Your Mileage Will Vary
by Harold Ort, N2RLL
Today it seems like those fast-talking announcers are everywhere on radio and TV. They brim with disclaimers, letting us know that “past performance is no guarantee of future earnings,” or some such nonsense. Like we don’t know that. Then there’s the fine print now read aloud by announcers in the car commercials: “When you walk in the dealer’s showroom all bets are off regarding what you just heard in this 60-second spot.” And the epitome of disclaimers: “Hey, your actual cost of leasing this vehicle will vary—a lot, actually—from the low-ball estimates you just heard in this commercial.”
You and I have known since grade school that there’s little real truth in most advertising claims. The concept is pretty simple, really: companies pay big bucks to the media to air or print their messages, and they control the content (within reason, of course). And what self-respecting media type isn’t going to take their money?
Over the years, though, I’ve found a great difference between the “claims” made by manufacturers who advertise in most of the mainstream media—whether it’s vehicles, food, travel, etc.—and those made in our radio hobby media. Frankly, there’s very little misleading or half-truths out there in Radioland about our antennas, radios, and accessories. I know many hobbyists who think that some manufacturers’ claims about antennas, in particular, are a bit unusual, so to speak; but for the most part our radio goodies are advertised in a truthful, professional manner when it comes to what they’ll do and not do.
Think about it for a moment. We are—to paraphrase one non-radio commercial here in the New York metro area says about clothing—“educated consumers.” There really isn’t much that could be stretched or massaged to give the illusion of something radio being light-years better or more powerful than it is in reality.
You and I know this is especially true when it comes to transceivers. The specs speak for themselves and, unlike mainstream consumers, we’re likely to actually compare specs on sensitivity, selectivity, audio output, cable shielding, battery capacity and use, plus a multitude of items that largely go unnoticed by most general consumers. The same holds true, I suppose, for other hobbies, from archery and track to bird watching and amateur astronomy. Claims about a telescope’s optics and power are carefully scrutinized and, moreover, understood by those in that hobby.
What’s troubling to me, though, are the claims
mainly directed at consumers when it comes to the range of those small FRS
or GMRS transceivers, you know, the handheld variety that can be purchased
in department store chains and on the Internet. Depending on the
manufacturer and model of walkie-talkie, there are outrageous claims of
anywhere from three to a whopping 17 miles of coverage! Keep in mind
they’re talking about non-repeater use, simplex that is, of units that
include some GMRS frequencies. But even with the higher power allowed by
GMRS, you’re not going to get 17 miles between like units in any world
I’ve visited recently!
News, Trends, And Short
by Harold Ort, N2RLL, Editor, and D.
WorldSpace-South Africa may be forced to ditch its plans to offer satellite radio services to local consumers unless it amends its shareholding to meet the regulatory requirements or it receives an exemption from the government. WorldSpace SA is a wholly owned subsidiary of Nasdaq-listed WorldSpace group.
According to section 64 of the Electronic Communications Act, “a foreigner may not, whether directly or indirectly, exercise control over a commercial broadcasting licensee; or have a financial interest or an interest, either in voting shares or paid-up capital, in a commercial broadcasting licensee exceeding 20 percent. Not more than 20 percent of the directors of a commercial broadcasting licensee may be foreigners.”
The clause has been carried over into the new Electronic Communications Act, which came into effect in August, from the old Independent Broadcasting Act. WorldSpace founder Noah Samara, who was in South Africa recently, said regulatory uncertainty was an impediment to the group as it needed to aggressively roll out the services. He said there was no indication why the license would not be awarded.
WorldSpace group did not reveal how many
subscribers it has in South Africa, where it offers 40 radio stations,
satellite radio receivers for homes, and plans to negotiate with local car
manufacturers so that the services can be installed in cars.
The International Press Institute (IPI) has
condemned the jamming by the Zimbabwe government of the mediumwave signal
of the London-based SW Radio Africa. The IPI says that it believes the
jamming is coming from the broadcasting center at Pockets Hill, rather
than ZBC Gweru, which has previously jammed SW Radio Africa on the
shortwave band. It is widely believed that the Chinese government has
provided the Zimbabwean government with the technology that allows the
signal of private radio stations to be jammed inside the country.
