T4B Electrical wiring, including switch
location, dangerous voltages
and
currents; SWR meaning and measurements; SWR meters
T4B01
@T4A01
Where
should the green wire in a three-wire AC line cord be connected
in a
power supply?
A. To the fuse
B. To the "hot" side of the power
switch
C. To the chassis
D. To the white wire
T4B02
@T4A10
What is
the minimum voltage that is usually dangerous to humans?
A. 30 volts
B. 100 volts
C. 1000 volts
D. 2000 volts
T4B03
@T4A14
How
much electrical current flowing through the human body will
probably
be fatal?
A. As little as 1/10 of an ampere
B. Approximately 10 amperes
C. More than 20 amperes
D. Current through the human body is never
fatal
T4B04
@T4A15
Which
body organ can be fatally affected by a very small amount of
electrical
current?
A. The heart
B. The brain
C. The liver
D. The lungs
T4B05
@N4C02
What
does an SWR reading of less than 1.5:1 mean?
A. An impedance match that is too low
B. An impedance mismatch; something may be
wrong with the antenna
system
C. A fairly good impedance match
D. An antenna gain of 1.5
T4B06
@N4C05
What
does a very high SWR reading mean?
A. The antenna is the wrong length, or there
may be an open or
shorted
connection somewhere in the feed line
B. The signals coming from the antenna are
unusually strong, which
means
very good radio conditions
C. The transmitter is putting out more power
than normal, showing
that it
is about to go bad
D. There is a large amount of solar radiation,
which means very poor
radio
conditions
T4B07
@N4C06
If an
SWR reading at the low frequency end of an amateur band is
2.5:1,
increasing to 5:1 at the high frequency end of the same band,
what
does this tell you about your 1/2-wavelength dipole antenna?
A. The antenna is broadbanded
B. The antenna is too long for operation on the
band
C. The antenna is too short for operation on
the band
D. The antenna is just right for operation on
the band
T4B08
@N4C07
If an
SWR reading at the low frequency end of an amateur band is 5:1,
decreasing
to 2.5:1 at the high frequency end of the same band, what
does
this tell you about your 1/2-wavelength dipole antenna?
A. The antenna is broadbanded
B. The antenna is too long for operation on the
band
C. The antenna is too short for operation on
the band
D. The antenna is just right for operation on
the band
T4B09
@N4C10
What
instrument is used to measure the relative impedance match
between
an antenna and its feed line?
A. An ammeter
B. An ohmmeter
C. A voltmeter
D. An SWR meter
T4B10
@T4C09
If you
use an SWR meter designed to operate on 3-30 MHz for VHF
measurements,
how accurate will its readings be?
A. They will not be accurate
B. They will be accurate enough to get by
C. If it properly calibrates to full scale in
the set position, they
may be
accurate
D. They will be accurate providing the readings
are multiplied by 4.5
T4B11
@N4C01
What
does an SWR reading of 1:1 mean?
A. An antenna for another frequency band is
probably connected
B. The best impedance match has been attained
C. No power is going to the antenna
D. The SWR meter is broken