ERRATA for the No-Nonsense Extra Class License Study Guide, ver 1.3
In the explanation for question E5B04, there's an error in an equation. The paragraph currently reads:
“The equivalent resistance of two 1 MΩ resistors in parallel is 500 kΩ. The equivalent
capacitance of two 220 μF capacitors in parallel is 440 μF. The time constant is
RxC = 440 x 10-6 x 500 x 105 = 220 s.”
500 kΩ should instead be 500 x 103, and the paragraph should read:
“The equivalent resistance of two 1 MΩ resistors in parallel is 500 kΩ. The equivalent
capacitance of two 220 μF capacitors in parallel is 440 μF. The time constant is
RxC = 440 x 10-6 x 500 x 103 = 220 s.”
In section E5C, I failed to describe how to calculate the total impedance when a resistance and a
reactance are in parallel. The formula to use is:
Z = (R x X) / √(R² + X²)
To see how that's used to find the answer to a question, let's look at E5C05. That question asks, “In
polar coordinates, what is the impedance of a network consisting of a 400-ohm-reactance inductor in
parallel with a 300-ohm resistor?
Z = (R x X) / √(R² + X²)
= (300 x 400) / √(300² + 400²)
= 120000 / 500
= 240 Ω
The formula to calculate the phase angle is
Phase angle = 90° - tan-1 (X/R), where tan-1 is the inverse tangent, or in other words, the angle whose
tangent is equal to X/R. In this problem,
Phase angle = 90° - tan-1 (X/R) = 90° - tan-1 (400/300) = 90° - 53.1° = 36.9°,
In section E5C, there is an incorrect answer. The current edition reads, “In polar coordinates, what is
the impedance of a network comprised of a 300-ohm-reactance inductor in series with a 400-ohm
resistor is 500 ohms at an angle of 53 degrees. (E5C08)” It should read, “In polar coordinates, the
impedance of a network comprised of a 300-ohm-reactance inductor in series with a 400-ohm resistor
is 500 ohms at an angle of 37 degrees. (E5C08)”
_________wants2bagirl1300
In the section on toroids, the last paragraph should read:
Using that equation, 35 turns will be required to produce a 5-microhenry inductor using a
powdered-iron toroidal core that has an inductance index (A L) value of 40 microhenrys/100
turns. (E6D12)
N = 100 x √(5/40) = 100 x .353 = 35.3 turns
Section E6E is missing question E6E10. The first paragraph of that section should now read:
Piezoelectric crystals are used in several amateur radio applications. They are called
piezoelectric crystals because they rely on the piezoelectric effect, which is the physical
deformation of a crystal by the application of a voltage. (E6E03) The equivalent circuit of a
quartz crystal includes motional capacitance, motional inductance and loss resistance in
series, with a shunt capacitance representing electrode and stray capacitance. (E6E10)
In section E6D, there is a paragraph that reads:
The formula for calculating the inductance of a powdered-iron core toroid inductor is:
L = AL×N2/10,000
where L = inductance in microhenries, AL = inductance index in µH per 1000 turns, and N =
number of turns.
The last part of that paragraph should read, “A L = inductance index in µH per 100 turns.”
In section E7A, there is a sentence that reads, “Table E7-3 shows a truth table that describes the logical
operation of an OR gate.” It should read, “Table E7-3 shows a truth table that describes the logical
operation of an XNOR gate.” The sentence that gives the answer to question E7A09 is correct, but that
question has been withdrawn from the question pool anyway.