Digital TV Update: What’s In Store For You
That New DTV Picture Is Awesome, But There’s A Catch
by Harold Ort, N2RLL
Many Americans are still living in the analog world. In some ways, I suppose, I’m one of them. Our TV is still of the analog variety, even though we “just” purchased it in 2000. Sure, we Americans have our digital high-tech cell phones, computers, and cameras, but when it comes to TV, well, not everyone is on the bandwagon. And not all of our nation’s television stations are either—at least not yet. That’s okay, though. Contrary what consumer industry PR bobbleheads would have you believe, not everyone runs out to get the latest and greatest digital electronic device after hearing about it on the evening news or being wowed by an ad. That includes the new digital TVs, or DTVs.
But that’s all changing by mid-February 2009!
People Get Ready
To make the process move a bit quicker and turn over 60 MHz of spectrum to commercial and public safety users, the government mandated February 17, 2009, as the magic date for broadcasters to turn over those frequencies, after which they’ll be auctioned off to the highest bidder. (Remember, it’s all about money!) Who gets the money, you ask? Who do you think? Uncle Sam. Heaven knows, the federal deficit is so far in the red that even the billions generated will barely scratch the surface in bringing Sam out of debt—again. But that’s part of the reasoning behind the auctions. The rest of the theory is that those frequencies will ease the over-burdened public safety communications systems, providing a more efficient use of spectrum, especially now with the nation “at war” for the coming years. Time will tell, of course.
In the meantime, Congress gave the FCC
authority to begin the auction process by the end of February 2008. What
does all this mean to consumers regarding televisions? You get a choice
(sort of): You can get an additional top-of-the-set box or a new TV
that’ll receive and decode DTV. The newer TV route is probably the better
choice, frankly, because then you’ve got the DTV decoder built in and
you’re ready to go when DTV comes to your area!
State-Of-The-Art Holiday Ideas!
by Ken Reiss
With the holiday season upon us, it’s time once again to take a look at some scanners and accessories that you might be interested in putting on your wish list for this holiday season.
Of course, topping the wish list for every
radio nut is a new radio, so we’ll start there. Have a look through the
pictures and captions for some suggestions and thoughts. Keep in mind that
many of these units have not been reviewed by the Pop’Comm staff, so we’re
just presenting information based on manufacturer specs. We’ll have more
complete reviews when units are made available to us for testing.
What could be more exciting than opening that
package in the morning to find a shiny new scanner? If you’ve been extra
good, maybe you can hope for one of the cool toys described below.
Uniden has long dominated the world of “pure” scanning, while other manufacturers specialized in communications receivers and ham equipment that also scanned. That’s still true, but increasingly you need the functions of a true scanner to get serious about the hobby, except in isolated (that are getting harder and harder to find anyway). Trunking, which none of the ham or communications receivers offers, is becoming an essential feature for all but the most basic of scanners.
Uniden manufactures under its own name and
provides many of the scanners for RadioShack as well. RadioShack still has
a few models worthy of consideration that are not made by Uniden, but
these days many of the Uniden radios sold by RadioShack are labeled Uniden
and no effort has been made to disguise them.
BC996T—Combining trunktracker IV technology and APCO-25 with 6,000 (yes, six thousand!) channels, the BC996 is the current top of the line. Street price is around $550.
BR330T—A wideband receiver with trunktracking capability! This receiver covers 100 kHz to 1299.995 MHz, so includes the military airband and trunktracker III technology. If you don’t need APCO25 digital this might be the radio to beat. Street price $270.
BC246T—This is a 2,500-channel trunking receiver. For years the BC24X series has been the mainstay of handheld scanning receivers, and the 246 continues the tradition. Slightly older with trunktracker III technology, it’s still a good scanner for many users. Street price around $230.
BC396D—6,000 channels with Trunktracker IV and APCO25 digital, the BC396 represents a state-of-the-art scanner in a handheld package. Street Price around $530.
BC72XLT—If you don’t need trunking and
just want a basic scanner, the 72XLT might be up your alley. Its 100
channels in 10 banks will remind many of us of days gone by, and it comes
in a nice, compact handheld package. Street price $120.
Pre-Winter Rx For Your
Most of us regularly check our homes and vehicles for signs of weather and critter damage, fixing seals around windows and doors, clogged gutters, cracked car door insulation and leaky trunks, but how many of us really take the time to inspect our outdoor antenna systems for signs of trouble? The fact is, not enough, even though the whole system would probably give years more service with a few simple, basic maintenance checks and tweaks before trouble arises.
Right now, before you’re knee deep in
snow (I’m hoping for a generally mild early winter), there’s still time to
get cracking on bringing the outside of your monitoring post or ham shack
up to par. Many instances of degraded signals, antennas toppling in the
wind, critters chewing cables, and water seeping into coax could have been
prevented with some adjustments at the outset. Regardless, you’ve still
got a couple of weeks to spruce up your system before Mother Nature takes
aim this winter and makes you wish you had taken action!
