Posts

Hawaii Island Hams help during tropical storm warning. Post #217

Today at 1700 hours local time, The National Weather Service downgraded Tropical Storm "Flossie" to a tropical depression.  The weakened storm swept over Hawaii Island, leaving heavy showers, gusty winds, high surf, and power interruptions in its wake. Thankfully, no one was injured.  Damage from the storm was minimal. During the warning period, members of the Big Island Amateur Radio Club stood by to help at Hawaii County Civil Defense, the Hilo Medical Center, and at various American Red Cross stations across the island. The Hilo International Airport reported winds between 30-35 knots early this afternoon (Monday) with rainfall gauges registering 2 to 4 inches (5.08 to 10.16 cm) of rain.  The situation could have been a lot worse, with early forecasts predicting up to 10 inches (25.4 cm) or more of rain by this evening. The remaining portions of "Flossie" will move past West Maui, Molokai, Honolulu (on Oahu), and Kauai later this evening.  Rainfall is expe

A 40-Meter Inverted L Antenna. Post #216

During the past few weeks, I've been experimenting with the versatile inverted L antenna for my small house lot.  I find the antenna simple, inexpensive, and easily concealed. An inverted L is a bent quarter-wave Marconi vertical fed against a system of surface, buried, or elevated radials.  The vertical segment should be as high as possible, with the remaining length running horizontal to a nearby tie off point.  Coaxial feed line can be used for monoband operation or 450-ohm ladder line can be employed if multiband use is planned. MATERIALS: Two vertical structures to support the antenna--one for the vertical segment and the other to tie off the horizontal wire running from the top of the mast.  I had a homemade 20-foot/6.09 meters pvc mast under the house and a convenient Norfolk Pine Tree at the edge of my property to support the horizontal portion of the antenna. Sixty-six feet/20.12 meters of #14 AWG house wire for the radial system and the antenna element. