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Showing posts from June, 2014

FCC Technician Exam Question Of The Day (T8D11)

Q) What is a "parity" bit?

A) An extra code element used to detect errors in received data


NJ2X Notes:
A parity bit is used to detect errors in a data transmission.  It is a simple technique.  With "even parity", the number of bits with the value one are counted and then the parity bit is set such that the sum of all the bits is even.  With "odd" parity, the number of bits with the value of one are counted and then a parity bit is set such that the sum of all the bits is odd. 

With even parity, the receiver then checks the parity count and confirms it is even.  If data is received that is not even then the receiver recognizes that an error has occured.

Even Parity Example:
00001111 = 4, parity bit = 0, sum of all bits is even
11001101 = 5, parity bit = 1, sum of all bits is even
11111111 = 8, parity bit = 0, sum of all bits is even
01111111 = 7, parity bit = 1, sum of all bits is even




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2014 Field Day Fun @ Monterey Bay Amateur Radio Association (N6IJ)

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Field Day is FUN!  There is nothing quite like setting up and operating outdoors.

For some hams it is challenge of setting up temporary radio operations in the great outdoors.  For these amateurs, assembling the gear, hoisting and adjusting antennas, solving problems, and making everything work is what it is all about.

Other hams it is about lighting up the ether and operating in the wild.  For these amateurs, the fun is in making great contacts in the great outdoors with perhaps a bit of the old competitive spirit mixed in.

For Field Day 2014, KC2VSR, NJ2X, and KG6UBG set up two outdoor stations at the home of the Monterey Bay Amateur Radio Association (MBARA) headquarters in Marina, California.  We operated using the MBARA call N6IJ.  The site was formerly part of the Fort Ord military base which gave the operations a historical feel.

California weather is famously mild and we were not disappointed during Field Day 2014.  The skies were blue and there was a light cool breeze coming …

FCC Technician Exam Question Of The Day (T0B07)

Q) Which of the following is an important safety rule to remember when using a crank-up tower?

A) This type of tower must never be climbed unless it is in the fully retracted position


NJ2X Notes:
Crank-up masts are typically held in the extended position by a single cable.  If this cable were to break then the sections would collapse suddenly.  Crank-up towers must never be climbed unless it is in the fully retracted position.



Amateur Radio ARRL Field Day Food - QSL Quiche

Field day has a long tradition for great amateur radio fun combined with good eats.  It takes a lot of calories to setup a field station, operate for long hours, and talk to friends near and far.  Well maybe not all that many calories but tasty food definitely enhances the fun. 

As much as we do love grilled hot dogs and hamburgers, it is also fun to wow your friends with a dish that looks and tastes great (while also easy).  Here is an easy-to-make recipe that yields results sure to please 4 or 5 hungry hams - QSL Quiche.

6 ounces cooked ham, cut into 1/4 inch cubes
3/4 cup broccoli, cut into bite size
2 ounces Monterrey jack pepper cheese
2 ounces cheddar cheese
Grated Parmesan cheese
8 large eggs
1/2 cup milk
1/2 teaspoon salt
1/4 teaspoon pepper
A dash of your favorite hot sauce

Step #1 Heat oven to 375°F and grease a 9-inch pie plate.
Step #2 Scatter ham, broccoli and cheeses evenly in pie plate.
Step #3 Whisk remaining ingredients in a bowl until blended.
Step #4 Pour ingr…

FCC Technician Exam Question Of The Day (T0B09)

Q) Why should you avoid attaching an antenna to a utility pole?

A) The antenna could contact high-voltage power wires

NJ2X Notes:
It is important to assure that antenna wires cannot come into contact with overhead power lines.  Do not attempt to attach antennas to utility poles since the antenna would be in close proximity to high-voltage power wires.

Archimedes was my ideal...

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Archimedes was my ideal. I admired the works of artists, but to my mind, they were only shadows and semblances. The inventor, I thought, gives to the world creations which are palpable, which live and work. -- Nikola Tesla


FCC Technician Exam Question Of The Day (T8C10)

Q) How do you select a specific IRLP node when using a portable transceiver?