Let’s face it, no one likes to think of replacing aging coax—it’s like taking the car in for a transmission flush and being told your transmission’s wingo-gizmo needs replacing (instant cash out: $400, if you’re lucky). Yeah, you suspected there was a problem three months ago, and it turns out that faint grinding sound you heard on acceleration wasn’t Aunt Beulah’s teeth after all.
The same is true for those weaker BBC signals on 25 meters. Their power hasn’t changed, but your antenna system has taken a beating. Again, you suspected it for a while, but since no one likes getting bad news, you decided to ignore the symptoms.
If your coax or feedline is exposed to the elements it won’t last a lifetime. In reality, it won’t last as long as you might think. Sure, we’d like it if once it went up it would be there to stay, but it’s just not the way life is. Your coax is typically good for three to five years and then, depending on where you live and the quality of the coax, it’s time for a change. At a minimum, it’s time for an inspection.
I know there are folks who have successfully used the same coax and feedline for 10 or more years and never looked back (or outside at the antenna!) since the day it was installed. That’s a big mistake. We wouldn’t like it if those overhead power lines, telephone cables, and poles were only inspected every decade!
We’ll assume you’ve already done the right thing when it comes to the basics of antenna installation (using stainless steel clamps and non-corrosive antenna hardware, proper grounding and lightning/surge protection and making drip-loops). But if you’re putting up a new wire or other skyhook and are ready to think about system maintenance, please read on.
Midland’s 75-822 40-Channel Portable/Mobile CB Transceiver
by Harold Ort
Travelin’ down that long, lonesome highway can sometimes be downright daunting: endless miles, bad weather, worse drivers, and lots of traffic. Factor in some unexpected construction closing the lane you’re in, and those miles can really take a toll on you and your family. Never fear, though, Midland Radio is here—actually there, with you—for those journeys. Of course, I must be referring to Midland’s 75-822 CB. Let’s check it out!
This compact radio is a 40-channel (although
you’ll probably only end up using only a couple of those channels),
full-power mobile Citizens Band transceiver that’s as versatile as it is
easy to use. It comes complete with a small rubber duck antenna that also
allows the radio to be used as a portable walkie-talkie; two battery
cases, one for your six “AA” alkalines, and another for your eight “AA”
rechargeables (an AC wall charger for them is included); and a slide-on
mobile adapter that allows you to use an external mobile antenna and your
vehicle’s 12-VDC cigarette lighter receptacle for power. You also get
complete reception of 10 NOAA All Hazards weather channels.
Good question, glad you asked. The answer is simple: portability and features. Let’s look at how this small wonder operates in a real world environment.
Operation straight out of the box is a cinch.
If you’re going mobile, slide on the adapter, connect your PL-259-equipped
CB antenna, plug the other cord into the cigarette lighter or other
vehicle 12-VDC (negative ground!) receptacle, turn on the CB, and you’re
in business. Changing channels is easy with the side-mounted up/down push
buttons. In fact, it couldn’t be easier! Seasoned CBers will like the
great audio from the small speaker and the good signal reports they get.
The 75-822 easily performs as well as a typical mobile CB (remember, how
yours performs is to a great degree directly related to the quality of
your mobile antenna; good antenna = good results!
Radio Gifts—Perfect To Get Or Give
by Bruce A. Conti
For a non-radio person, trying to find that
special gift for us radio hobbyists can be a challenge. Here are some
interesting gift suggestions sure to please any DXer or broadcast
The Pogo Radio Your Way LX mp3 player/recorder is the perfect digital replacement for those who might still be using analog cassettes for recording DX, music, or other forms of audio (like me). Imagine no more fumbling with piles of cassette tapes, searching for recordings, or dealing with mechanical failures!
The Pogo LX is simple to use. It operates like a cassette recorder, with play, record, fast forward and reverse cue, erase, and volume controls, plus analog stereo line input, an internal microphone, an internal speaker, and analog stereo output. The basic controls are intuitive. You’ll be well on the way to entering the world of digital recording within just a few minutes of becoming familiar with its operation.
The Pogo LX is powered by an internal Li-polymer rechargeable battery, USB port, or a supplied AC adapter. Similar in size to standard mp3 players, the largest dimension measures less than four inches. Prominent features on the front panel are an easy to read 160 x 96 dot matrix backlit LCD screen, a circular up/down left/right toggle, and dedicated push buttons. Controls are ergonomically designed for thumb navigation while it rests in the palm of your hand.
