Posts

Showing posts from November, 2013

Antenna Safety. Post #246

In the excitement of designing, building, and erecting my "homebrew" wire antennas, I've often neglected to consider important safety issues which could affect the location of my antenna and perhaps save my life.
A few years ago, I erected a vertical antenna which gave me excellent service until a lightning strike turned my work of art into a mess of shattered fiberglass, pvc pipe, wire fragments, charred coaxial cable, and a severely damaged ego.  Fortunately, I had disconnected the feed line from my shack and had it connected to a ground rod.

Ever since that lucky escape from Mother Nature, I've had a firm respect for the weather and "Murphy's Law" (whatever will go bad will fail at the most inconvenient time).

Over the course of my amateur radio "career", I've followed a few basic guidelines to erecting antennas, whether they be commercially bought or built from my own resources.

PLAN AHEAD

I know this sounds pretty basic, but thoroug…

Simple Ham Radio Antennas: The sloping 30 through 10 meter delta loop. Post #245

How would you like to build a simple, effective antenna for 30 through 10 meter coverage with some gain over a dipole at a moderate cost?  The answer is as simple as designing, erecting, and using a sloping delta loop antenna designed for 30 meters and fed with 450 ohm ladder line into a 4:1 balun connected to a sturdy antenna transmatch.  The ladder line will permit you to cover frequencies between 10.100 MHz through 29.7 MHz with low SWR.  You can also design the antenna for 30 meter use only by feeding the antenna with 50 ohm coaxial cable in conjunction with a 1/4 wavelength matching section made of 75 ohm coaxial cable.  The latest ARRL Antenna Book has more details on how to make the matching section should you decide for that option.

Now that I have more room for my expanding "antenna farm" at my new home site in the Puna District of Hawaii Island, I can set aside some space for antenna experiments without worrying about HOAs, CC&Rs, or unsympathetic  neighbors. …

Simple Ham Radio Antennas--the 40 meter NVIS loop. Post #244

In this age of natural and man made disasters, it's important to have back up equipment, antennas, and power available during periods of emergencies.  A set of homebrewed wire antennas can keep you on the air when your beam or tower have been damaged by forces beyond our control.

One of the best standby antennas is the NVIS antenna, which, because of its portability and ease of operation, can be tucked away in a convenient spot for future use.  NVIS (near vertical incident skywave) antennas are perfect for local or regional use out to about 300 miles/480 kilometers.  NVIS antennas are close to the ground (between 1/10 to 1/5 wavelength above ground) and shoot most of their signals straight up.  Sometimes called "scatter beams" or "cloudwarmers", these antennas can cover a wide area (especially mountainous terrain) with little power.

A NVIS antenna can be configured in several ways, including low-level 1/2 wavelength dipoles or low-level full wave loops.  If …

Simple Ham Radio Antennas: The slanting 80 meter delta loop. Post #243

One of the joys of moving out of my cramped quarters at Laupahoehoe to more spacious property (1 acre) in the Puna District is the ability to erect some decent antennas.  For most of my 36 years as an amateur radio operator, I've had to "make do" with compromise antennas that often performed poorly compared to full-sized antennas.  Thanks to 450 ohm ladder line, a sturdy W9INN 4:1 balun, and a trusty Drake MN-4 antenna transmatch, I've been able to get some excellent multi band contacts with the 40 meter inverted v in the backyard and the 40 meter loop under my post and pier house.  I can't complain.  These antennas have done a good job with my older equipment in the shack.

Once I complete the slow move to my new home in the Orchidland Estates, I won't have to worry about lack of space for antennas and any ground systems I might install.  To date, I erected the following antennas at the new QTH:

A 135 ft/41.15 meters long horizontal dipole (the classic "…

An Emergency "Go Kit" for the home station. Post #242

A few days ago I described the simple emergency "go kit" installed in my Honda Odyssey van.  This simple station has served me well for both portable and Field Day use.  I have no doubt the system will work during emergencies.  In fact, I've set up my "go kit" station in the backyard with excellent results using a  simple inverted v antenna and an under-the-house 40 meter loop on my lot.

Although this arrangement worked very well, I wanted to make a special "standby" station in case my main station didn't work for some reason.  Fortunately, I had a few spare rigs in the shack, and I decided to employ them in my home emergency station.

My main amateur radio station has the following equipment (most of it old, but totally functional):

One Ten Tec Argosy II transceiver and Ten Tec power supply.  I can run this rig off the electrical mains or with a solar panel/deep cycle marine battery combination.

One Drake MN-4 antenna transmatch.  I can use 450 …

A simple "Go Kit" for emergencies. Post #241

In light of the recent natural disaster in the Philippines (super Typhoon Haiyan), it might be useful to review just how prepared we amateur radio operators are for natural and man-made disasters.  Many of the hams running emergency traffic in the Philippines are using low powered rigs and simple antennas to maintain a communications lifeline in devastated areas of the Central Philippines.  Perhaps, we should do the same.

In my 36 years as an amateur radio operator, I've always followed the policy of having spare equipment, antennas, parts, tools, and standby power should an emergency arise.  While those of us living in Hawaii aren't prone to the series of disasters befalling southeast Asia, we do get our share of hurricanes, severe thunderstorms, earthquakes, and, occasionally, tsunamis.  Most hams living in the 50th state are prepared to provide emergency communications should the need arise.

It's prudent to have an emergency radio system installed in your home as well …

Super Typhoon devastates the Central Philippines. Post #240

Today, our prayers are with the residents of the Central Philippine Islands, who are just starting to recover from the devastation of super typhoon "Haiyan."  According to Ramon Anquitan (DU1UGZ) of the Philippine Amateur Radio Association, amateur radio operators in that island nation are providing emergency communications links to the government, as well as handling health and welfare traffic from impacted areas, such as Tacloban City--one of the hardest hit areas southwest of Manila.

Although the Philippine Red Cross says there are at least 1,000 dead from the devastating storm, reports from the Associated Press and Radio Australia put the dead and missing total somewhere near 10,000.

Typhoon "Haiyan" was an especially strong storm system with winds exceeding 175 mph (280.5 km/hr) in some areas.  Storm surge, heavy rain, and flooded rivers have destroyed thousands of homes and damaged hundreds of businesses in the Cebu area.  Government officials have sent  rel…

My favorite Amateur Radio antenna books. Post #239

If you've been an amateur radio operator for any length of time, you probably have a good collection of parts, books, magazine articles, wire, coaxial cable, connectors, and basic tools to support your hobby.  This "junk box" is part of our amateur radio tradition...making do with what you have on hand.  I'm no exception.  In my 36 years as a licensed amateur radio operator, I've accumulated a wide collection of items, ranging from books to spare rigs.  Of course, the collection circulates a bit through trades, upgrades, giveaways to newly licensed hams, and, finally, to the recycling station.

One of the things I rarely sell or giveaway is my growing collection of books related to Amateur Radio and Amateur Radio antennas.  Many of these volumes were bought when I was newly licensed or successfully upgraded my license.  Nowadays, the task of assembling an Amateur Radio library is easier, thanks to the internet, Amateur Radio-related websites, and the outstanding …