Volume 1
MIL-HDBK-162A
Section 1
15 December 1965
ITEM NAME: INTERROGATOR SET, RADIO
TYPE: AN/GPX-20A
Transmitting Frequency: 990 to 1040 mc
The equipment permits the video pulses to be displayed
Receiving Frequency: 1080 to 1130 mc
on the PPI indicators of the associated radar set to
Peak Power Output: 1.5 kw (min)
supplies the video pulses to SIF Coder-Decoder Group
Pulse Width: 1 usec
OA-842/ GPX-20A. The OA-842/GPX-20A supplies
Pulse Repetition Rate: 180 to 420 pps (adjusted
coded pulses for security identity, personnel identity,
to conform with prr of associated radar)
and traffic identity. The set decodes multiple-pulse
Number of Modes: 3
response codes transmitted by airborne equipment in
Number of Codes: 32 SI, 400 PI, 64 TI
reply to interrogations or challenges and supplies the
Range: Range of associated radar
video signals to the indicators of the associated radar.
Antenna: Dipole (24 radiating slots)
The interrogator output and the receiver sensitivity are
Beam Width: 4.5 deg horiz; 30 deg vert
adequate for interrogating and receiving replies from
Receiver Bandwidth: 8 to 11 mc at 6 db down,
transponders operating within the detection range of the
narrow; 5 mc at 70 db down, broad
associated radar.
The AN/GPX-20A may be
Type of Presentation:
PPI indicators of
independently operated to track targets equipped with
associated radar
radar identification set.
Receiver Intermediate Frequency: 60 mc
Operating Voltages and Power Requirements:
RELATION TO SIMILAR EQUIPMENT:
115v ac, 45 to 70 cps, 1-ph, 4 kw
Similar to and one-way interchangeable with
AN/GPX-20. Differs in that the AN/GPX-20A utilizes
INSTALLATION CONSIDERATIONS:
Coder-Decoder Group OA-842/GPX-20A for selective
Siting: Physically located with associated radar.
identification feature (SIF) and AN/GPX-20 does not.
Mounting: Mounted on basic radar set.
AN/GPX-20A is similar to and interchangeable
Related Equipment: Radar Set AN/MPS-7 and
with AN/GPX-20B, differs in type of Coder-Decoder
other models.
Group used.
TECHNICAL DESCRIPTION
PRINCIPAL COMPONENTS AND PHYSICAL DATA
COMPONENT
QTY
HEIGHT
WIDTH
DEPTH
UNIT WT.
(Inches)
(Inches)
(Inches)
(Pounds)
Video Decoder KY-118/GPX
7
28-3/16
18
13
161
Video Decoder KY-119/GPX
2
28-3/16
18
13
96
Interrogator Set Group
1
28-3/16
18
13
121
KY-120/GPX
Electronic Gate TD-94/GPX
1
28-3/16
18
13
93
Coder Control C-2364/GPX
1
6-3/16
6-3/16
6-7/16
4
Remote Switching Control
6
6-3/16
6-3/16
6-15/16
4
C-1289/GPX
Remote Switching Control
6
6
6-3/16
6-3/4
3
C-2365/GPX
Electrical Frequency Control
1
8
17
6
2
C-2028/GPX
Interconnecting Box J-664/GPX
2
3
13-1/16
7-1/8
5.5
Mounting MT-1501/GPX
6
18-1/2
19-13/16
13/16
6
Electrical Equipment Rack
6
73-5/8
18-3/8
30
132
NT-1502/GPX
Installation Safety Switch
1
15-3/16
10-1/2
7-1/8
19
AN/GPX-20A: 2
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