FM (frequency modulated) radio
certainly was a hot topic beginning in the middle to late 1940s. With the war out
of the way, energies and resources were being redirected back to peacetime production.
Major Edwin Armstrong announced his FM scheme in 1935, and as with many new
inventions, it was met with skepticism by many who doubted his claim of static interference
immunity. For many, it was a lack of understanding that caused the negative reaction,
caused primarily by the increased level of sophistication of the transmitter and
receiver circuitry. Amplitude modulation (AM) was so
easy even a caveman could
understand it, but adding phase relationships into the equation (literally)
left many in the dust. This FM Radio Quiz from a 1950 issue of Radio & Television
News magazine tests your grasp of frequency modulation principles.
By Ed Bukstein
Northwestern Vocational Institute
1. On the commercial FM channels (88 to 108 mc.) , one hundred per-cent modulation
is defined as a frequency deviation of plus and minus (a) 88 kc. (b) 21.75 kc. (c)
75 kc. (d) 25 kc.
2. If a commercial FM station produces a signal whose deviation is plus and minus
60 kc., its percentage of modulation is (a) 20% (b) 60% (c) 80% (d) 100%.
3. The rate at which the FM signal swings back and forth is deter-mined by the
(a) amplitude of the audio signal (b) frequency of the audio signal (c) height of
the antenna (d) effective radiated power.
4. The deviation of an FM signal increases when the amplitude of the audio signal
(a) increases (b) decreases.
5. If a 30 kc. deviation is produced by a 5000 cycle audio signal, the modulation
index is (a) 150 (b) 25,000 (c) 0.16 (d) 6.
6. The ratio of the maximum frequency deviation to the highest audio modulating
frequency is called the (a) aspect ratio (b) deviation ratio (c) ratio detector.
7. If an FM signal having a deviation of plus and minus 2 kc. is fed successively
through a frequency doubler and a frequency quadrupler, the output signal will have
a frequency deviation of plus and minus (a) 6 kc. (b) 8 kc. (c) 16 kc. (d) 32 kc.
8. The circuit designed to remove any undesirable amplitude modulation from a
frequency modulated signal is known as a (a) limiter (b) reactance modulator (c)
9. In the circuit shown in Fig. 1, tube V, is a (a) reactance modulator (b) d.c.
restorer (c) ratio detector (d) Wien bridge.
10. Tube V1 of Fig. 1 behaves like (a) an inductance (b) a condenser.
11. The second detector of an FM receiver is more properly known as a (a) frequency
modulator (b) frequency divider (c) frequency multiplier (d) discriminator.
12. The circuit shown in Fig. 2 is a (a) pre-emphasis filter (b) high-pass filter
(c) de-emphasis filter.
13. As specified by the FCC, the pre-emphasis filter should have a time constant
of (a) 25 (b) 75 (c) 500 (d) 10,000 microseconds.
14. If C of Fig. 2 has a value of 0.0015 microfarads, R should have a value of
(a) 20,000 (b) 50,000 (c) 2,000,000 (d) 66 ohms.
15. An FM signal generator employing a motor-driven variable condenser is known
as a (a) selsyn (b) PPI (c) rotating vector (d) wobbulator.
Quizzes from vintage electronics magazines such as Popular
Electronics, Electronics-World, QST, and Radio News were published
over the years - some really simple and others not so simple. Robert P. Balin
created most of the quizzes for Popular Electronics. This is a listing
of all I have posted thus far.