A) Use the keypad to transmit the IRLP node ID

NJ2X Notes:
IRLP =  Internet Radio Linking Project
IRPL is used to link amateur radio systems without the use of RF links, leased lines, or satellites.

FCC Technician Exam Question Of The Day (T0B08)

Q) What is considered to be a proper grounding method for a tower?

A) Separate eight-foot long ground rods for each tower leg, bonded to the tower and each other

NJ2X Notes:
Lightning protection systems for towers and amateur radio equipment is good engineering.

FCC Technician Exam Question Of The Day (T8D07)

Q) What is PSK31?

A) A low-rate data transmission mode

NJ2X Notes:
PSK31 is a digital mode and a whole lot of fun.  All you need to get started with PSK31 is a computer, a program that supports PSK31 (many are free), and a transceiver.  We are avid PSK31 operators and hope to see you on the air.

FCC Technician Exam Question Of The Day (T8D09)

Q) What code is used when sending CW in the amateur bands?

A) International Morse

NJ2X Notes:
This is a fairly easy question to get right if you recognize that "CW" refers to Morse code.  If you know that then you can easily eliminate the wrong answers since none of them includes the word, "Morse".  CW stands for continuous wave and is often used interchangeably with the term Morse code.


FCC Technician Exam Question Of The Day (T8C08)

Q) What is required in place of on-air station identification when sending signals to a radio control model using amateur frequencies?

A) A label indicating the licensee's name, call sign and address must be affixed to the transmitter

NJ2X Notes:
§97.215 Telecommand of model craft. - An amateur station transmitting signals to control a model craft may be operated as follows:
(a) The station identification procedure is not required for transmissions directed only to the model craft, provided that a label indicating the station call sign and the station licensee's name and address is affixed to the station transmitter.
(b) The control signals are not considered codes or ciphers intended to obscure the meaning of the communication.
(c) The transmitter power must not exceed 1 W.

FCC Technician Exam Question Of The Day (T0B04)

Q) Which of the following is an important safety precaution to observe when putting up an antenna tower?

A) Look for and stay clear of any overhead electrical wires

NJ2X Notes:
Contact with overhead electrical wires is a significant risk when putting up an antenna.  Ladders, masts, towers, coaxial cable, and antenna wire are all potential conductors and must be kept well clear of overhead electrical wires.


FCC Technician Exam Question Of The Day (T0B03)

Q) Under what circumstances is it safe to climb a tower without a helper or observer?

A) Never

NJ2X Notes:
Be safe and always have a helper or observer involved whenever climbing a tower.  The safety of the climber may depend on the aid of the helper or observer.


X-rays...I am afraid of them...

X-rays ... I am afraid of them. I stopped experimenting with them two years ago, when I came near to losing my eyesight and Dally, my assistant practically lost the use of both of his arms. -- Thomas Edison

FCC Technician Exam Question Of The Day (T9B05)

Q) What generally happens as the frequency of a signal passing through coaxial cable is increased?

A) The loss increases

NJ2X Notes:
Coaxial cable loss (attenuation) increases as the singal frequency increases.  RF power is lost in several ways:
Resistive lossDielectric lossRadiated loss


FCC Technician Exam Question Of The Day (T9B06)

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Q) Which of the following connectors is most suitable for frequencies above 400 MHz?

A) A Type N connector

NJ2X Notes:
The Type N connector is superior to the UHF connector.  The N connector is waterproof and preserves the impedance match of the cable.  The N connector works very well at UHF frequencies too.



FCC Technician Exam Question Of The Day (T0B06)

Q) What is the minimum safe distance from a power line to allow when installing an antenna?

A) So that if the antenna falls unexpectedly, no part of it can come closer than 10 feet to the power wires

NJ2X Notes:
Be safe and keep well away from power lines when installing antennas.

FCC Technician Exam Question Of The Day (T8C07)

Q) What is the maximum power allowed when transmitting telecommand signals to radio controlled models?

