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Showing posts from January, 2014

Mistakes...

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Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth. -- Jules Verne



FCC Technician Exam Question Of The Day (T1A04)

Q) Which of the following meets the FCC definition of harmful interference?

A) That which seriously degrades, obstructs, or repeatedly interrupts a radio communication service operating in accordance with the Radio Regulations.

NJ2X Notes:
A "lid" is an amateur radio slang word used to denote a poor operator.  Causing harmful interference on the amateur bands is a sure way to gain a reputation as "lid".  It is also an effective way to receive a notice from the FCC with the possibility of a $10,000 fine.

FCC Technician Exam Question Of The Day (T1A09)

Q) Who selects a Frequency Coordinator?

A) Amateur operators in a local or regional area whose stations are eligible to be auxiliary or repeater stations.

NJ2X Notes:
The ARRL is not a frequency coordinator.  This is a common misunderstanding.

FCC Technician Exam Question Of The Day (T6D01)

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Q) Which of the following devices or circuits changes an alternating current into a varying direct current signal?

A) Rectifier


NJ2X Notes:
A rectifier is an electrical device based on the diode that converts alternating current (AC) to direct current (DC).  The process is known as rectification.

 Check out NJ2X.COM for other FCC Technician Exam questions, answers, and explanations.

FCC Technician Exam Question Of The Day (T1A08)

Q) Which of the following entities recommends transmit/receive channels and other parameters for auxiliary and repeater stations?

A) Frequency Coordinator.

NJ2X Notes:
The ARRL is not a Frequency Coordinator, nor does the ARRL "certify" coordinators. Frequency Coordinators are volunteers normally appointed by a coordinating body.

FCC Technician Exam Question Of The Day (T6A02)

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Q) What type of component is often used as an adjustable volume control?

A) Potentiometer

NJ2X Notes:
The potentiometer (or "pot") is a variable resistor. 



These are commonly used in electronic devices as a three-terminal resistor with a continuously adjustable tapping point controlled by rotation of a shaft or knob.  These variable resistors are known as potentiometers when all three terminals are present, since they act as a continuously adjustable voltage divider. A common example is a volume control for a radio, audio amplifier, or audio mixer.

FCC Technician Exam Question Of The Day (T6A11)

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Q) Which battery type is not rechargeable?

A) Carbon-zinc


NJ2X Notes:
A zinc–carbon battery is made up of a zinc outer canister that serves as both a container and negative terminal. The positive terminal is a carbon rod surrounded by a mixture of manganese dioxide and carbon powder with an electrolyte of paste of zinc chloride and ammonium chloride dissolved in water.  A typical A, AA, C, or D zinc-carbon cell has an electromotive force (emf) about 1.5V.  Zinc-carbon batteries are not rechargeable.

FCC Technician Exam Question Of The Day (T6A09)

Q) What electrical component is used to protect other circuit components from current overloads?

A) Fuse


NJ2X Notes:
Fuses play an important role by protecting a circuit from current overload.  Fundamentally a fuse is a short length of wire in a glass envelope that will melt at or above a specific current level.  The basic idea is to design a circuit so that the fuse will break down before the wires and components are destroyed or catch fire.  You want the fuse to be the weakest link in the electrical chain.

False facts...

False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for every one takes a salutary pleasure in proving their falseness. -- Charles Darwin

FCC Technician Exam Question Of The Day (T6A08)

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Q) What electrical component is used to connect or disconnect electrical circuits?

A) Switch

NJ2X Notes:
This is a common sense answer.  We use switches every day to turn circuits on and off in our homes (e.g. a light switch).

FCC Technician Exam Question Of The Day (T5D05)

Q) What is the resistance in a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes?

A) 8 ohms

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:

R = E / I
R = 12 volts / 1.5 amperes = 8 ohms


This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

FCC Technician Exam Question Of The Day (T5D08)

Q) What is the current flowing through a 100-ohm resistor connected across 200 volts?

A) 2 amperes

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:

I = E / R
I = 200 volts / 100 ohms = 2 amperes


This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

FCC Technician Exam Question Of The Day (T7A07)

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Q) If figure T5 represents a transceiver in which block 1 is the transmitter portion and block 3 is the receiver portion, what is the function of block 2?

A) A transmit-receive switch


NJ2X Notes:


FCC Technician Exam Question Of The Day (T1A10)

Q) What is the FCC Part 97 definition of an amateur station?

A) A station in an Amateur Radio Service consisting of the apparatus necessary for carrying on radio communications.


