NJ2X

Equipped with his five senses, man explores the universe around him and calls the adventure science. — Edwin Powell Hubble

All you need in this life is ignorance and confidence, and then success is sure. -- Mark Twain

The empires of the future are the empires of the mind. -- Sir Winston Churchill

Cast your eyes toward the heavens this December 13-14, 2014 for a peak at the Geminids meteor showers.

Good DX and 73, NJ2X

Get your facts first, and then you can distort them as much as you please. -- Mark Twain

An investment in knowledge pays the best interest. -- Benjamin Franklin

We must beware of trying to build a society in which nobody counts for anything except a politician or an official, a society where enterprise gains no reward and thrift no privileges. -- Sir Winston Churchill

America's quiet warriors are the legion of ham radio operators, 700,000 of them, who are always at ready for backup duty in emergencies – amateur, unpaid, uncelebrated, civilian radio operators, during and after floods and fires and tornadoes. After the 9/11 attacks, hams were indispensable in reuniting friends and families. Most recently it was they who expedited the search for debris after the Columbia Explosion , and right now, at this moment, they are involved in homeland security to a greater degree than you would want me to make public. — Paul Harvey

We have been enjoying the ARRL Centennial QSO Party since getting our station on the air August 15, 2014 after being off the air since the beginning of January 2014.  You can check your current standing on-line.  It is fun to watch your statistics grow.  Wish we would have been able to operate all year - would have made a big difference score-wise.

Working the W1AW portable stations is really fun.  Planning to pick up as many as possible between now and the end of the year.  NJ2X is in the top 32% for the Centennial Points Challenge (left) and the top 19% on the W1AW portable stations leader board (right).



Good DX and 73, NJ2X

On this day in science history, November 1st, 1878, the first telephones are installed on the trading floor of the New York Stock Exchange.




Good DX and 73, NJ2X

Do not worry about your difficulties in Mathematics. I can assure you mine are still greater. — Albert Einstein

Hams worldwide were having a great time today in the CQ WW SSB Contest (2014.10.25) on HF until about 17:00 UTC when a massive X-class solar flare caused radio blackout worldwide.  The sound of all the HF bands closing down was remarkable.  The only HF communication remaining active was via ground wave propagation.  The HF radio blackout started to lift about 18:30 UTC with the re-opening of the 10m and 12m bands and then the other bands over time.



So what does X3.1 solar flare mean?  Solar flares are classified as A, B, C, M or X according to the peak flux in watts per square meter (W/m2) X-rays near Earth, as measured on the GOES spacecraft.
ClassificationPeak Flux Range picometre (W/m2)

A< 10−7B10−7 - 10−6C10−6 - 10−5M10−5 - 10−4X10−4 - 10−3Z> 10−3 Within each class there is a linear scale from 1 to 9.n (apart from X), so an X2 flare is twice as powerful as an X1 flare, and is four times more powerful than an M5 flare.  X class flares up to X28 have been recorded.

Good DX and 7…

Anyone who has had actual contact with the making of the inventions that built the radio art knows that these inventions have been the product of experiment and work based on physical reasoning, rather than on the mathematicians' calculations and formulae.  Precisely the opposite impression is obtained from many of our present day text books and publications. — Edwin Armstrong

Edwin H. Armstrong invented the regenerative circuit, superheterodyne circuit, superregenerative circuit, and FM radio. 

Simplicibus itaque verbis gaudet Mathematica Veritas, cum etiam per se simplex sit Veritatis oratio. (So Mathematical truth prefers simple words since the language of truth is itself simple.) — Tycho Brahe

There seems to be an app for nearly everything. Are you working on learning the international phonetic alphabet? Well it turns out there is an app for that too - the Phonetic Alphabet Viewer available on the iPhone. This is a very simple app that provides the student with an interactive visual method of learning. Simply touch a key to see the phonetic equivalent spelled on the screen instantly. The price is right too - FREE. The app also has solid customer ratings which is often a good indicator of product quality.

Go through the alphabet in sequence saying the phonetic equivalent in your head. Then press the letter to check if you have it correct. When you find a letter that you struggle with pause for a moment to repeat the phonetic three times while focusing on the word.

You will be speaking the international phonetic alphabet in no time. Practice, practice, practice, ...

Good DX and 73,

NJ2X (November Juliet Two X-Ray)

We can scarcely avoid the inference that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena. — James Clerk Maxwell

Success is going from failure to failure without the loss of enthusiasm. -- Winston Churchill

The first baby monitor was the "Radio Nurse" in 1937.  This device was inspired by the Lindbergh tragedy.  It is a beautiful design by Isamu Noguchi though technically the design was prone to problems (distortion and interference).



Good DX and 73, NJ2X

The California QSO Party 1600 UTC October 4, 2014 to 2200 UTC October 5, 2014

Please see http://cqp.org/ for all the rules and details.  Hope to work you during the event.

From California, Good DX and 73, NJ2X

Be sure to take a look at the night sky.  The Draconids meteor show will return to visit October 7-9, 2014.