“Never miss another radio program again!” promises the manufacturer of the Pogo LX, which offers an internal AM/FM receiver designed for automatic recording of favorite radio programs for playback at your convenience, thus the name “Radio Your Way.” A timer can be set to record on a daily or weekly basis for as many as 10 separate events.
However, its most useful feature is the stereo
analog line input, a rare find in pocket-sized mp3 players. Whether
recording from the internal receiver or an external source, such as a
communications receiver or CD player, the analog audio is converted to mp3
digital and stored in memory, without the need for a computer.
Furthermore, an expansion slot accepts a 1-GB SD memory card to store as
much as 68 hours of audio per card. The Pogo LX also has a USB port and
supplied cable for when you’re ready to try interfacing to a computer.
Connecting to a Windows XP computer is a piece of cake. Upon making the
USB connection, the computer should automatically recognize the Pogo LX,
and then you can upload files from the Pogo or download mp3s for playback.
A Windows 98SE/2000/ME/XP driver CD is provided just in case your computer
doesn’t recognize the Pogo LX.
THE PROPAGATION CORNER
Winter DX Is At The Door
by Tomas Hood, NW7US
The autumn DX season is in full swing! Listeners throughout the Northern Hemisphere are actively chasing mediumwave (MW) DX of AM broadcast stations from all over North, Central, and South America, and from Europe and Asia. This is the season when it is easier to catch such difficult signals, because now is the time that conditions are most favorable to propagation of this spectrum of the radio frequencies. Shortwave (SW) DX is hot, too, especially on the mid- to low-HF bands from early evening until late at night, and then again from early morning through high noon.
December 21 marks the start of winter. At 0025 Universal Time, the sun will be at its lowest point in the sky in the Northern Hemisphere, making the shortest daylight period of the year for those north of the equator. This is the winter solstice (see http://en.wikipedia.org/wiki/Solstice for more information).
Long hours of darkness make for a less-energized ionosphere. Since the D layer of the ionosphere is less ionized during the winter, MW and SW frequencies are less absorbed, so they can be better propagated by the E and F layers. Additionally, the seasonal decrease in weather-related noise makes it easier to hear the weaker DX signals on the lower frequencies. With thunderstorms few and far between, storm-related static and noise are greatly reduced.
Seasonally, the geomagnetic activity tends to quiet down during the winter months. The most active geomagnetic seasons are centered on the two equinoxes, in the spring and autumn. Combined with the seasonal decrease in geomagnetic activity, the 11-year solar cycle geomagnetic activity is continuing its downward trend toward the end of the current cycle, which will occur sometime at the end of 2006 or during the start of 2007. This results in more stable and reliable propagation on the SW spectrum, especially on the lower frequencies.
December is well enough past the autumnal equinox and the associated peak auroral activity to support transpolar propagation. With this overall reduction of geomagnetic activity and the decrease of radio signal absorption comes more stable high-latitude propagation.
MW DXers enjoy catching broadcast station transmissions from over the North Pole. SW DXing over high-latitude paths can become quite exciting, even though the higher frequency bands might be dead.
THE WIRELESS CONNECTION
Repairing IF Transformers
by Peter J. Bertini
The venerable Hallicrafters S-38 shortwave receiver, briefly mentioned in one of my earliest columns, generated a lot reader feedback from those interested in restoring these perennially popular classics. Many graying hams and SWLs fondly recall saving allowance and paper route money to buy their first set: an S38 receiver!
The Hallicrafters S-38 was an inexpensive beginner’s receiver, and I suspect their current popularity is based more on nostalgia than performance. The original six-tube S38 was introduced in 1946 (one tube was dedicated to the BFO, later models used five tubes with a regenerative IF stage being for CW reception). The S-38E was the last of the line when production ceased in 1961. By that time the S38 was using glass subminiature tubes instead of octal tubes, and like its predecessor, the S38D, produced between 1955 and 1957, the S38E sported a more modern linear slide-rule style tuning dial instead of the half-moon tuning dials used for the main tuning and logging scales on the earlier models.
I’ve been restoring an S38 for a very patient
reader, it’s been one of those projects that never seem to get done,
either getting pushed to the back burner or delayed because of unexpected
problems that crop up as work progresses. This particular S38 had no
shortage of unexpected gremlins. I don’t have a photo of the receiver on
the bench, but I’ll try to take a few for our next column before it goes
back to its original owner.
