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Showing posts from April, 2014

FCC Technician Exam Question Of The Day (T7B12)

Q) What does the acronym "BER" mean when applied to digital communications systems?


A) Bit Error Rate


NJ2X Notes:
The number of bit errors is the number of received data stream bits over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors.  The bit error rate (BER) is the number of bit errors divided by the total number of transferred bits during a studied time interval.

FCC Technician Exam Question Of The Day (T7C07)

Q) What happens to power lost in a feedline?

A) It is converted into heat

NJ2X Notes:
Energy can be neither created nor destroyed.  The law of conservation of energy (physics), states that the total amount of energy in an isolated system remains constant over time (conserved).  For an isolated system (such as a radio station and surrounding space), this law means that energy can change its location within the system, and that it can change form within the system.  For instance, some portion of the radio frequency (RF) energy transmitted through a feedline can be lost as heat.

FCC Technician Exam Question Of The Day (T7C10)

A) Why should the outer jacket of coaxial cable be resistant to ultraviolet light?

D. Ultraviolet light can damage the jacket and allow water to enter the cable


NJ2X Notes:
Ultraviolet light is very powerful and can cause deterioration in the outer jacket of coaxial cable unless specifically designed to be resistant.

FCC Technician Exam Question Of The Day (T7B10)

Q) What might be the problem if you receive a report that your audio signal through the repeater is distorted or unintelligible?

A. Your transmitter may be slightly off frequency
B. Your batteries may be running low
C. You could be in a bad location
D. All of these choices are correct


NJ2X Notes:
At one time or another most hams experience all three of these issues.  If your tuned slightly off frequency, simply adjust your radio.  If your batteries are low, either switch batteries, recharge them, or switch to another power source (e.g. car power).  If you are in a bad location, try moving to see if it helps improve your signal.

FCC Technician Exam Question Of The Day (T8C05)

Q) What is a grid locator?

A) A letter-number designator assigned to a geographic location

NJ2X Notes:
Grid locator is also known as grid square or more formally as a Maidenhead locator.  A grid locator is a system for compressing both latitude and longitude into a short string of characters.  On shortwave frequencies, positions are reported at square precision, and on VHF and UHF, subsquare precision is used.



The ARRL's W1AW station in Newington, Connecticut, is found in grid locator FN31.
The "grid square" is indicated by the first two letters and two numbers.  Further precision can be specified by using the "subsquare" which is designated by the addition of two letters after the grid square, as FN44ig (W1AW's grid square with subsquare location).

FCC Technician Exam Question Of The Day (T7C09)

Q) Which of the following is the most common cause for failure of coaxial cables?

A) Moisture contamination

NJ2X Notes:
Moisture contamination is a common cause of failure in coaxial cables. However, what causes moisture contamination? In our own case, we have had it caused by chewing!  No, we do not have a penchant for dining on coaxial cable. However, it seems that squirels and dogs do. On one occasion, a squirel attacked and chewed the sheath of the coaxial cable that ran up the side of a large maple tree.  On another occasion, our dog was bored and decided to dig and chew on about 3 feet of Bury Flex coaxial cable.  Fortunately, neither animals were hurt. 

Expensive lessons on both occasions since the cables were useless once the jacket was penetrated.  The next time around we buried conduit to provide an underground run from the entrance to the point just below the antenna.  The cable is now safe from the elements, dogs, and lawn mowers.

Precise about something...

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There is no sense in being precise about something, when you don't even know what you are talking about.  -- John Von Neumann



FCC Technician Exam Question Of The Day (T8C04)

Q) Which of the following is good procedure when contacting another station in a radio contest?

A) Send only the minimum information needed for proper identification and the contest exchange


NJ2X Notes:
Efficiency counts in radio contests.  The more stations you can contact in a given period of time the higher your score.  You gain an edge over the competition when your contact rate exceeds theirs.  One way to improve your rate is to make sure you understand the specific requirements for contest you are participating in regarding the exchange.  This allows you to both deliver, receive, and log the required information.  Including extra unnecessary information only slows your rate (and that of your contact).

FCC Technician Exam Question Of The Day (T8B04)

Q) Which amateur stations may make contact with an amateur station on the International Space Station using 2 meter and 70 cm band amateur radio frequencies?

A) Any amateur holding a Technician or higher class license

NJ2X Notes:
International Space Station Size & Mass
Module Length: 167.3 feet (51 meters) Truss Length: 357.5 feet (109 meters) Solar Array Length: 239.4 feet (73 meters) Mass: 924,739 pounds (419,455 kilograms) Habitable Volume: 13,696 cubic feet (388 cubic meters) Pressurized Volume: 32,333 cubic feet (916 cubic meters) Power Generation: 8 solar arrays = 84 kilowatts Lines of Computer Code: approximately 2.3 million

FCC Technician Exam Question Of The Day (T7C03)

Q) What, in general terms, is standing wave ratio (SWR)?

