAL DESCRIPTION The GARMIN GTX 320 Transponder is an integral part of the Air Traffic Secondary Radar Beacon System ATCRBS Figure 1 1 which consists of the following components INTERROGATOR In the ATCRBS the interrogator a ground based radar beacon transmitter receiver scans in synchronization with the primary surveillance radar PSR and transmits ground radar interrogation signals on a carrier frequency of 1030 2 MHz which repeatedly requests all transponders on the mode being used to reply The replies that are received are mixed with the primary surveillance radar returns and both are displayed on the same radarscope TRANSPONDER The GTX 320 Transponder is an airborn2. OFF SBY ON and ALT nomenclature shall all be illuminated at the reduced level The four reply code digits shall remain illuminated with no change in intensity The triangle shaped reply light must turn on and remain on while the switch is held in the TST position OK 3 Release the mode select switch from the TST position It shall freely snap back to the ALT position and the triangle shaped Reply Light shall turn off OK 190 00133 02 Rev B 3 11 3 3 3 17 Front Panel Test Reply Light 1 Rotate the Mode Select Switch from TST to ALT and with the unit not replying Increase the RF level on the ATC 1400A above MTL so that the transponder has a reply rate above 90 The triangle shaped reply light shall turn on OK 2 Rotate and hold the mode select switch in the TST position The reply light shall remain on while in the TST position OK 3 Release the switch so that it returns to the ALT position The reply light shall remain on OK 3 3 3 18 Numerical Reply Code Switches 1 Rotate the XPDR MODE switch on the ATC 1400A to position A 2 With the transponder mode switch in the ON position incrementally rotate the four reply code switches through each position Verify that the unit causes the ATC 1400A to display the same number on the XPDR CODE digital display OK 3 While the code switches are in a numbered detent position apply a light force against the knob from all directions Verify t
3. A Test Panel must be fabricated by the shop which meets the typical test setup criteria given Figure 2 3 Addition ally a corresponding test harness must be fabricated which allows for the necessary connections between J102 and the Test Panel Use Figure 2 3 as an aid in fabricating the test harness 2 3 2 Alignment Tool The alignment tool is used to adjust the transmitter frequency C620 and the transmitter power output C635 FLAT BLADE SCREWDRIVER XCELITE 186 Y 1 4 NUT DRIVER HOLLOW SHAFT XCELITE HS 8 Figure 2 1 Alignment Tool 190 00133 02 Rev B 2 1 2 3 3 Antenna Test Cable Connector The antenna test cable incorporates a BNC connector at the test fixture antenna and a male BNC blindmate connec tor GARMIN P N 330 00198 00 at the transponder Figure 2 2 shows the connector Follow accepted industry practices when installing the BNC connector Use the following instructions when installing the blindmate BNC 1 Trim coax outer insulation back inch 2 Trim braid not center conductor or insulation back 1 4 inch 3 Strip insulation back 0 120 NOTE If the outside diameter of the coax braid is smaller than the inside diameter of the center connector sidewall opening place the ferrule over the coax braid flush against the coax outer insulation before performing the next step 4 Insert cable center conductor dielectric and shield braid through the sidewall of the connector and sol
