ISCET RADAR EXAM UPDATED
QUESTIONS AND CORRECT ANSWERS.
To install and maintain a RADAR, you must have: - ANS GROL w/ Radar or GMDSSIM w/
Radar
Who may replace fuses and receiving type tubes and circuits in a Radar? - ANS Holder of
GROL w/ Radar
Under what circumstances can an unlicensed person operate a radar set? - ANS Only if the Tx
is a non-tunable type and when the master of the ship designated him to operate it
What Radar maintenance work may be done by unlicensed workers? - ANS None
Who is permitted to operate a ship Radar? - ANS Master of the ship, or anyone designated
by the master.
What is box 46 of EL8-A? - ANS TR Box
What is box 47 of EL8-A? - ANS RF Attenuator
What is box 48 of EL8-A? - ANS Klystron
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
,What is box 49 of EL8-A? - ANS Crystal Detector
What is box 50 of EL8-A? - ANS Discriminator
The minimum range of a Radar is primarily determined by: - ANS The pulse width and TR
(TRL) cell recovery time
An RF mixer has what purpose in a Radar system? - ANS It converts low-level signal to a
different frequency
The switching devices most commonly used in pulse networks, and pulse transformers are/is: -
ANS SCR's and Thyratrons
Good bearing resolution largely depends upon: - ANS A narrow antenna beam in the
horizontal plane
Bearing Resolution is: - ANS The ability to distinguish two adjacent targets of equal distance.
An artificial line is used for: - ANS Determining the shape and durations of the pulses
What device is located between the magnetron and the mixer and prevents received signals
from entering the magnetron? - ANS The ATR box
The ATR Box: - ANS Prevents the received signal from entering the transmitter
When a pulse radar is radiating, which elements in the TR box are energized? - ANS The TR
and ATR tubes
In the AFC system, the discriminator compares the frequencies of the: - ANS Magnetron and
Klystron
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, The purpose of the discriminator circuit in a Radar is to: - ANS Generate a corrective voltage
for controlling the frequency of the klystron local oscillator
Where is the RF Attenuator used in a Radar? - ANS Between the Magnetron and AFC section
of the receiver
What frequency is the discriminator tuned to? - ANS 30 MHz IF
The usual intermediate frequency of a shipboard Radar unit is: - ANS 30 or 60 MHz
The error voltage from the discriminator us applied to: - ANS The repeller (reflector) of the
klystron
How may the frequency of the klystron be varied? - ANS Small changes can be made by
adjusting the repeller voltage and large changes can be made by adjusting the size of the
resonant cavity
Fine adjustment of the reflex klystron are accomplished by: - ANS Varing the repeller voltage
The pulse repetition rate (PRR) refers to: - ANS The pulse rate of the magnetron
The timer circuit: - ANS Determines the PRR, determines range markers, and provides
blanking and unblanking signals for the CRT
On what frequency is radar expected to cause interference? - ANS On most any
communication frequency
If the magnetron is allowed to operate without the magnetic field in place: - ANS It will
quickly destroy itself from excessive current flow
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
QUESTIONS AND CORRECT ANSWERS.
To install and maintain a RADAR, you must have: - ANS GROL w/ Radar or GMDSSIM w/
Radar
Who may replace fuses and receiving type tubes and circuits in a Radar? - ANS Holder of
GROL w/ Radar
Under what circumstances can an unlicensed person operate a radar set? - ANS Only if the Tx
is a non-tunable type and when the master of the ship designated him to operate it
What Radar maintenance work may be done by unlicensed workers? - ANS None
Who is permitted to operate a ship Radar? - ANS Master of the ship, or anyone designated
by the master.
What is box 46 of EL8-A? - ANS TR Box
What is box 47 of EL8-A? - ANS RF Attenuator
What is box 48 of EL8-A? - ANS Klystron
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
,What is box 49 of EL8-A? - ANS Crystal Detector
What is box 50 of EL8-A? - ANS Discriminator
The minimum range of a Radar is primarily determined by: - ANS The pulse width and TR
(TRL) cell recovery time
An RF mixer has what purpose in a Radar system? - ANS It converts low-level signal to a
different frequency
The switching devices most commonly used in pulse networks, and pulse transformers are/is: -
ANS SCR's and Thyratrons
Good bearing resolution largely depends upon: - ANS A narrow antenna beam in the
horizontal plane
Bearing Resolution is: - ANS The ability to distinguish two adjacent targets of equal distance.
An artificial line is used for: - ANS Determining the shape and durations of the pulses
What device is located between the magnetron and the mixer and prevents received signals
from entering the magnetron? - ANS The ATR box
The ATR Box: - ANS Prevents the received signal from entering the transmitter
When a pulse radar is radiating, which elements in the TR box are energized? - ANS The TR
and ATR tubes
In the AFC system, the discriminator compares the frequencies of the: - ANS Magnetron and
Klystron
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, The purpose of the discriminator circuit in a Radar is to: - ANS Generate a corrective voltage
for controlling the frequency of the klystron local oscillator
Where is the RF Attenuator used in a Radar? - ANS Between the Magnetron and AFC section
of the receiver
What frequency is the discriminator tuned to? - ANS 30 MHz IF
The usual intermediate frequency of a shipboard Radar unit is: - ANS 30 or 60 MHz
The error voltage from the discriminator us applied to: - ANS The repeller (reflector) of the
klystron
How may the frequency of the klystron be varied? - ANS Small changes can be made by
adjusting the repeller voltage and large changes can be made by adjusting the size of the
resonant cavity
Fine adjustment of the reflex klystron are accomplished by: - ANS Varing the repeller voltage
The pulse repetition rate (PRR) refers to: - ANS The pulse rate of the magnetron
The timer circuit: - ANS Determines the PRR, determines range markers, and provides
blanking and unblanking signals for the CRT
On what frequency is radar expected to cause interference? - ANS On most any
communication frequency
If the magnetron is allowed to operate without the magnetic field in place: - ANS It will
quickly destroy itself from excessive current flow
3 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