NJ2X Note:
A good approach to the Part 97 questions on the exam is to simply memorize the answers.  It is also helpful to read the FCC Part 97 rules (see our article, Part 97, do I really need to read it?).  There is a payback for your effort.  Once licensed, you need to know the rules in order to assure that you are following them.  As the old saying goes, Ignorantia juris non excusat which is Latin for, "ignorance of the law excuses no one".

FCC Technician Exam Question Of The Day (T5D12)

Q) What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it?

A) 20 volts

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:
E = I * R
E = 2 amperes * 10 ohms = 20 volts

FCC Technician Exam Question Of The Day (T5D09)

Q) What is the current flowing through a 24-ohm resistor connected across 240 volts?

A) 10 amperes

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:
I = E / R
I = 240 volts / 24 ohms = 10 amperes

Discovering principles

Every science has for its basis a system of principles as fixed and unalterable as those by which the universe is regulated and governed. Man cannot make principles; he can only discover them. -- Thomas Paine

FCC Technician Exam Question Of The Day (T5D07)

Q) What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?

A) 1.5 amperes

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:
I = E / R
I = 120 volts / 80 ohms = 1.5 amperes

FCC Technician Exam Question Of The Day (T5D06)

Q) What is the resistance of a circuit that draws 4 amperes from a 12-volt source?

A) 3 ohms

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:
R = E / I
R = 12 volts / 4 amperes = 3 ohms

FCC Technician Exam Question Of The Day (T5D04)

Q) What is the resistance of a circuit in which a current of 3 amperes flows through a resistor connected to 90 volts?

A) 30 ohms

NJ2X Notes:
Ohm's Law was discovered by Georg Simon Ohm and is worth committing to memory:

E = I * R

or by manipulating the terms algebraically:

I = E / R

or

R = E / I

In this example:

R = E / I
R = 90 volts / 3 amperes = 30 ohms

FCC Technician Exam Question Of The Day (T6D08)

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Q) Which of the following is used together with an inductor to make a tuned circuit?

A) Capacitor


NJ2X Notes:
A tuned circuit is also called a resonant circuit and is made up of an inductor and a capacitor connected together.  A mechanical analog for a resonator circuit is the tuning fork which stores energy while oscillating at its resonant frequency.



FCC Technician Exam Question Of The Day (T3A04)

Q) What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?

A) Signals could be significantly weaker

NJ2X Notes:
Both receive and transmit antennas must have the same spatial orientation, the same polarization sense and the same axial ratio in order to maximize reception.  Antennas that are not aligned or do not have the same polarization will have reduced power transfer.  The reduction in power transfer equates to a loss in overall efficiency and performance.

It is very difficult to receive a horizontally transmitted wave with a receive antenna that is vertically polarized due to the polarization mismatch which can cause a 20dB loss.

This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

FCC Technician Exam Question Of The Day (T5B10)

Q) What is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts?

A) 6 dB

NJ2X Notes:
The following formula will allow you calculate the ratio in decibels given two different power values.

dB = 10 * Log(Pa / Pb)

Using the figures in the question:
dB = 10 * Log (12 / 3)
dB = 10 * Log(4)
dB = 10 * 0.6
dB = 6

This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

FCC Technician Exam Question Of The Day (T5B09)

Q) What is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts?

A) 3 dB

NJ2X Notes:
The following formula will allow you calculate the ratio in decibels given two different power values.

dB = 10 * Log(Pa / Pb)

Using the figures in the question:
dB = 10 * Log (10 / 5)
dB = 10 * Log(2)
dB = 10 * 0.301
dB = 3.01
which is approximately 3 dB



This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

Ignorance of science...

It has become almost a cliché to remark that nobody boasts of ignorance of literature, but it is socially acceptable to boast ignorance of science and proudly claim incompetence in mathematics. -- Richard Dawkins

FCC Technician Exam Question Of The Day (T3B03)

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Q) What are the two components of a radio wave?

A) Electric and magnetic fields


NJ2X Notes:
Electromagnetic waves have two components: the electric and the magnetic.  The two components are oriented perpendicular to each other.

This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

FCC Technician Exam Question Of The Day (T3A09)

Q) Which of the following is a common effect of “skip” reflections between the Earth and the ionosphere?

A) The polarization of the original signal is randomized


NJ2X Notes:
Antenna polarization is very important for line-of-sight VHF and UHF communications since a mismatch between the transmitter antenna polarization and the reciever antenna polarization results in significant signal loss.

Signal polarization on HF and 6M typically involve reflecting radio waves off the ionosphere or earth.  These reflections tend to randomly change the polarization.  The result is that differences between transmitting antenna polarization and receiving antenna polarization matter much less than on VHF and UHF line-of-sight communication.