4. T T od t pment eee Figure 3 5 P1 P3 and SPI Pulses 3 3 3 12 Front Panel Test OFF Set the transponder mode select switch to the OFF position Only the OFF nomenclature shall be illuminated and all other panel lighting shall not be illuminated The unit s internal power supplies shall all be off OK 190 00133 02 Rev B 3 10 3 3 313 SBY Stand By Set the transponder mode select switch to the SBY position The SBY nomenclature and the four reply code digits shall be illuminated with a higher intensity than the OFF and TST nomenclature All internal power supplies shall be on but the unit shall not reply to any interrogations OK 3 3 3 14 ON Set the transponder mode select switch to the ON position The ON nomenclature and the four reply code digits shall be illuminated with a higher intensity than the OFF SBY ALT and TST nomenclature OK 3 3 3 15 ALT Altitude Set the transponder mode select switch to the ALT position The ALT nomenclature and the four reply code digits shall be illuminated with a higher intensity than the OFF SBY ON and TST nomenclature OK 3 3 3 16 TST Test 1 Decrease the RF level control on the ATC 1400A so that the transponder has a 00 reply rate 2 Rotate and hold the transponder mode select switch in the TST position TST
5. 0 5 MHz 7 Reinstall the cover over the transmitter adjustment holes OK 190 00133 02 Rev B 3 4 3 3 TESTING Perform testing after completing transmitter frequency adjustment 3 3 1 Test Equipment See paragraph 3 2 1 3 3 2 Test Setup See figure 2 3 3 3 3 Test Procedure 3 3 3 1 Turn On Delay NOTE The test setup will not work if any toggle switch on the ATC 1400A is placed in the incorrect position 1 Configure the ATC 1400A as shown in Figure 3 6 2 Turn the transponder mode select switch to the OFF position OK 3 Adjust the ATC 1400A Transponder Test Set to an RF level 69 dBm OK 4 Turn the GTX320 mode switch from the OFF to the ON position There shall be an approximate 5 second delay before the unit transmits OK 5 Rotate the mode select switch on the GTX320 to the ALT position The GTX320 shall continue to reply to valid interrogations OK 6 Rotate and hold the mode select switch on the GTX320 in the TST position The GTX320 shall continue to reply to valid interrogations OK 3 3 3 2 Reply Transmission Frequency 1 Set the transponder mode select switch to the ON position 2 Rotate the RF level control on the ATC 1400A to 69 dBm The XMTR FREQ display on the ATC 1400A shall read from 1087 MHz to 1093 MHz 1087 to 1093 MHz 3 3 3 3 Transmitter Power Output 1 Set the PRF thumb wheel switches to 1200 Hz The XMTR PWR display on the ATC 1400A shall read greater than 125 watts through the calibr
6. assemblies the Main PCB Assembly and the Front Subassembly 1 4 11 Main PCB Assembly Not Field Repairable The Main PCB Assembly contains the following circuits IF Amplifier and Pulse Discriminator Local Oscillator and Mixer Power Supply Programmable Logic Device Light Dimming Circuitry Modulator and Transmitter 1 4 2 Front Subassembly Field Replaceable The Front Subassembly consists of the following Reply Code Switches and Mode Function Selector Front Display and Knobs Backlighting Circuitry Front PCB Assembly 190 00133 02 Rev B 1 2 1 5 SCOPE OF MAINTENANCE Due to the overall complexity of the unit GARMIN recommends limiting field maintenance to the following Removal and Replacement of the Front Subassembly Transmitter Frequency Adjustment Transmitter Power Output Peaking Adjustment 190 00133 02 Rev B 1 3 SECTION 2 SPECIAL TEST EQUIPMENT 2 1 INTRODUCTION This section identifies the special tools and test equipment essential to repair the GTX 320 Standard equipment is not listed For any questions regarding special tools and test equipment contact the GARMIN Customer Service Department at the address listed on Page A 2 2 SPECIAL TOOLS AND TEST EQUIPMENT Test Harness Locally Fabricated Test Panel Locally Fabricated Alignment Tool Locally Fabricated Antenna Test Cable Connector Locally Fabricated 2 3 1 Test Panel and Test Harness