A) 1 watt

NJ2X Notes:
Part 97

§97.215 Telecommand of model craft. - An amateur station transmitting signals to control a model craft may be operated as follows:
(a) The station identification procedure is not required for transmissions directed only to the model craft, provided that a label indicating the station call sign and the station licensee's name and address is affixed to the station transmitter.
(b) The control signals are not considered codes or ciphers intended to obscure the meaning of the communication.
(c) The transmitter power must not exceed 1 W.

FCC Technician Exam Question Of The Day (T9B08)

Q) Why should coax connectors exposed to the weather be sealed against water intrusion?

A) To prevent an increase in feedline loss


NJ2X Notes:
Water contamination of coaxial cable or intrusion in the connector is a sure way to cause problems including increased feedline loss, corrosion, SWR problems, ...  Be sure to seal coaxial connectors.

FCC Technician Exam Question Of The Day (T0B05)

Q) What is the purpose of a gin pole?

A) To lift tower sections or antennas

NJ2X Notes:
A jin-pole or gin pole is a device with a pulley on the end used for the purpose of lifting from a tower.  The gin pole can be detached, moved up, and re-attached to the upper segment for the purpose of lifting the next segment.  This process is then repeated until the final section of the tower is in place.

FCC Technician Exam Question Of The Day (T8B06)

Q) What can be used to determine the time period during which an amateur satellite or space station can be accessed?

A) A satellite tracking program


NJ2X Notes:
Your smartphone can be used to track satellites.  HamSatDroid for Android operating system mobile devices does the job.

Azden AZ-61 6m FM HT - Tip #4 - rebuilding the battery pack

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This is an article in a series regarding the Azden AZ-61 6m FM Transceiver.  One of the weak points of vintage handy-talkies (HT's) is the battery pack.  It is a fact that Ni-cad batteries (or any rechargeable for that matter) have limited useful life.  It is also a fact that radio manufacturers love to create proprietary battery packs for their radios.  If you buy a vintage HT you will likely end up having to replace or refurbish the battery pack.


Replacing the battery pack on the AZ-61 with new old stock (NOS) is unlikely.  It is possible to rebuild the battery pack yourself.  The process involves carefully cracking the case (a Dremel can help with this task), replacing the batteries, and then resealing case with tape.

Good DX and 73, NJ2X



Other related articles on NJ2X.COM:
Azden AZ-61 6m FM HT - Tip #1 - How to program the radio
Azden AZ-61 6m FM HT - Tip #2 - disabling "the beep"
Azden AZ-61 6m FM HT - Tip #3 - 1993 review article
Azden AZ-61 6m FM HT - Tip #4 - rebui…

I shall call them "X-rays"...

If the hand be held between the discharge-tube and the screen, the darker shadow of the bones is seen within the slightly dark shadow-image of the hand itself... For brevity's sake I shall use the expression 'rays'; and to distinguish them from others of this name I shall call them 'X-rays'. — Wilhelm Röntgen

FCC Technician Exam Question Of The Day (T8A11)

Q) What is the approximate maximum bandwidth required to transmit a CW signal?

A) 150 Hz

NJ2X Notes:
The abreviation, "CW" means, "continuous wave" and was used to differentiate the original spark-gap generated waves from the early days of radio.  CW is used to transmit morse code and is a very narrow bandwidth mode and very efficient.  As a result, CW is an excellent choice for attempting a contact under conditions where other modes are not making it.  For weak signal work, CW seems to punch through like magic.

FCC Technician Exam Question Of The Day (T8B01)

Q) Who may be the control operator of a station communicating through an amateur satellite or space station?

A) Any amateur whose license privileges allow them to transmit on the satellite uplink frequency



NJ2X Notes:
FCC Part 97
§97.207 Space station. - (a) Any amateur station may be a space station. A holder of any class operator license may be the control operator of a space station, subject to the privileges of the class of operator license held by the control operator.

NJ2X Kindle Edition is now available.

FCC Technician Exam Question Of The Day (T8A04)

Q) Which type of modulation is most commonly used for VHF and UHF voice repeaters?

A) FM

NJ2X Notes:
Working local contacts and participating in "nets" via repeaters is great fun and a very inexpensive way to get started in amateur radio.  A used 2m FM HT can be had very reasonably.  Try asking around a local amateur radio club or at a local hamfest.