Radio Quiz - December 1947 Radio-Craft
Quiz - October 1955 Radio & Television News
- Electronics Physics
Quiz - March 1974 Popular Electronics
- A Baffling Quiz
- January 1968 Popular Electronics
- Electronics IQ
Quiz - May 1967 Popular Electronics
- Plug and Jack
Quiz - December 1967 Popular Electronics
Switching Quiz - October 1967 Popular Electronics
Angle Quiz - September 1967 Popular Electronics
Electronics Quiz - July 1967 Popular Electronics
- FM Radio
Quiz - April 1950 Radio & Television News
- Bridge Circuit
Quiz -December 1966 Popular Electronics
- Diode Function
Quiz - August 1965 Popular Electronics
- Diagram Quiz,
August 1966 Popular Electronics
- Quist Quiz - November
- TV Trouble Quiz,
July 1966 Popular Electronics
- Electronics History Quiz,
December 1965 Popular Electronics
- Scope-Trace Quiz,
March 1965 Popular Electronics
Circuit Analogy Quiz, April 1973
Test Your Knowledge of Semiconductors, August 1972 Popular Electronics
- Ganged Switching
Quiz, April 1972 Popular Electronics
- Lamp Brightness
Quiz, January 1969 Popular Electronics
- Lissajous Pattern Quiz, September 1963 Popular Electronics
Quizoo, October 1962 Popular Electronics
- Electronic Photo Album Quiz, March 1963 Popular Electronics
- Electronic Alphabet Quiz, May 1963 Popular Electronics
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960 Popular Electronics
- Vector-Circuit Matching Quiz, June 1970 Popular Electronics
Quiz, September 1961 Popular Electronics
- RC Circuit Quiz,
June 1963 Popular Electronics
- Diode Quiz, July
1961 Popular Electronics
- Electronic Curves Quiz, February 1963 Popular Electronics
- Electronic Numbers Quiz, December 1962 Popular Electronics
- Energy Conversion Quiz, April 1963 Popular Electronics
- Coil Function
Quiz, June 1962 Popular Electronics
Co-Inventors Quiz - January 1965 Electronics World
"-Tron" Teasers Quiz - October 1963 Electronics World
- Polarity Quiz
- March 1968 Popular Electronics
I.Q. Quiz - October 1948 Radio & Television News
- Amplifier Quiz
Part I - February 1964 Popular Electronics
Quiz - February 1967 Popular Electronics
Frequency Quiz - September 1965 Popular Electronics
Metals Quiz - October 1964 Popular Electronics
Measurement Quiz - August 1967 Popular Electronics
Quiz, June 1966 Popular Electronics
Geometry Quiz, January 1965 Popular Electronics
Factor Quiz, November 1966 Popular Electronics
Math Quiz, November 1965 Popular Electronics
- Series Circuit
Quiz, May 1966 Popular Electronics
Quiz, March 1966 Popular Electronics
Quiz: Test Your Sales Ability - April 1947 Radio News
Analogy Quiz, November 1961 Popular Electronics
Coupling Quiz, August 1973 Popular Electronics
- Electronics Analogy Quiz, August 1960 Popular Electronics
- Audio Quiz, April
1955 Popular Electronics
- Electronic Unit
Quiz, May 1962 Popular Electronics
Circuit Quiz, June 1968 Popular Electronics
- Quiz on AC Circuit Theory, December 1970 Popular Electronics
- Magnetic Phenomena Quiz, February 1962 Popular Electronics
- Electronics Geography Quiz, April 1970 Popular Electronics
Menu Quiz, August 1963 Popular Electronics
- Electronic Noise Quiz, August 1962 Popular Electronics
- Electronic Current Quiz, October 1963 Popular Electronics
- Electronic Inventors Quiz, November 1963 Popular Electronics
- Resistor Function
Quiz, January 1962 Popular Electronics
- Electronic Measurement Quiz, January 1963 Popular Electronics
- Vacuum Tube Quiz,
February 1961 Popular Electronics
- Kool-Keeping Kwiz, June
1970 Popular Electronics
- Find the Brightest
Bulb Quiz, April 1960 Popular Electronics
Where Do the Scientists Belong? - Feb 19, 1949 Saturday Evening
Answers To "FM Quiz"
15 correct ... excellent
13 to 14 correct ...very good
10 to 12 correct ... good
8 to 9 correct ... fair
7 or less correct ... poor
Posted March 18, 2020