from pinoy bix amplifiers Flashcards
which of the following is (are) power amplifiers
a. class a
b. class B or AB
c. class c or d
d. all of the above
all of the above
by how much does the output signal signal vary for a class AB power amplifier
between 180• and 360•
which type of amplifier is biased for operation at less that 180• of the cycle
Class C
which type of amplifier uses pulse digital signals in its operation
class D
which of the power amplifiers has the lowest overall efficiency
Class A
which of the following describes a power amplifier
a. it can handle large power
b. it can handle large current
c. it does not provide much voltage gain
d. all of the above
all of the above
amplifiers primarily provide sufficient power to an output load to drive a speaker from few watts to ten watts
power
the main features of a large signal amplifier is the circuit’s
a. power efficiency
b. maximum power limitations
c. impedance matching to the output device
d. all of the above
all of the above
Class AB operation is _____ operation
a. similar to class a
b. similar to class b
c. similar to class c
d. none of the above
none of the above
which operation class is generally used in radio or communications
Class D
Categorieze the power efficiency of each class of amplifier from worst to best
A,AB,B,D
what is the maximum efficiency of a Class A circuit with a direct or series fed load connection?
25%
what is the ratio of the secondary voltate to the primary voltage with the turn ratio in the winding?
N2/N1
the maximum efficiency of a transformer coupled class a amplifier
50%
what is the maximum efficiency of a class B circuit?
78.5%
how many transistors must be used in a class b power amplifier to obtain the output for the full cycle of the signal
2
Class B operation is provided when dc bias leaves the transistor biased just off, the transistor turning on when the ac signal is applied (true/false)
true
which of the push pull amplifierd is presently the most popular form of the class b power
Quasi Complementary
which of the following instruments displays the harmonic of a distorted signal
spectrum analyzer
which of the folloeing instrument allows more precise measurement of the harmonic components of a distorted signal
wave analyzer
maximum temp. rating for silicon power transistors
150• to 200•
which power amplifier is not intended primarily for large signal or power amplification
Class C
popular transistor driver device for class D amplification
MOSFET
amplifier that has an output signal varies for a full 360 degrees of the cycle
class A
Class B amplifieroutput signal varies of the cycle
180•
highest overall efficiency amplifier
Class D
Class D operation can achieve power efficiency of over
90%
the beta of a power transistor is generally
less than 100
First active satellite
Sputnik I
First commercial satellite
Telstar
first passive satellite transponder?
early bird
First satellite to receive and transmit simultaneously
Telstar I
A helical antenna is used for satellite tracking because of
circular polarization
repeaters inside communications satellite are known as
Transponders
considered unsolved problem in satellite system
privacy
geographical representation of a satellite antenna radiation
footprint
smallest beam of a satellite antenna radiation pattern
spot beam
a satellite beam that covers almost 42.4% of the earths surface
global beam
frequency range of C band
3.4 to 6.45 GHz
a satellite signal transmitted from a satellite transponder to earth station
Downlink
collects a very weak signal from broadcast satellite
Satellite Dish
detects the satellite signal relayed from the feed and converts it to an electric current amplifies and lowers its frequency
LNA
loss of power of a satellite downlink signal due to earth’s atmosphere
path loss
what height must a satellite be placed above the surface of the earth in order for its rotation?
22,426.4 miles
point on the satellite orbits closest to the earth
perigee
earth area covered by a satellite radio beam
foot print
what is the local oscillator frequency of the satellite with an uplink frequency in GHz band
2225 MHz
vsat was made available in
1979
what band does vsat first operate
C band
First Philippine Mabuhay satellite has how many channels
30
The first philippine agila I will have how many transponder
36
approximate path loss from satellite to earth station
200 dB
INTELSAT
International Telecommunications Satellite
a satellite cross link means
satellite to satellite link
delay time for satellite transmission from earth transmitter to earth receiver
0.5 s
as the height of a satellit3 orbit gets lower. the speed of the satellite
increases