A) A measure of how well a load is matched to a transmission line

NJ2X Notes:
Standing wave ratio (SWR) is the ratio of the amplitude of a partial standing wave at an antinode (maximum) to the amplitude at an adjacent node (minimum), in an electrical transmission line.

SWR is used as a measure of efficiency for radio transmission lines.  SWR is important since it provides an indication of the radio waves reflected back toward the transmitter.  Under ideal conditions, a radio transmission cable would have an SWR of 1:1 (1 to 1) indicating that all power is being delivered to the antenna and none being reflected back to the transmitter.  An infinite SWR indicates all power is being reflected back to the transmitter (with none being delivered to the antenna).  High SWR ratios are to be avoided and can indicate RF is being radiated in the shack, RF is being wasted as heat, and equipment failure may result.

FCC Technician Exam Question Of The Day (T7B07)

Q) Which of the following may be useful in correcting a radio frequency interference problem?

A. Snap-on ferrite chokes
B. Low-pass and high-pass filters
C. Band-reject and band-pass filters
D. All of these choices are correct

NJ2X Notes:
We use ferrite chokes for both bringing down the general received interference level and preventing RFI on our consumer grade electronics.  We have installed ferrites throughout our house on our phone lines, power cables, and cable TV coaxial cables.  Look for type for  type 31 and 43 ferrites at hamfests.

We also have low-pass filters installed between the antenna and our shortwave receiver.

FCC Technician Exam Question Of The Day (T7D11)

Q) Which of the following precautions should be taken when measuring circuit resistance with an ohmmeter?

A) Ensure that the circuit is not powered

NJ2X Notes:
Ensure that the circuit is not powered.Be certain the circuit is deenergized and discharged before connecting an ohmmeter. Do not apply power to a circuit while measuring resistance.

FCC Technician Exam Question Of The Day (T8C01)

Q) Which of the following methods is used to locate sources of noise interference or jamming?

A) Radio direction finding

 NJ2X Notes:
Radio direction finding involves using antennas and receivers to determine the location of an RF source.  The are many different techniques:
Directional antennas - Using highly directional antennas such as yagi's, loops, etc. you can determine the direction of the signal.Pseudo-doppler  - antennas are arranged in a circular array and then sequentially sampled to simulate the effect of a rotating antenna.  This modulates the received signal and the phase of this modulation can be used to determine the direction of the signal.Phase interferometer - the phase difference between two spacially separated antennas is used to determine the direction of the signal. Using triangulation in conjunction with the above techniques can help pinpoint a transmitter's location.

Law of Gravitation

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By such deductions the law of gravitation is rendered probable, that every particle attracts every other particle with a force which varies inversely as the square of the distance. The law thus suggested is assumed to be universally true. — Sir Isaac Newton


FCC Technician Exam Question Of The Day (T8B09)

Q) What causes "spin fading" when referring to satellite signals?

A) Rotation of the satellite and its antennas

NJ2X Notes:
Aside from the above natural sources of signal fading, the satellite itself is often spinning.  This spinning continuously changes the orientation of its antennas with respect to your ground station.  Changes in antenna orientation cause the signal strength to fade periodically.

FCC Technician Exam Question Of The Day (T8A08 )

Q) What is the approximate bandwidth of a single sideband voice signal?

A) 3 kHz

NJ2X Notes:
Single Sideband is also referred to as SSB.  The transmitted bandwidth of an SSB signal is dependent on the particular rig being used.  A common transmitted bandwidth is 3 kHz.  SSB receivers often include one or more filters which can further reduce received bandwidth (e.g. 2.8 kHz, 2.4 kHz, 1.9 kHz).  Filtering can improve intelligibility of weak signals received in crowded conditions.

FCC Technician Exam Question Of The Day (T8C02)

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Q) Which of these items would be useful for a hidden transmitter hunt?

A) A directional antenna

NJ2X Notes:
Direction antennas often seen in transmitter hunting include the dipole, Yagi, and Loop antennas.



FCC Technician Exam Question Of The Day (T7D02)

Q) What is the correct way to connect a voltmeter to a circuit?

A) In parallel with the circuit


NJ2X Notes:
Connecting a voltmeter to a circuit in parallel allows the measurement of the voltage drop across the circuit.

FCC Technician Exam Question Of The Day (T8C03)

Q) What popular operating activity involves contacting as many stations as possible during a specified period of time?

A) Contesting

 NJ2X Notes:
Radio contesting is great fun and enjoyed by a growing number of hams world wide.  Besides the fun factor, radio sports sharpen operating skills and encourage people to stay active on the air.

FCC Technician Exam Question Of The Day (T7D04)

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Q) Which instrument is used to measure electric current?

A) An ammeter

NJ2X Notes:
An ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in amperes (A).


FCC Technician Exam Question Of The Day (T9B03)

Q) Why is coaxial cable used more often than any other feedline for amateur radio antenna systems?