This particular S38 used a newer style
miniature IF transformer. These transformers are mounted to the chassis
using spring clips (these can be seen in Photo A) and feature inductive
tuning instead of compression mica trimmer capacitors to align the IF
stages. The inductance was varied by the use of threaded ferrite cups that
could be moved over the primary and secondary windings of the transformer.
For Photo B the aluminum cover of one transformer was removed to show the
details of how these devices were made. The ferrite tuning cups are over
the coil windings, hiding them from view. The two polystyrene plastic side
supports are threaded with the same pitch as the threads on the ferrite
cups. As the cups are rotated, they will follow the threaded racks and go
further into, or away from, the coils, adjusting the resonant frequency.
by Rich Arland, W3OSS
Life is a highway
I have always liked that song. The lyrics are indicative of life in general, and we are always moving down life’s highway. So it is with the Arland family. After almost 20 years living in Wilkes-Barre, Pennsylvania, about 100 miles north of Philadelphia in the beautiful mountains of northeastern Pennsylvania, it’s time we pulled up stakes and moved. After 20 years in the U.S. Air Force, moving every two to four years (well, there were a couple of long tours overseas, actually) it was weird not moving for almost 20 years! I actually got “itchy feet” several times, wanting to pack up and hit the road to find new pastures. My wife, Tricia, feels the same way, since she was also in the Air Force.
My time in Wilkes-Barre has yielded quite a nice antenna farm at W30SS (oh, yeah, I changed callsigns a couple of months ago), which I will definitely miss after I move. We found property and a house near Lake Lanier near Buford, Georgia (just north and east of Atlanta), that we want to purchase. It will be our retirement home. There are several problems facing the two of us as we get set to move. Our present house is a three-story, 3,500-square-foot home, with basement, and includes a full-size city lot on the side, in-ground swimming pool, and lots of antennas. Our new home will be around 1,000 square feet and has a whole bunch of restrictive covenants regarding antennas. Needless to say there will be an “adjustment period” when we move.
Our biggest problem is going to be unloading
20 years’ worth of “junque” that we’ve collected in order to transition
into a house that is roughly one third the square footage of what we have
enjoyed in the past.
Then, there’s the antenna situation. My
55-foot tower with the big HyGain TH-7DX tri-band Yagi antenna is a real
pile-up buster and is especially useful when using QRP (under 5-watt)
power levels. I have several wire antennas in the air, hung off the side
of the tower, which acts as an antenna support structure. This allows me
full access to the HF spectrum for both transmitting and receiving. Let’s
not forget the myriad VHF/UHF antennas on poles and chimneys that feed
several scanners and VHF/UHF transceivers at W3OSS. Life at the new place
will be different and that is an understatement.
Ultrasonic-Sensor Wired Weather Station
by Gordon West, WB6NOA
When the weather outside is frightful—and if you pay attention to such things—you may hear about wind cups flying off the outside weather monitor system. If such things pique your interest, you’ll also want to know that the likely cause is not necessarily centrifugal force, but rather flying debris striking the delicate pickup units. And they are delicate; both the wind cup assembly and the wind direction vane must be in perfect balance and absolutely free of debris to read wind speed and wind direction properly. After the devastating hurricanes over the last couple of years, private and municipal weather station managers and meteorologists looked for a major design change to improve the mechanical spinning cups and rotating wind vanes.
A company called Airmar Technology Corporation (www.airmar.com), based in Milford, New Hampshire, has stepped up to the plate. It introduced the WeatherStation PB100, a 12-VDC ultrasonic wind speed and wind direction sensor with zero moving parts—no cups to become damaged by flying debris and no wind vane to get wiped off by flying branches. Apparent wind speed and direction are instead calculated from pulses that are transmitted from the ultrasonic sensors. The air flowing through the wind channel determines how fast the pulses travel, providing the wind speed and direction reading. This is the same principle that has been used for years to measure fluid flows in industrial and medical equipment, as well as to measure apparent hull speed as a boat travels through the water.
“Mariners had the same problem as
meteorologists,” says Mark Reedenauer, product marketing manager for
Airmar. “Old fashioned boat-speed spinning paddle wheels would constantly
get clogged with sea debris and would show erratic operation as gunk built
up on the paddle wheel blades.” He points out that the ultrasonic
measurement of wind speed and direction through the company’s patented
sensor continues to stay accurate even in driving rain. Water molecules
and even thin ice on the blue reflective ultrasonic plate will not affect
Inside the Airmar solid-state sensor is a barometric pressure pickup, relative humidity pickup, solid-state compass (called a fluxgate compass), electronic level, accelerometer pickup, and even an optional GPS sensor.