7. GTX 320 ATC TRANSPONDER MAINTENANCE MANUAL GTX 320 GARMIN 1200 E 151st Street Olathe KS 66062 USA 16 March 1999 190 00133 02 Rev B GARMIN This publication is the property of GARMIN It may not be reproduced or transmitted in any form whether printed or electronic without the expressed written consent of GARMIN International GARMIN 1200 E 15 1st Street Olathe KS 66062 USA Telephone 913 397 8200 or 1 800 800 1020 www garmin com REVISION RECORD REVISION DATE DESCRIPTION ECO A 04 24 98 INITIAL RELEASE B 3 16 99 REVISE AND REWRITE 10640 Copyright 1999 by GARMIN Corporation All rights reserved 190 00133 02 Rev B TABLE OF CONTENTS SECTION 1 DESCRIPTION AND OPERATION PARAGRAPH PAGE DIG ae iO te nec wh ad ae eet tea a ected 1 1 1 0 GENERAEDESGHBIPTION o rr rd cte mene inet 1 1 1 24 TEGHNIGALSPEGIFIGATIONS t este edet 1 1 1 4 EQUIPMENT DESCRIPTION ecd vett eio 1 2 1 5 SCOPE OF MAINTENANG Bigs roads 1 3 SECTION 2 SPECIAL TEST EQUIPMENT 2V INTRODUCTION m 2 1 2 2 SPECIAL TOOLS AND TEST EQUIPMENT eot t 2 1 SECTION 3 ALIGNMENT AND TESTING gi NIN TRO BUG TION Pads
8. O LON 0 YAWWIG LHBUT TINVd L3VuDuiv 1 YaWWId LHDUT TINVd 14v INIOd 1531 AS INIOd 1531 LNIOd 1531 INIGd 1531 AZL 03 211 5 01553 4405 TYNH31X3 15 TVNH31X3 IfidNI 2 Ld NI 83211010 3001111 42 LONI 837111910 92 LfidNI 93210919 5 LAANI 93711914 3Qf1LLLTV 1 93210910 SGNLIL TY L idNI 83211910 3001111 LAANI 43211910 117 LONI 9321014 LIL TY V LAANI 832111910 3001111 LY LOdNIE H3ZILIDIO LLLTV 006 XLD J102 Figure 2 3 Test Setup Test Harness 2 3 190 00133 02 Rev B SECTION 3 ALIGNMENT AND TESTING 3 1 INTRODUCTION This section of the manual consists of alignment and test procedures Perform the following procedures to iden tify failed units troubleshooting and after completing any repairs The procedures assume familiarity with the setup and operation of the special test equipment listed in Section 2 Units failing any part of alignment or testing must be returned to GARMIN for repair except for the front subassembly which may be field replaced 3 2 ALIGNMENT Field alignment of the GTX 320 is limited to adjusting the transmitter frequency No other attempt at alignment should be made Adjust the transmitter frequency before testing the unit 3 2 4 Alignment Equipment The following equipment or sui
9. ated 1 5dB coax gt 125 Watts 190 00133 02 Rev B 3 5 3 3 3 4 Minimum Trigger Level Adjustment MTL 1 Set the PRF thumb wheel switches to 500 Hz 2 Set the ATC 1400A XPDR MODE switch to position A 3 Reduce the RF level on the ATC 1400A test set until the nominal reply rate is 90 The RF level MTL shall be 69 dBm or less 4 Set the ATC 1400A XPDR MODE switch to position C The nominal reply rate should remain at 90 5 If the nominal reply rate is less than 90 then increase the RF level until the nominal reply rate is 90 The RF level shall be less than 69 dBm and shall not deviate greater than 1dB from the MTL in Mode A 6 Increase the RF level to 50 dB above MTL The reply rate displayed on the ATC 1400A shall be at least 90 gt 90 Reply Rate 3 3 3 5 Reply Pulse Characteristics 1 Set the oscilloscope to the following settings PARAMETER SET POINT EXT TRIG CH 2 XMTR Detected Video CH 2 VERTICAL SENS 20mV Div HORIZONTAL SWEEP 100ns DELAYED SWEEP CENTER ON FIRST PULSE 2 Configure the ATC 1400A front panel controls to the following settings PARAMETER SET POINT XPDR MODE MODEC PRF 500 Hz RF LEVEL 50 dBm SLS ECHO OFF FREQUENCY POWER TOGGLE SWITCH F P 3 Set the GTX 320 mode control select knob to the ON position The reply pulse will be visible on the oscillo scope as shown in Figure 3 2 The pulse shape must possess the qualities list
