Unit 5-2

Front 1

(808) What is the original source of the continuous wave (CW) transmitter drive?

Back 1

37-MHz crystal oscillator.

Front 2

(808) The transmitted pulse is made of two .5-microsecond pulses, separated in frequency by...

Back 2

37 MHz

Front 3

(809) The stabilized master oscillator multiplies the continuous wave transmitter drive signal to...

Back 3

X-band

Front 4

(809) How long is the traveling wave tube (TWT) turned on to amplify the transmitted RF pulse?

Back 4

1.35 usec

Front 5

(809) The purpose of the traveling wave tube (TWT) radar modulator in the transmitter is to...

Back 5

provide voltage amplification and trigger shaping for the TWT.

Front 6

(809) In the AN/GPN-22 transmitter, which fault would cycle the transmitter to the STANDBY mode of operation?

a. Traveling wave tube (TWT) arc.
b. High voltage (HV) deck fault.
c. Standby converter fault.
d. Airflow fault.

Back 6

a. Traveling wave tube (TWT) arc.

Front 7

(810) The principle purpose of the antenna beam position unit (ABPCU) and array phase control unit (APCU) in the AN/GPN-22 is to...

Back 7

generate phase delay commands to phase shifter elements of the antenna.

Front 8

(810) The 443 memory constants for each beam position are sent to the phase computation algorithm and converted into phase commands containing how many bits?

Back 8

3

Front 9

(810) Which of the following is an off-line test preformed on the antenna position control unit?

a. Mode control
b. Open loop
c. Closed loop
d. Rebound Test

Back 9

d. Rebound test

Front 10

(811) The AN/GPN-22 precision approach radar's transmit/receive (T/R) section does what?

Back 10

It prevents receiver damage by the transmitter high-power pulse during transmission.

Front 11

(811) The best description of sensitivity time control (STC) attenuators is they...

Back 11

automatically adjust receiver sensitivity in the discrete normalizing target return energy depending on range.

Front 12

(811) The sensitivity timing control (STC) assures constant amplitude intermediate frequency (IF) signal to the receiver by...

Back 12

providing high attenuation for near targets (which produce strong signals) and gradually less attenuation for distant targets.

Front 13

(811) In the AN/GPN-22 precision approach radar, the total multiplication factor used by the stabilized oscillator (STALO) to achieve an X-band frequency is?

Back 13

X48

Front 14

[808] Why is the TWT used in the AN/GPN-22 instead of a magnetron?

Back 14

The TWT provides high amplification over a wide range of frequencies, which is something a magnetron cannot do.

Front 15

[808] Describe how the TWT amplifies an RF signal.

Back 15

The TWT amplives through the bunching of electrons in an electron stream interacting with the RF signal energy on a helix, with each causing amplification in the other.

Front 16

[808] The STAMO is a frequency multiplier that multiplies the input VHF drive signal by what factor?

Back 16

48

Front 17

[808] Why use contiguous pulses?

Back 17

To provide frequency diversity.

Front 18

[809] How many transmitter(s) can radiate into the antenna at a time?

Back 18

Only one at a time

Front 19

[809] Which LED on the front panel of the low power transmitter monitors the input VHF signal?

Back 19

The "TWT RF INP" LED

Front 20

[809] What determines the amount of RF drive applied to the TWT?

Back 20

The setting of attenuator AT1

Front 21

[809] What is the purpose of the TWT Modulator A6?

Back 21

It is a pulse shaper and voltage amplifier. It contains a regulator and clamp circuit that produces a flat-topped output pulse that is used to turn on the TWT.

Front 22

[809] Define a 3X fault.

Back 22

A condition that may cause damage if it is allowed to persist or reoccur in rapid succession.

Front 23

[809] If a standby fault occurs, the transmitter cycles to what mode?

Back 23

OFF mode

Front 24

[809] List the events that take place during a 3X fault.

Back 24

First the HVPS shuts down temporarily, then a second time, then shuts down completely. The system must be reset manually. An indicator points out which fault caused the condition.

Front 25

[810] Name the units that make up the antenna beam position control equipment and the location of each unit.

Back 25

The Antenna Beam Position Control Unit (ABPCU) located in an equipment rack in the PAR shelter and the Array Phase Control Unit (APCU), located in the antenna assembly.

Front 26

[810] State the principal function of the interface equipment.

Back 26

To generate appropriate phase commands to each of 443 phase-shifter elements of the antenna.

Front 27

[810] Where are the control signals and the antenna beam positoin commands from the TDC routed?

Back 27

To interface control circuits and TDC command data register logic respectivly.

Front 28

[810] In scan mode the beam can be directed into how many separate beam positions?

Back 28

439

Front 29

[810] What are the two methods for testing the ABPCU and APCU?

Back 29

Off-line tests and On-line tests

Front 30

[810] How can the inputs from the TDC be duplicated during the off-line testing?

Back 30

By the use of the ABPCU front panel controls.

Front 31

[810] Which off-line test analyzes the communication lines between the Antenna Beam Postion Control Unit (ABPCU) and the Antenna Phase Control Unit (APCU)?

Back 31

Rebound Test

Front 32

[810] What is the purpose of the Shift Register test?

Back 32

It analyses each shift register and the associated parallel data input lines, and reveals faulty block decodes.

Front 33

[811] What is the purpose of the high-power ferrite circulator 1A40A1A2HY1?

Back 33

The duplexer directs the RF from the transmitter to the antenna horn for transmission and directs the received sum channel RF energy to the receiver sum channel.

Front 34

[811] List the parts of a reciever-protector.

Back 34

Pretransmitt/Receive, STC, and two diode RF attenuators

Front 35

[811] What is the condition of the STC attenuators just before transmitter firing a radar pulse?

Back 35

All attenuators are switched in to provide maximum attenuation.

Front 36

[811] What channel contains the FET amplifier?

Back 36

The sum channel

Front 37

[811] What is the multiplication factor in the reciever front-end STALO?

Back 37

48

Front 38

[811] In what mode of operation does the sum channel FET amplifier get bypassed?

Back 38

Track mode

Front 39

[811] What is the purpose of the UHF preamplifier?

Back 39

The UHF amplifier-mixer provides RF-to-IF conversion, low-noise amplification, and IF image rejection for the sum, azimuth difference, and elevation difference signals.

Front 40

[811] What is the final result caused by the negative pretrigger pulse to the STC circuit located in the UHF preamplifier?

Back 40

It switches in the IF attenuators.

Front 41

[811] At what increments are the attenuators stepped down as range increases?

Back 41

10 dB steps

Front 42

[811] Where does the receiver frount-end BITE signal originate?

Back 42

In the transmitter, a sample of the RF drive signal is picked off from the signal chain at a point proir to the TWT.