The weather sensor, weighing only a little
over half a pound, feeds about 30 feet of supplied flexible multiconductor
cable to a small black box that converts all sensor readings over to a
THE POP’COMM TRIVIA CORNER
Radio Fun And Going Back In Time
by R.B. Sturtevant
Q. When was the first football game broadcast?
A. That historic event occurred on
November 18, 1919. Wesleyan was playing New York University in New York
City. Although there was a large delegation from Wesleyan at University
Heights, many students couldn’t make the trip from Middletown,
Connecticut. The authorities at NYU asked Dr. Lee de Forest if he could
help. De Forest was enthusiastic about the project and established a
communications center in the Physics Department of Wesleyan the night
before the game. On game day a newspaper reporter from NYU wrote up the
highlights of the game, and a messenger took the script to a telephone
connected to the de Forest Lab. The lab then broadcast the script to the
Wesleyan Physics Department. To make sure there were no slip-ups the
script was then telegraphed to Wesleyan as a back-up. With that system
students at Wesleyan could follow the game closely.
Q. What part did radio play in the beginning of World War II?
A. Most people consider the beginning of World War II in Europe to be Hitler’s invasion of Poland. With that in mind, remember that Dr. Joseph Goebbels had already used radio extensively to lay down a blanket of propaganda before the troops moved into Austria and Czechoslovakia. Poland was to be no different. Germany had lost a considerable amount of pre-1918 territory to Poland, including the Silesian coal fields and the Danzig Corridor. Particularly painful to Teutonic pride was the Corridor, which split East and West Prussia in two and gave Poland its only link to the sea. Goebbels hammered away at the Poles over the radio concerning these and other indignities.
When the Poles showed no sign of buying into Goebbels tripe, some of Hitler’s SS bullies rounded up a bunch political prisoners and dressed them in Polish Army uniforms. On August 31 the prisoners were taken to the German town of Gleiwitz near the Polish border. The prisoners were shot near the local radio station. The SS then used the station to broadcast a pro-Polish/anti-Nazi tape that had been prerecorded. The recording even included battle noise of the avenging German Army driving the invading Poles back across the border. The dead political prisoners added the element of truth to the whole operation. This “insult” to German sovereignty and pride could not go unchallenged. The next day, September 1, 1939, the German Army invaded Poland at 6 a.m.
by Kirk Kleinschmidt, NTØZ
As I write this month’s column, torrential rains have inundated much of Kentucky, with the Louisville area being hit particularly hard. Some spots saw as much as 4-1/2 inches of rainfall in a single hour! Needless to say, flooding was —and is—an ongoing problem. And then there’s Katrina, the aftermath of which we’re still struggling with. And the other day, the nation’s heartland saw 40-plus tornadoes touch down.
Whether we live in an era of global warming, prophetic times or just one of those decades, the power has been going out a lot these days, and there’s no end in sight. And when the power does go down, hams are still somehow expected to remain on the air, and often form a critical—or lone—link to the outside world.
Battery power, backed by solar and wind
generation, can keep comms running for the initial response to most any
emergency, but sooner or later someone’s gotta fire up a gas- or
diesel-powered generator. This month’s column focuses on generator power
and how to use it safely.
Basically, portable power generators are “backward” motors. They convert mechanical energy (shaft rotation) into electrical energy. Think of them as 120-volt “automobile-style” alternators that happen to be powered by lawnmower engines.
For most generators, as the engine spins an AC generator (alternator), the voltage and frequency of the AC output depend on the rotational speed of the engine. If the engine is running too fast or too slow, the unit’s voltage and frequency will be high or low, accordingly. If the engine speed is correct, voltage and frequency will approximate the power supplied by the AC mains—a 120-VAC sine wave with a frequency of 60 Hz.
There are several electronic and mechanical methods used to keep voltage and frequency values stable as engine speeds vary. Many gens use mechanical “governors” to keep the shaft turning at the about the right speed. If the shaft slows down (because of increasing generator demand), the governor “hits the gas” to bring the shaft speed up to par (and vice versa). Sophisticated units also have electronic regulators to help keep things steady near 120 volts/60 Hz.
by Joe Cooper
On the morning of December 7, 1941, American code breakers uncovered startling information in some apparently routine Japanese diplomatic traffic: Japan had apparently given up on achieving a diplomatic solution to the growing problems it was having with the United States, and war seemed to be the only logical outcome.