10. der the center conductor to the center pin of the connector NOTE When using low loss cable it may be necessary to flatten the solid wire center conductor slightly so it can fit the slot on the RF connector center pin When solder ing avoid applying excess heat to the connector body and center conductor insula tor 5 Heat the outside of the connector sleeve and at the same time apply solder between the braid and the sleeve 6 Continue to apply heat until the solder flows evenly 7 Install 50 ohm match 8 Insert connector cap and tack solder in two places STRIP DIMENSIONS CAP 12 1 0 25 6 4 7 0 12 50 OHM MATCH BUSHING 3 1 4 a BNC e E FERRULE Figure 2 2 Blindmate Antenna Connector 190 00133 02 Rev B 2 2 AWIL 1X3 340250711250 34 INAS V00 L 2 1V INE dNS AS Ifid dns LX3 J N SNILHDIT A A 82 HILIWLTOA BS E Ty Oo IEEE A INO SNIGVOT 32NVO3dHI HDIH 5 m C T 719901 YALIWLIOA WHO 0L Q30v019NlidS 91 T Eia 5 83804 NIVH E 20A LINIAN 9 5 25 D 28 0Lf 5 EZ ce 1 0 6l El VNN3INY H3M0d LANN
11. e radar transceiver It automatically receives interrogations from the ATCRBS and selectively replies with a specific pulse group code only to those interroga tions being received on the mode to which it is set Mode A no altitude information or Mode C automatic altitude information These replies are independent of and much stronger than a primary radar return The GTX 320 replies to both Mode A and Mode C interrogations on a carrier frequency of 1090 3 MHz with a rated power of 176 watts minimum at the antenna port The GTX 320 is also equipped with IDENT capability which activates the Special Position Identification Pulse SPI for approximately 20 seconds identifying that transponder return from other aircraft on the ATC scope RADARSCOPE The radarscope used by the controller displays returns from both the primary surveillance radar system and the ATCRBS These returns called targets are what the controller refers to in the control and separation of traffic 1 3 TECHNICAL SPECIFICATIONS Refer to the GTX 320 Installation and Operation Manual P N 190 00133 01 for technical specifications 190 00133 02 Rev B 1 1 AIRCRAFT Replys Lou SN 1090 MHZ OM PRIMARY 04 RADAR 7 INTERROGATE NN VU 1030 MHZ ECHO AN Be AS SSR GROUND INTERROGATOR a PSR SURVEILLANCE RADAR ATC SCOPE Figure 1 1 ATCRBS System 1 4 EQUIPMENT DESCRIPTION The GTX 320 consists of two major
12. e RF level to 3 dB above the MTL 4 Set the SLS ECHO thumb wheel switch to OdB 5 Flip the SLS ECHO toggle switch to the ON position The GTX 320 Reply shall have an average reading of 1 or less 6 Raise the RF level on the ATC 1400A to MTL 50 dB The GTX 320 96 Reply shall have an average reading of 196 or less lt 1 Reply Average Reading 3 3 3 9 External Suppression With the unit replying to interrogations apply a positive external suppression pulse of up to 100 microseconds and with a voltage amplitude of greater than 8 0 volts The unit must suppress the replies to any interrogations received during the time of the suppression pulse OK 3 3 3 10 External Altittude Encoder Inputs 1 Set the digital oscilloscope to the following settings PARAMETER SET POINT EXT TRIG CH 2 XMTR Detected Video CH 2 VERTICAL SENS 20MV DIV HORIZONTAL SWEEP 5 5 DELAYED SWEEP CENTER ON FIRST PULSE 2 Set the XPDR MODE switch on the ATC 1400A to position C The oscilloscope shall display the and pulses similar to Figure 3 3 OK 3 Rotate each of the four rotary switches on the GTX320 under test through at least one complete turn stopping on zero The unit shall not transmit any code information as evidenced by a change in the P1 and P3 pulse patterns The XPDR CODE digital display on the ATC 1400A test set shall indicate 0000 OK 4 Rotate the mode select switch on the GTX320 under test to the ALT
