Narco AT-150 Transponder

Installation and Inspection

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2.1 Introduction

This section provides the necessary information for the Installation of the AT 150 TSO and, where required, optional accessories. The mechanical and electrical sections are self-supporting and may be removed from the manual to permit the mechanical and electrical installation efforts to proceed simultaneously.

2.2 Preliminary Inspection

2.2.1 Unpacking

Carefully unpack the Unit and inspect it for any damage that may have occurred during shipment. Refer to Section 1.5, Units and Accessories Supplied, and inventory the contents of the Installation Kit. Refer to Section 1.7, Miscellaneous Items Required but NOT Supplied for a listing of items and equipment needed for proper installation.

2.2.2 Electrical Bench Test

2.2.2.1 Test Equipment Required
  1. Transponder and DME Test Set: IFR Model ATC-600A or equivalent.
  2. 34 dB attenuation pad.
2.2.2.2 Test Procedure

A. Set-Up

  1. The AT 150 should be tested while contained in the mounting tray with the RF cable installed.
  2. When the AT 150 is being interrogated by the ATC-600A, the IDENT/DIM button will blink ON and OFF.

B. Receiver Sensitivity

  1. Place the AT 150 in the ON mode. Place the ATC-600A in the A/C CODE mode.
  2. Rotate the ATC-600A XPDR SIG level control full counterclockwise. The % scale of the XPDR RPLY meter should read 100%.
  3. Rotate the XPDR SIG level control clockwise until the XPDR RPLY meter reads 90%.
  4. The XPDR SIG level control indicator should be between -69 and -73 dBm. This is the MTL of the transponder.
  5. Repeat steps 2, 3, and 4 with the AT 150 In the ALT mode and the ATC-600A in the A/C ALT mode. The difference between the MTL readings should not be greater than 1 dBm.

C. SLS (Side-Lobe Suppression)

  1. Place the AT 150 in the ON mode. Place the ATC-600A In the A/C CODE mode.
  2. Rotate the XPDR SIG level control full counterclockwise. The XPDR RPLY meter should read 100%.
  3. Set the XPDR SIG level control to 3 dB above MTL (level established in step B-4).
  4. Set the SI.S swItch to 0 dB. The XPDR RPLY meter should read zero.
  5. Set the SI.S switch to 9 dB: The XPDR RPLY meter should read 90% minimum.

D. Code Selection

  1. Place the AT 150 in the ON mode. Place the ATC-600A to the A/C CODE mode.
  2. The ATC-600A numerical display should display the code selected by, the AT 150 Code Selector switches. Several different codes should be selected.
  3. Consider the AT 150 Code Selector switches to be labeled A, B, C, and D. Switch A should light the ATC-600A Binary Readout lamp Al when it is in the 1 position, the A lamp in the 2 position, and the A1 and A2 lamps in the 3 position. In each twitch position, the sum of the subscripts of the Binary Readout lamps that light should equal the number selected.
  4. Repeat the above procedure for switches B, C, and D.

E. Transmitter Frequency

  1. Place the AT 150 in the ON mode and set the Code Selector switches to 0000.
  2. Place the ATC-600A In the A/C CODE mode and set the POWER/FREQ switch to FREQ.
  3. Adjust the GAIN control for a mid-scale reading on the POWER meter.
  4. Rotate the XMTR FREQ control for a peak Indication on the POWER meter.
  5. At peak, read the deviation from 1090 MHz directly from the XMTR FREQ control dial. The deviation should be no greater than 3 MHz.

F. Transmitter Power

  1. Place the AT 150 in the ON mode and set the Code Selector switches to 6050.
  2. Place the ATC-600A in the A/C CODE mode and set the POWER/FREQ switch to POWER.
  3. Read 125 watts on the POWER meter .

G. IDENT

  1. Place the AT 150 in the ON mode. Place the ATC-600A in the A/C CODE mode.
  2. Momentarily depress the IDENT/DIM button on the AT 150.
  3. The AT 150 IDENT/DIM button and the ATC-600A IDENT lamp should glow for approximately 20 5 seconds.

H. Altitude Digitizer Inputs

The following procedure is a functional check of the Altitude Digitizer Inputs P101-6 through P101-14 only. Therefore, the numerical readout and INVALID ALT lamp on the ATC-600A should be ignored.

  1. Place the AT 150 in the ALT mode. Place the ATC-600A in the A/C ALT mode.
  2. Placing an Altitude Digitizer Input at ground potential will activate a corresponding Binary Readout lamp on the ATC-600A. Table 2.1 lists the P101 pin numbers and their corresponding ATC-600A Binary Readout lamps.
Ground - P101 Activate ATC-600A Binary Readout Lamp
6 A2
7 A1
8 A4
9 B4
10 B2
11 C2
12 B1
13 C4
14 C1

    Table 2-1 - Altitude Digitizer Inputs

I. Disconnect the transponder from the Test Set-Up.

 
     
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