FCC Technician Exam Question Of The Day (T8A10)

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Q) What is the typical bandwidth of analog fast-scan TV transmissions on the 70 cm band?

A) About 6 MHz

NJ2X Notes:
To get an idea what the mode looks like in operation, here is a nice video compilation of  amateur fast-scan television contacts by WDØAKX.

FCC Technician Exam Question Of The Day (T8A01)

Q) Which of the following is a form of amplitude modulation?

A) Single sideband

NJ2X Notes:
Single sideband is also referred to as SSB.  Single sideband is a way to make amplitude modulation more efficient.  AM produces a modulated output signal that has twice the bandwidth of the original signal along with a carrier signal.  SSB suppresses the carrier and channels all the power into one side-band.   SSB signals have 16 times greater efficiency than a conventional AM signal.

FCC Technician Exam Question Of The Day (T8A06)

Q) Which sideband is normally used for 10 meter HF, VHF and UHF single-sideband communications?

A) Upper sideband

NJ2X Notes:
SSB = Single Sideband
USB = Upper Sideband
LSB = Lower Sideband

The common convention is use LSB when operating below 10 MHz and USB when operating above 10MHz.

Azden AZ-61 6m FM HT - Tip #3 - 1993 review article

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FCC Technician Exam Question Of The Day (T8B03)

Q) Which of the following can be done using an amateur radio satellite?

A) Talk to amateur radio operators in other countries

NJ2X Notes:
Amateur Radio is such a wonderful hobby!  You can even get into satellite communication by simply earning you license.

Thought itself...

In the new era, thought itself will be transmitted by radio. -- Guglielmo Marconi

FCC Technician Exam Question Of The Day (T8A05)

Q) Which of the following types of emission has the narrowest bandwidth?

A) CW

NJ2X Notes:
CW is an abbreviation for continuous wave and is used to transmit morse code.  If you are interested in learning morse code you can tune into the ARRL W1AW daily practice sessions.  We had the pleasure of visiting the W1AW station during the summer of 2012.

FCC Technician Exam Question Of The Day (T8A09)

Q) What is the approximate bandwidth of a VHF repeater FM phone signal?

A) Between 5 and 15 kHz

NJ2X Notes:
Some people find the term, "FM phone" a little confusing when first encountered.  In amateur radio, you are using FM phone when you are speaking into a microphone while transmitting using the FM mode. 

The bandwidth of an FM signal varies with the signal's modulation.

The American engineering genius Edwin Armstrong invented frequency modulation (FM) radio.  Armstrong presented his paper, "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation", to the New York section of the Institute of Radio Engineers on November 6, 1935.

FCC Technician Exam Question Of The Day (T8A03)

Q) Which type of voice modulation is most often used for long-distance or weak signal contacts on the VHF and UHF bands?

A) SSB

NJ2X Notes:
SSB has a distinct performance advantage over AM and FM for long-distance and weak signal voice contacts.

FCC Technician Exam Question Of The Day (T8B10)

Q) What do the initials LEO tell you about an amateur satellite?

A) The satellite is in a Low Earth Orbit


NJ2X Notes:
LEO (Low Earth Orbit), is generally defined as an orbit below an altitude of 2,000 kilometers (1,200 mi).  Given the rapid orbital decay of objects below approximately 200 kilometers (120 mi), the commonly accepted definition for LEO is between 160 kilometers (99 mi) and 2,000 kilometers (1,200 mi) above the Earth's surface.

FCC Technician Exam Question Of The Day (T8B08)

Q) What is meant by the statement that a satellite is operating in "mode U/V"?

A) The satellite uplink is in the 70 cm band and the downlink is in the 2 meter band

NJ2X Notes:
70 cm is considered UHF while 2 m is considered VHF.  Hence, the U/V designation indicating UHF (70 cm) / VHF (2m).

FCC Technician Exam Question Of The Day (T8A07)

Q) What is the primary advantage of single sideband over FM for voice transmissions?

A) SSB signals have narrower bandwidth

NJ2X Notes:
SSB = Single Sideband

SSB signals occupy less bandwidth than FM or AM signals.  This makes SSB more effective for long distance and weak signal work.