13. ed in the table below 190 00133 02 Rev B 3 6 PARAMETER SPECIFICATION Rise Time 50 100 nS Fall Time 50 200 nS Pulse Width 350 550 nS ek Run 500MS s Average Ch2 Rise 81 2ns Ch2 Fall 171 815 SANAS SANAA AAA f 435 9ns 20mV Sus Ch2 7 59 6mV i D 100ns Figure 3 2 Example Of Acceptable Reply Pulse 3 3 3 6 Dynamic Range 1 Set the GTX 320 mode select switch to the ON position 2 Set the 14004 SLS ECHO thumb wheel switch to 9 3 Flip the SLS ECHO toggle switch to the ON position 4 Increase the RF level to 50 dB above MTL a value of 21 dBm assuming an MTL of 71 dBm The percent reply shall be at least 90 as indicated on the ATC 1400A Reply 3 3 3 7 Automatic Overload Control AOC 1 Set the SLS ECHO toggle switch back to the OFF position 2 Increase the RF level to 3 dB above the MTL Set the PRF thumb wheel switches to 1200 Hz on the ATC 1400A test set The reply rate shall be 90 to 98 Note In order to obtain an accurate reading the unit must be warmed up before performing this test 90 to 98 Reply Rate 4 Reset the PRF thumb wheel switches to 500 Hz on the ATC 1400A test set 190 00133 02 Rev B 3 7 3 3 3 8 Side Lobe Suppression 1 Set the SLS ECHO toggle switch to the OFF position 2 Adjust the RF level on ATC 1400A to MTL so that the XPDR REPLY is 90 3 Raise th
14. fy that the transponder external surfaces have no dents etc 3 Inspect for bent or broken pins on the 25 pin connector 4 Inspect for damage to the BNC connector 4 3 FRONT SUBASSEMBLY P N 011 00263 00 1 Remove power to the unit 2 Remove the bottom cover 5 screws to expose internal circuitry 3 Remove the four black screws holding the front bezel to the frame 4 Carefully remove the Flex Strip from the Main Board Install according to Figure 4 1 to prevent incorrect installation crystal Y501 is included in the figure for reference purposes CAUTION When reinstalling the bottom cover ensure the proper screws are used to prevent the possible shorting out of Main Board Components 190 00133 02 Rev B 4 1 MAIN BOARD o o o o o o CRYSTAL Y501 Figure 4 1 Front Subassembly Installation 4 4 CLEANING After reassembly clean the external surface of the transponder when inspection shows dirt smudges etc Wipe with a damp lint free static free cloth 190 00133 02 Rev B 4 2
15. hat the digit displayed on the ATC 1400A test set does not include any intermit tent numbers OK 190 00133 02 Rev B 3 12 FRONT VIEW DISPLAY SELECT UNIT UNDER TEST DME PRF vg uy DME DIST XPDR REPLY XMTR FREQ we XMTR PWR ware FREQ j FRE f E RF LEVEL DME REPLY RANGE VEL ACCEL PRE SWTR Bes n YS aoo O 2 W XPDR P P DEV DME B DEV XPDR PULSE WIDTH SLS ECHO AH oW NARROW OFF OFF eS 4 TACAN IDENT Mm LES mo pane lon gt orr cove onS orr j van Great on Gore i NMi 6 TASMAN SUPPRESSOR OFF 3 MAN EON 2 TAC WIRE DSCRMINATOR PULSE SYNC GEN XMTR A SZ SZ 2 LINE DECODER INST DIM WIDE al 9595750509909 A A 0899999999599 c Q 0 BAD ust Figure 3 6 ATC 1400A Test Settings 190 00133 02 Rev B 3 13 SECTION 4 DISASSEMBLY AND REASSEMBLY 4 1 INTRODUCTION This section covers only the disassembly that is necessary to remove a faulty Front Subassembly Reverse the steps for assembly 4 2 INSPECTION Perform the following inspection and cleaning before disassembly 1 Verify that all screws are secure and in place 2 Veri
