nzart-exam-generator/files/N29.TXT

% FILENAME = N29.TXT
% Interference and Filtering 
% Release version 4, June 2004

%QUESTION: 1 
#29.1 Electromagnetic compatibility is: 

two antennas facing each other 

the ability of equipment to function satisfactorily in its own environment without introducing intolerable electromagnetic disturbances

more than one relay solenoid operating simultaneously 

the inability of equipment to function satisfactorily together and produce tolerable electromagnetic disturbances 

% ans 2

%QUESTION: 2 
#29.2 On an amateur receiver, unwanted signals are found at every 15.625 kHz. This is probably due to: 

a low-frequency government station 

a remote radar station 

radiation from a nearby TV line oscillator 

none of these 

% ans 3

%QUESTION: 3 
#29.3 Narrow-band interference can be caused by: 

transmitter harmonics 

a neon sign 

a shaver motor 

lightning flashes 

% ans 1

%QUESTION: 4 
#29.4 Which of the following is most likely to cause broad-band continuous interference: 

an electric blanket switch 

a refrigerator thermostat 

a microwave transmitter 

poor commutation in an electric motor 

% ans 4

%QUESTION: 5 
#29.5 If broadband noise interference varies when it rains, the most likely cause could be from: 

underground power cables  

outside overhead power lines  

car ignitions  

your antenna connection  

% ans 2

%QUESTION: 6 
#29.6 Before explaining to a neighbour that the reported interference is due to a lack of immunity in the neighbour's electronic equipment: 

disconnect all your equipment from their power sources 

write a letter to the MED 

make sure that there is no interference on your own domestic equipment 

ignore all complaints and take no action 

% ans 3

%QUESTION: 7 
#29.7 A neighbour's stereo system is suffering RF break-through. One possible cure is to: 

put a ferrite bead on the transmitter output lead 

put a capacitor across the transmitter output 

use open-wire feeders to the antenna 

use screened wire for the loudspeaker leads 

% ans 4

%QUESTION: 8 
#29.8 When living in a densely-populated area, it is wise to: 

always use maximum transmitter output power 

use the minimum transmitter output power necessary 

only transmit during popular television programme times 

point the beam at the maximum number of television antennas 

% ans 2

%QUESTION: 9 
#29.9 When someone in the neighbourhood complains of TVI it is wise to: 

deny all responsibility 

immediately blame the other equipment 

inform all the other neighbours 

check your log to see if it coincides with your transmissions 

% ans 4

%QUESTION: 10 
#29.10 Cross-modulation is usually caused by: 

rectification of strong signals in overloaded stages 

key-clicks generated at the transmitter 

improper filtering in the transmitter 

lack of receiver sensitivity and selectivity 

% ans 1

%QUESTION: 11 
#29.11 When the signal from a transmitter overloads the audio stages of a broadcast receiver, the transmitted signal: 

can be heard irrespective of where the receiver is tuned 

appears only when a broadcast station is received 

is distorted on voice peaks 

appears on only one frequency 

% ans 1

%QUESTION: 12 
#29.12 Cross-modulation of a broadcast receiver by a nearby transmitter would be noticed in the receiver as: 

a lack of signals being received 

the undesired signal in the background of the desired signal 

interference only when a broadcast signal is received 

distortion on transmitted voice peaks 

% ans 2

%QUESTION: 13 
#29.13 Unwanted signals from a radio transmitter which cause harmful interference to other users are known as: 

rectified signals 

re-radiation signals 

reflected signals 

harmonic and other spurious signals 

% ans 4

%QUESTION: 14 
#29.14 To reduce harmonic output from a transmitter, the following could be put in the transmission line as close to the 
transmitter as possible: 

wave trap 

low-pass filter 

high-pass filter 

band reject filter 

% ans 2

%QUESTION: 15 
#29.15 To reduce energy from an HF transmitter getting into a television receiver, the following could be placed in the TV antenna lead as close to the TV as possible: 

active filter 

low-pass filter 

high-pass filter 

band reject filter 

% ans 3

%QUESTION: 16 
#29.16 A low-pass filter used to eliminate the radiation of unwanted signals is connected to the: 

output of the balanced modulator 

output of the amateur transmitter 

input of the stereo system 

input of the mixer stage of your SSB transmitter 

% ans 2

%QUESTION: 17 
#29.17 A band-pass filter will: 

pass frequencies each side of a band 

attenuate low frequencies but not high frequencies 

attenuate frequencies each side of a band 

attenuate high frequencies but not low frequencies 

% ans 3

%QUESTION: 18 
#29.18 A band-stop filter will: 

pass frequencies each side of a band 

stop frequencies each side of a band 

only allow one spot frequency through 

pass frequencies below 100 MHz 

% ans 1

%QUESTION: 19 
#29.19 A low-pass filter for a high frequency transmitter output would: 

attenuate frequencies above 30 MHz 

pass audio frequencies below 3 kHz 

attenuate frequencies below 30 MHz 

pass audio frequencies above 3 kHz 

% ans 1

%QUESTION: 20 
#29.20 Installing a low-pass filter between the transmitter and transmission line will: 

permit higher frequency signals to pass to the antenna 

ensure an SWR not exceeding 2:1 

reduce the power output back to the legal maximum 

permit lower frequency signals to pass to the antenna 

% ans 4

%QUESTION: 21 
#29.21 A low-pass filter may be used in an amateur radio installation: 

to attenuate signals lower in frequency than the transmission 

to attenuate signals higher in frequency than the transmission 

to boost the output power of the lower frequency transmissions 

to boost the power of higher frequency transmissions 

% ans 2

%QUESTION: 22 
#29.22 Television interference caused by harmonics radiated from an amateur transmitter could be eliminated by fitting: 

a low-pass filter in the TV receiver antenna input 

a high-pass filter in the transmitter output 

a low-pass filter in the transmitter output 

a band-pass filter to the speech amplifier 

% ans 3

%QUESTION: 23 
#29.23 A high-pass filter can be used to: 

prevent interference to a telephone 

prevent overmodulation in a transmitter 

prevent interference to a TV receiver 

pass a band of speech frequencies in a modulator 

% ans 3

%QUESTION: 24 
#29.24 A high-pass RF filter would normally be fitted: 

between transmitter output and feedline 

at the antenna terminals of a TV receiver 

at the Morse key or keying relay in a transmitter 

between microphone and speech amplifier 

% ans 2

%QUESTION: 25 
#29.25 A high-pass filter attenuates: 

a band of frequencies in the VHF region 

all except a band of VHF frequencies 

high frequencies but not low frequencies 

low frequencies but not high frequencies

% ans 4

%QUESTION: 26 
#29.26 An operational amplifier connected as a filter always utilises: 

positive feedback to reduce oscillation 

negative feedback 

random feedback 

inductors and resistor circuits only 

% ans 2

%QUESTION: 27 
#29.27 The voltage gain of an operational amplifier at low frequencies is: 

very high but purposely reduced using circuit components 

very low but purposely increased using circuit components 

less than one 

undefined 

% ans 1

%QUESTION: 28 
#29.28 The input impedance of an operational amplifier is generally: 

very high 

very low 

capacitive 

inductive 

% ans 1

%QUESTION: 29 
#29.29 An active audio low-pass filter could be constructed using: 

zener diodes and resistors 

electrolytic capacitors and resistors 

an operational amplifier, resistors and capacitors 

a transformer and capacitors 

% ans 3

%QUESTION: 30 
#29.30 A filter used to attenuate a very narrow band of frequencies centred on 3.6 MHz would be called: 

a band-pass filter 

a high-pass filter 

a low-pass filter 

a notch filter 

% ans 4