The news quickly reached U.S. Army Chief of Staff General George Marshall, who was then faced with a serious decision. It was obvious that the new information needed to be disseminated as quickly as possible, but the question was which method of communications to use. Voice was the obvious choice for speed, but Marshall had serious misgivings about using this method of communication.
The only secure method the United States was using at that time was an analog device maintained by Bell Labs, known as the A-3 voice scrambler, which had been developed in the 1930s. The A-3 system was relatively simple, basically mixing the information signal with a second one containing noise, making it all but impossible to understand. This noise was removed from the signal at the receiving end by mixing it with a new signal containing identical noise, subtracting (or canceling) out the original noise.
Unfortunately, one or more German engineers were involved in the A-3 project during its development and understood the theory behind the technology. Therefore, when World War II began Germany knew exactly how the scrambling technology worked (though in reality it had been far from secret in the first place). As a result, Deutsche Reichspost, the government agency responsible for all telephone and telegraph transmissions in Germany and occupied Europe, developed effective methods for breaking the A-3 system by the early 1940s. Using an interception site located on the Dutch Coast, German intelligence was able to listen in to extremely sensitive military and diplomatic communications of the Allied forces, including those taking palace between President Franklin Roosevelt and Prime Minister Winston Churchill.
Since the Japanese were allied with Germany,
Marshall was certain that they too had access to the technology needed to
crack the A-3 system. So rather than using voice transmission, he opted
for a coded radiotelegraph—and the message arrived after the sneak attack
on Pearl Harbor had begun.
UTILITY COMMUNICATIONS DIGEST
The Coming Winter:
by John Kasupski, KC2HMZ
If the old adage that “time flies when you’re having fun” is really true, then the year 2006 must have been a real treat. I find myself wondering how it can possibly be over already. It just doesn’t seem as if a whole year has already gone by, yet here it is, December again.
Since December finds us at the height of the holiday season, I’d like to extend to everyone my best wishes to you and yours for a very safe and happy holiday season. Also for the best of luck in 2007, whether it’s at your radio equipment or away from it.
The coming of the holidays isn’t the only good news for radio hobbyists. Despite the arrival of snow, ice, and biting winds to the northern latitudes, Mother Nature has some good news for many of us as well. While most thunderstorm activity in June, July, and August occurs 10 to 20 degrees north of the equator, during December, January, and February most thunderstorm activity is 10 to 20 degrees south of the equator. This puts thunderstorm activity, and the resulting static crashes we hear on our HF receivers during a thunderstorm, the farthest away from the northern hemisphere, promising an improvement in conditions on the lower bands.
In fact, if you’re one of those who are fortunate enough to have a directional antenna, this places most thunderstorm activity off the back of the directional antenna for the major ham/SWL population in North America, Europe, and Japan. Furthermore, there’s also a seasonal decrease in geomagnetic activity during December, which is not as marked as the minimum yearly activity that we see during June and July, but enough to contribute to a noticeable increase in the number of loggings reported on the lower bands.
In addition, the longer hours of darkness give
us a sharp decline in D-layer signal absorption on the lower bands. The
improved conditions on the lower bands come at the expense of somewhat
less favorable conditions on the higher bands, but by tuning low you can
take best advantage of the changing conditions and continue to put
interesting catches in your logbook.
Another old adage, one that comes to us from
ham radio lore, holds that the efficiency of an antenna system is
inversely proportional to the weather conditions prevailing during the
time of the installation. Translated into less technical terms, that means
the worse the weather is on the day you put up an antenna, the better it
supposedly will perform. If that’s the case (and there seems to be no
shortage of anecdotal evidence to support the idea, though empirical
evidence is somewhat more difficult to come by), then we should, I guess,
all be gearing up to perform major overhauls of our antenna systems…in the
dead of winter!
Solomon Islands: Thirty-Five
by Harold Ort, N2RLL, Editor
This archipelago nation of nearly 1,000 islands is home to about 550,000, 2005 est. including people of Melanesian, Polynesian, and Micronesian descent. English is the official language, though few of the population speak it—in an area only about the size of Maryland, there are roughly 120 other languages spoken!
Located in the South Pacific about 6,000
thousand miles from California, the Solomon Islands are indeed remote;
even Hawaii, to the northeast, is 3,555 miles distant. What many consider
a beautiful paradise, others think of as a nation barely “in check”
because of recent political and ethnic unrest. “The Solomons” is certainly
a place of wondrous beauty; but remember, beauty can be short lived and
sometimes is only surface-deep.