A) It is easy to use and requires few special installation considerations

NJ2X Notes:
Coaxial cable has many advantages for radio amateurs.  Here are a few:
Can be buried or placed on the groundCan be routed in close proximity to metallic objectsCan be easily pulled through walls and conduitRelatively low feed line lossEasy on/off connectorsLong lasting and durableWaterproofDoesn't radiate (in most applications)Shields the signal carried on the cable from interference

Pure or applied science...

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Frequently, I have been asked if an experiment I have planned is pure or applied science; to me it is more important to know if the experiment will yield new and probably enduring knowledge about nature. If it is likely to yield such knowledge, it is, in my opinion, good fundamental research; and this is more important than whether the motivation is purely aesthetic satisfaction on the part of the experimenter on the one hand or the improvement of the stability of a high-power transistor on the other. — William B. Shockley

FCC Technician Exam Question Of The Day (T8B02)

Q) How much transmitter power should be used on the uplink frequency of an amateur satellite or space station?

A) The minimum amount of power needed to complete the contact


NJ2X Notes:
QRP (low power) operators already understand the meaning of this rule.  They accomplish DX (long distance) contact with just a few watts or sometimes even miliwatts.  It is rather fun to turn down the power during a contact to see "how low you can go".

This rule becomes even more critical with a space station since transmitting on the uplink at greater power than necessary increases the chances you will cause harmful interference.



FCC Technician Exam Question Of The Day (T6D05)

Q) What type of circuit controls the amount of voltage from a power supply?

A) Regulator

NJ2X Notes:

The objective for a voltage regulator is to provide constant DC output voltage and to continuously hold the output voltage at the design value regardless of changes in load current or input voltage.

FCC Technician Exam Question Of The Day (T6D04)

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Q) Which of the following can be used to display signal strength on a numeric scale?

A) Meter


NJ2X Notes:

FCC Technician Exam Question Of The Day (T6B11)

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Q) Which semiconductor component has a gate electrode?

A) Field effect transistor


NJ2X Notes:
All FETs have gate, drain, and source terminals (three-terminal device) that are used to control current passing through the device.  The electrical resistance between the source and the drain can be manipulated by changing the voltage between the gate and source.  The FET is used in a wide variety of applications including amplifiers and power supplies.



FCC Technician Exam Question Of The Day (T6C09)

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Q) What is component 4 in figure T2?

A) Transformer

NJ2X Notes:
Check out NJ2X.COM for other FCC Technician Exam questions related to the schematic symbol.

FCC Technician Exam Question Of The Day (T6D06)

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Q) What component is commonly used to change 120V AC house current to a lower AC voltage for other uses?

A) Transformer

NJ2X Notes:
The ubiquitous "wall-wart" housing contains a transformer along with a few other components.  This device steps down 120V AC house current to a lower AC voltage.
Element 2 Technician Class Question Pool

FCC Technician Exam Question Of The Day (T6C12)

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Q) What do the symbols on an electrical circuit schematic diagram represent?

A) Electrical components


NJ2X Notes:
A schematic is a diagram that represents the electrical components of a circuit using abstract, graphic symbols (rather than realistic pictures or mathematical equations).



Check out NJ2X.COM for other FCC Technician Exam questions related to the schematic symbol.

Experience with ignorance and doubt...

“The scientist has a lot of experience with ignorance and doubt and uncertainty, and this experience is of very great importance, I think. When a scientist doesn’t know the answer to a problem, he is ignorant. When he has a hunch as to what the result is, he is uncertain. And when he is pretty damn sure of what the result is going to be, he is still in some doubt. We have found it of paramount importance that in order to progress, we must recognize our ignorance and leave room for doubt. Scientific knowledge is a body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none absolutely certain. Now, we scientists are used to this, and we take it for granted that it is perfectly consistent to be unsure, that it is possible to live and not know. But I don’t know whether everyone realizes this is true. Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to ques…

FCC Technician Exam Question Of The Day (T6D10)

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Q) What is the function of component 2 in Figure T1?
A) Control the flow of current

NJ2X Notes:
The schematic symbol illustrated by component 2 is a transistor.


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 (T6D09)

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Q) What is the name of a device that combines several semiconductors and other components into one package?

A) Integrated circuit

NJ2X Notes:
The ubiquitous integrated circuit is also referred to as an IC or chip.  The integrated circuit is manufactured through a lithography process that places trace elements onto a substrate of silicon semiconductor material.  The semiconductor devices are interconnected to form circuits.
This is an interesting 11 minute video from Philips about how integrated circuits are manufactured.



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 (T6C13)

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Q) Which of the following is accurately represented in electrical circuit schematic diagrams?

A) The way components are interconnected


NJ2X Notes:
Check out NJ2X.COM for other FCC Technician Exam questions related to the schematic symbol.





FCC Technician Exam Question Of The Day (T6D03)

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Q) What type of switch is represented by item 3 in figure T2?
A) Single-pole single-throw


NJ2X Notes:
A common abreviation designation for single-pole single-throw switch is SPST.  The single-pole single-throw switch is the most common on/off switch.  The number of "poles" refers to the number of separate circuits which are controlled by the switch.  The number of "throws" refers to the number of separate positions that the switch can select.