16. nit to warm up for approximately ten minutes before setting frequency 4 Rotate the frequency adjust slug C620 figure 3 1 with the screw driver portion of the transmit adjustment tool to a frequency of 1089 5 0 5 MHz Observe the frequency display on the test set Tighten the lock nut when finished 1089 5 0 5 MHz 190 00133 02 Rev B 3 2 1 C635 PA PEAKING v GL ADJUSTMENT C 5 NOTE REMOVE ONLY THIS COVER C620 TRANSMITTER FREQUENCY ADJUSTMENT Q o Figure 3 1 C620 and C635 Location 190 00133 02 Rev B CAUTION Do not allow the transmitter to oscillate below 1080 MHz as indicated on the ATC 1400A Test Set or else damage may occur to the mixer PARAMETER SPECIFICATION Frequency 1089 0 to 1090 0 MHz XMTR PWR 125 Watts Minimum through 1 5dB coax Pulse Rise Time 50 nS to 100 nS Pulse Fall Time 50 nS to 200 nS Pulse Width 350 nS to 550 nS 5 Adjust C635 for maximum power output as read from the ATC1400A test set The power must be greater than 125 watts gt 125 Watts 6 Verify that the frequency is still 1089 5 0 5 MHz Ifthe frequency is out of tolerance then loosen the locknut on C620 set the frequency within specification and then tighten the locknut while maintaining the frequency specification 1089 5
17. position OK 190 00133 02 Rev B 3 8 5 Successively turn on each altitude toggle switch on the test panel OK 6 Altitude coded pulses shall appear between the and P3 pulses as viewed on the oscilloscope and shown Figure 3 4 OK 7 Verify that the unit is correctly encoding the altitude by observing the XPDR CODE digital display on the ATC 1400A when each set of altitude switches A through D are toggled OK lek Run 10MS s Average E P3 m Z mv 7 50045 Ch2 7 59 6mV D 55 Figure 3 3 P1 and P3 Pulses lek Run 10MS s Average E P1 P3 WU m3 Lind U 20mV 500 5 Ch2 7 59 6 D 5ps Figure 3 4 Altitude Coded Pulses 190 00133 02 Rev B 3 9 3 3 3 11 IDENT Test 1 Set the ATC 1400A to Mode A 2 Turn the GTX 320 mode select knob to the ON position 3 Set the RF level on the ATC 1400A for a 100 reply rate 4 Press the IDENT button on the transponder The unit shall cause the 1400 XPDR Code display to read 1d0000 for approximately 20 seconds The SPI pulse shall appear next to the P3 pulse on the oscilloscope See Figure 3 5 5 Rotate the mode select switch to the SBY position 6 Press the IDENT button on the transponder The reply light shall turn on for approximately 25 seconds but the unit shall not transmit OK 1 1
18. table substitute is used to adjust the transmitter frequency 1 Transponder DME Test Set IFR Systems ATC 1400A 2 Power Supply Topward 2000 3 Digital Oscilloscope Tek TDS 320 or suitable equivalent 4 Voltmeter Fluke 79 5 50 Ohm Load ITT Pomona Model 3840 50 6 Transmitter Adjustment Tool Locally Made see Figure 2 1 7 Rack Mount BNC to BNC Cable RG 58 U having a total cable loss of 1 5 dB at 1090 MHz 3 2 2 Alignment Setup Figure 2 3 shows a typical alignment and test setup based on the I O of the 25 pin connector J102 and the rear antenna connector J103 Use the 28 VDC input during alignment 3 2 3 Alignment Procedure CAUTION Use extreme care when adjusting C620 so that the transmitter is NOT allowed to oscillate at frequencies below 1080 MHz and risk damaging the mixer A failed mixer cannot be replaced in the field the unit must be returned to GARMIN for repair A failed mixer will degrade MTL by several dB 190 00133 02 Rev B 3 1 1 Carefully dislodge the thin metal piece that covers the access holes to the transmitter section figure 3 1 by prying one end with a small thin screwdriver 2 Set the ATC1400A front panel controls to the following PARAMETER SET POINT XPDR MODE MODE C PRF 500 Hz RF LEVEL 50 dBm SLS ECHO OFF FREQUENCY POWER TOGGLE SWITCH F P OK 3 Set the GTX320 transponder mode select control knob to the ON position OK NOTE Allow the u
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