Actually, the Solomon Islands are probably best known for the battles fought there during World War II. Within six months of the bombing of Pearl Harbor, the Japanese expanded their empire extremely quickly, and in doing so became overconfident in their quest. Suddenly, in May 1942, in the Battle of the Coral Sea their over-confidence was cut down as they attempted to move toward the Solomon Islands and New Guinea. For the “boots on the ground” the Solomons was anything but paradise (if ever soldiers experienced weather that could be called hot, wet and humid, the Solomon Islands gave it to them).
With limited resources, Admiral Chester Nimitz attacked the island of Guadalcanal in the Solomons in deplorable battle conditions. The official U.S. Army history report says that for every two soldiers and Marines lost in battle, another five were lost because of disease. The Marines landed on August 7 and faced little opposition, quickly taking an airfield. But that victory on Guadalcanal was the easiest, by far.
GLOBAL INFORMATION GUIDE
Voice Of Armenia Shuts Down, Plus Radio Japan’s World Shrinks
by Gerry L. Dexter
Here we are nearly at the end of another year of shortwave listening. And, aside from wondering how the heck it managed to go by so fast, I have to say that the shortwave picture at the close of 2006 is not a very pretty one. It’s as if there were a “bad news of the month club” that, like it or not, we’ve been forced to join. And there’s no card to return to indicate you don’t want this month’s selection!
The latest broadcaster to have pushed the countdown button to self-destruct is the Voice of Armenia, which was scheduled to close down for good at the end of October.
And Uzbekistan’s Radio Tashkent International,
which discontinued operations a few months ago, appears to be nearing a
shutdown of their transmitter site at Dushanbe, leaving that avenue
unavailable to its several clients, Radio Nederland among them.
Radio Australia is also moving towards an
increased focus on TV, as well as experimenting with digital broadcasts.
On the other side of the ledger, a semi-major
broadcaster is about to experience a serious upgrade in its facilities.
Nigeria is getting a whole new broadcasting center for its high-frequency
transmissions. The Voice of Nigeria will be adding at least one new 250-kW
transmitter capable of DRM use, with two more to be added later, complete
with a new building to house them—even a rotatable antenna configuration.
You have to hope these improvements will include a fix of the modulation
problems VON has suffered from for so long. This new facility will be
located near the Nigerian capital, Abuja. At present VON has a transmitter
there operating on 7275 from around 0530, though it hasn’t been heard all
that well. Meanwhile, other FRCN (Federal Radio Corporation of Nigeria)
regional outlets, including Kaduna-4770, have had their correspondents
pulled out and transferred to the Abuja headquarters. This move apparently
was largely politically motivated.
All About Wire
by Bill Price, N3AVY
Good morning, class. Today’s lesson will be about wire. What’s that? You there, in the back row with your hand up—you say it’s not much of a subject?
Well, yes, in a way, you’re right. It’s not much more than stretched copper. Sometimes tinned, sometimes coated with lacquer or plastic insulation. Sometimes solid, sometimes stranded. There’s coaxial wire with braided shield, or twisted shield, and sometimes it even has an additional foil shield. Hardline has solid core or tubular center with solid corrugated shield, Eventually, you get to rigid coax, which can be six inches in diameter! It’s hardly “wire” at all.
There is an entire “school” of highly overrated, overpriced cables for moving sound from one point to another. It has spawned an entire industry for people who don’t realize that good old “zip-cord” is more than adequate for absolutely any home audio application. P.T. Barnum was right. This way to the egress.
But today’s lesson is about the simpler types of wire that we’re more likely to encounter in our daily lives as hams and other radio hobby people. Most interesting is the power that wire has over a person trying to work with it. Picture yourself sitting by a body of water late at night while all your friends are fishing, catching enormous tunas or bass or whatever it is that’s biting in the local stream. And while they’re all filling their ice chests with next week’s delicacies, you’ve got a tangled mass of monofilament resulting from a backlash and you’re sitting in the dark wondering if this might be a good time to change religions or just go to an all night Mega-Lo-Mart (forgive me, friend to remain nameless) and just buy a new reel.
That’s how it was when I decided to save money on a dipole.
It was actually more than a dipole; it was several dipoles with a common feed point. Some called it a fan, others called it a “crow’s foot,” but whatever you call it, it was damn difficult to unwind and split one dipole from that nice dollar-store speaker wire (which really is good enough for a medium-power dipole). But I was sure I could make this entire acre’s worth of wire into an antenna in the living room of an apartment and sneak it out across a common driveway in the dark of night, and then fasten it to such forbidden structures as the local police station, two neighbor’s trees, and an unused utility pole.