Good DX and 73, NJ2X

It is said that a picture is worth a thousand words.  Pictures are also a great way to help learn the international phonetic alphabet.  Word association and visual images help promote retention in long-term memory.  Have fun!


Good DX and 73, NJ2X  (November Juliet 2 X-ray)

Be courageous. I have seen many depressions in business. Always America has emerged from these stronger and more prosperous. Be brave as your fathers before you. Have faith! Go forward! -- Thomas A. Edison

Being busy does not always mean real work. The object of all work is production or accomplishment and to either of these ends there must be forethought, system, planning, intelligence, and honest purpose, as well as perspiration. Seeming to do is not doing. -- Thomas A. Edison

Our greatest weakness lies in giving up. The most certain way to succeed is always to try just one more time. -- Thomas A. Edison

Thunder is good, thunder is impressive; but it is lightning that does the work.-- Mark Twain

Science is what we know, and philosophy is what we don't know. — Bertrand Russell

The aims of scientific thought are to see the general in the particular and the eternal in the transitory. ― Alfred North Whitehead

In the conditions of modern life the rule is absolute, the race which does not value trained intelligence is doomed. ― Alfred North Whitehead

“Nature is probably quite indifferent to the aesthetic preferences of mathematicians.” ― Alfred North Whitehead

It that time again, the Perseids meteor shower will return August 10-13, 2014.  Be sure to keep an eye on the sky.

Good DX and 73, NJ2X

On a recent trip to Disneyland we spotted this rather adventurous looking listening post in line for the Jungle Cruise attraction.  We really loved the way the canoe has been transformed and repurposed as a bookshelf with all manner of adventurous paraphernalia including two vintage shortwave radios.

The radio inside the canoe-bookcase with the black cabinet is a Hallicrafters model S-53A general purpose receiver covering 540 Khz to 54.5 Mhz in 5 bands (circa 1951 to 1959).  Like its contemporaries, the S-53A was designed to use tubes including the 6BA6 (mixer, 1st & 2nd IF amplifiers), 6H6 (detector), 6C4 (oscillator), 6K6GT (AF output), 6CS7 (AF amplifier, BFO), and 5Y3GT (rectifier).  The original price when this radio was introduced in 1951 was $89.50.  At nearly 20 lbs, this would have been a tough piece of gear to lug around the jungle (other than on a boat).

The grey radio on the desk is a National Radio model NC-125 receiver (circa 1950 to 1956).  This AM/CW/SSB radio recei…

“Not ignorance, but ignorance of ignorance is the death of knowledge.” ― Alfred North Whitehead

It is curious to reflect on how history repeats itself the world over. Why, I remember the same thing was done when I was a boy on the Mississippi River. There was a proposition in a township there to discontinue public schools because they were too expensive. An old farmer spoke up and said if they stopped the schools they would not save anything, because every time a school was closed a jail had to be built.  It's like feeding a dog on his own tail. He'll never get fat. I believe it is better to support schools than jails. -- Mark Twain

Keep your eyes on the sky July 29-30, 2014, the Delta Aquarids meteor showers will have returned.


Good DX and 73, NJ2X

"Any intelligent fool can make things bigger and more complex... It takes a touch of genius --- and a lot of courage to move in the opposite direction." - Albert Einstein

"Imagination is more important than knowledge." - Albert Einstein

“To punish me for my contempt for authority, fate made me an authority myself.” ― Albert Einstein

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




NJ2X Kindle Edition is now available.

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 …

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.

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…

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. 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

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.

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.

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.

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.

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.

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.

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. 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

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


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.



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.

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.

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.

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.

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.

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…

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

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.

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.

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.

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.

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.

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.

This is another is a series of articles about the Azden AZ-61 FM 6m HT.  In researching the AZ-61, we ran across a vintage 1993 review article by Gordon West originally published in 73 magazine.  This article is available on-line at archive.org.

73 Review - Azden AZ-61 6m FM Transceiver by Gordon West WB6NOA


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 - rebuilding the battery pack
Azden AZ-61 6m FM HT - Tip #5 - how to reset the radio
Azden AZ-61 6m FM HT - Tip #6 - Automatic Power-Off
Azden AZ-61 6m FM HT - Tip #7 - VFO Mode
Azden AZ-61 6m FM HT - Tip #8 - Frequency Step
Azden AZ-61 6m FM HT - Tip #9 - Scanning
Azden AZ-61 6m FM HT - Tip #10 - Dual Watch
Azden AZ-61 6m FM HT - Tip #11 - Battery Saver Azden AZ-61 6m FM HT - Tip #12 - Optional Accessories

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.

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

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.

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.

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.

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.

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).

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.

This post is in a series regarding the 1990's vintage Azden AZ-61 6m FM HT.


So you have dusted off  your Azden AZ-61 6m FM HT and powered it back to life.  Congratulations for giving this neat old radio a go!  One of the things you may have noticed when pressing buttons is an annoying, "beep" after each key press.  The good news is that the beep noise can be toggled off and on easily (if you know the trick).
How to toggle off and on the key press beep Step 1) Press and hold the "FUN" key while powering the radio on.