This question is from the FCC Element 2 Technician Class Question Pool
Effective July 1, 2010 for examinations and is valid until June 30, 2014

FCC Technician Exam Question Of The Day (T5C03)

Q) What is the ability to store energy in a magnetic field called?

A) Inductance

NJ2X Notes:
Here is a little memory trick you may find helpful.   An inductor can be made from a coil of magnet wire which can store energy.

FCC Technician Exam Question Of The Day (T3A01)

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Q) What should you do if another operator reports that your station’s 2 meter signals were strong just a moment ago, but now they are weak or distorted?

A) Try moving a few feet, as random reflections may be causing multi-path distortion


NJ2X Notes:
Multi-path propagation occurs commonly with mobile and portable VHF / UHF operations. With multi-path propagation the signal received includes not only a direct line-of- sight radio wave, but also a large number of reflected radio waves.







The reflected waves can interfere with the line-of-sight wave causing distortion or poor reception.  Moving the transmitter a short distance can dramatically change the reflections thereby improving reception.

Remember this phenomena the next time you or a friend are having difficulty connecting a PC to wifi.  Moving the PC only a short distance can make enough of a difference that you are able to connect (and amaze your friend).

FCC Technician Exam Question Of The Day (T3A02)

Q) Why are UHF signals often more effective from inside buildings than VHF signals?

A) The shorter wavelength allows them to more easily penetrate the structure of buildings


NJ2X Notes:
The higher the frequency, the shorter the wavelength, and the smaller the opening required to pass signals through.

FCC Technician Exam Question Of The Day (T3A03)

Q) What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands?

A) Horizontal


NJ2X Notes:
Horizontally polarized antennas include: dipole, yagi, quads, and horizontal loop antennas.

FCC Technician Exam Question Of The Day (T3A07)

Q) What type of wave carries radio signals between transmitting and receiving stations?

A) Electromagnetic


NJ2X Note:
This question is a good of example of how you can increase your odds of selecting the correct answer by first eliminating the obvious wrong answers.

Here are the four choices that will appear on the exam for this question:

A. Electromagnetic
B. Electrostatic
C. Surface acoustic
D. Magnetostrictive

B. Electrostatic - This is synonym for static electricity.  Fun to zap someone after shuffling across a carpeted floor.  Not a very useful for transmitting with a radio.

C. Surface acoustic - This is a nonsense term.  Acoustic refers to sound waves that we can hear with our ears.  Has nothing to do with transmitting radio signals.

D. Magnetostrictive - This is a real term though unrelated to radio.  This is also trick answer since it incorporates the "magneto" which sounds a little like "electromagnetic".

Enthusiasm for science...

I am often amazed at how much more capability and enthusiasm for science there is among elementary school youngsters than among college students.  -- Carl Sagan

FCC Technician Exam Question Of The Day (T5C01)

Q) What is the ability to store energy in an electric field called?

A) Capacitance

NJ2X Notes:
Here is a little memory trick that works for us, "storing energy requires capacity".

FCC Technician Exam Question Of The Day (T5C02)

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Q) What is the basic unit of capacitance?

A) The farad

NJ2X Notes:
The capacitance unit of measure, "farad" is named after the great scientific genius, Michael Faraday.

Reflections on NJ2X's LoTW statistics for 2013

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As we start the new year 2014, we reviewed our LoTW stats to see how our year in ham radio went.

1/16/2013                  1/1/2014                       Delta
3,556 QSO records    3,955 QSO records      399 QSO records
1,486 QSL records     1,780 QSL records      294 QSL records
42% QSL/QSO           45% QSL/QSO           74% QSL/QSO
54,750 LoTW users    62,151 LoTW users    7401 increase in registered LoTW users

It is nice to see the number of registered LoTW users going up each year.  The 14% increase of users helped drive up everyone's LoTW QSL/QSO ratios.  We saw a 3% increase in our overall QSL/QSO ratio in 2013 as a result.  Tell your friends now is a great time to jump in and join The Logbook of The World.



I am looking forward to the day when we see the number of registered LoTW users increase to 100,000 or 200,000 hams worldwide.  How about 1,000,000 LoTW subscribers?  What will the average QSL/QSO LoTW ratio be when that happens?  Pretty darn good I am sure.

So how does …

FCC Technician Exam Question Of The Day (T5C08)

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Q) What is the formula used to calculate electrical power in a DC circuit?

A) Power (P) equals voltage (E) multiplied by current (I)

NJ2X Notes:
There is a really excellent method for memorizing the various power/voltage/current relationships called simply the "PIE" method or also the "Power Triangle".




To use this, memorize drawing a triangle with the letter PIE arranged as above which stand for Power (P), Current (I), and Voltage (E) .  Then cover any letter to find the formula (see above).  Presto magico - easy as PIE!