Yes, it is that simple.

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 - rebuilding the battery pack
Azden AZ-61 6m FM HT - Tip #5 - how to reset the radio
Azden AZ-61 6m FM HT - Tip #6 - Automatic Power-Off
Azden AZ-61 6m FM HT - Tip #7 - VFO M…

B) Which of the following is true of PL-259 type coax connectors?

A) They are commonly used at HF frequencies

NJ2X Notes:
The PL-259 connector is the defacto standard on HF amateur radio equipment.  The type N connector is technical superior in everyway but is not commonly found on amateur radio equipment.



The Space Elevator will be built about 50 years after everyone stops laughing -- Sir Arthur C. Clarke

Q) Why is it important to have a low SWR in an antenna system that uses coaxial cable feedline?

A) To allow the efficient transfer of power and reduce losses


NJ2X Notes:
A perfect standing wave ratio (SWR) is 1:1.  Higher SWR is the result of an antenna and feedline that do not have matching impedances.  Any SWR greater than 1:1 indicates some of the transmitted energy is being reflected back toward the transmitter.  This reflected energy results in RF energy being radiated from the feedline as heat (an efficiency loss).  In some cases, the reflected energy can even cause damage to the transmitter. 

Q) What is meant by the gain of an antenna?

A) The increase in signal strength in a specified direction when compared to a reference antenna

NJ2X Notes:
Gain is often expressed in decibels (dB).  A theoretical antenna called an isotropic radiator is sometimes used as a reference.  An isotropic radiator is a point source located in free space and radiating equally in all directions.

Q) In which direction is the radiation strongest from a half-wave dipole antenna in free space?

A) Broadside to the antenna

NJ2X Notes:
The strongest radiation from a half-wave dipole is at right angles to the antenna wire. For example, if the dipole wires are oriented so they run to the East and West then the antenna would radiate the strongest to the North and South.

Q) What is a satellite beacon?

A) A transmission from a space station that contains information about a satellite

NJ2X Notes:
Satellite beacon frequencies


Beacon. An amateur station transmitting communications for the purposes of observation of propagation and reception or other related experimental activities.

Q) What type of modulation is most commonly used for VHF packet radio transmissions?

A) FM


NJ2X Notes:
FM stands for Frequency Modulation.  FM is used extensively in VHF and UHF communications.

Take a gander at the Camelopardalids meteor shower tonight.

Good DX and 73, NJ2X

Q) What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna?

A) 112


NJ2X Notes:
The easiest way to handle this question is to memorize the answer.

The Azden AZ-61 6m handi-talkie (HT) can be found from time-to-time at hamfests for a relatively low price.  Buying one without the manual; however, can be a rather frustrating experience since the radio's design is far from intuitive.  This isn't the kind of radio that you can put in your hand and program without looking at a manual.  Almost anyone who has owned one would agree that it is downright difficult to program the AZ-61 (even with the original manual).

After searching the Internet, we discovered that there are rather few resources to guide the manual-less Azden AZ-61 owner in programming the radio.  As a consequence, there are probably more than a few fully functional units out there just sitting on a shelf collecting dust for lack of ability to program.  If you are one of those owners, we prepared this short tutorial on programming the Azden AZ-61 for you.  We hope it inspires you to dust-off your Azden AZ-61 (or snap one up at a hamfest), program a repeater or two,…

Q) What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz?

A) 19

NJ2X Notes:
Electromagnetic waves travel at the speed of light which is 299,792,458 meters per second or for the ease of calculation we can round up to 300,000,000 m/s.  Frequency and wavelength are related and can be determined by the formulas:

Frequency = Speed of Light / Wavelength

or

Wavelength = Speed of Light / Frequency


The easiest way to deal with this question is to simply memorize the answer.

Q) What is a good reason not to use a "rubber duck" antenna inside your car?

A) Signals can be significantly weaker than when it is outside of the vehicle

NJ2X Notes:
Using an antenna on the exterior of the vehicle will dramatically improve both reception and your transmitted signal.  Better to have all that RF outside the vehicle too.

If the presence of electricity can be made visible in any part of the circuit, I see no reason why intelligence may not be transmitted instantaneously by electricity. -- Samuel Morse

Q) How would you change a dipole antenna to make it resonant on a higher frequency?

A) Shorten it


NJ2X Notes:
The key to successfully answering this question is to remember that wavelength gets smaller as the frequency increases.  The physical dimensions of antenna correspond to the wavelength.  So to optimize an antenna for a higher frequency you need to shorten the antenna's size (and wavelength).

The old carpenter's adage, "measure twice, cut-once" doesn't quite work when shortening an antenna for a particular frequency.  That is because antennas are complex and cutting them exactly to spec or formula does not assure an antenna will behave at the desired frequency.  A more appropriate adage might be, "measure the length twice, trim a little, measure the resonance and SWR, repeat as necessary".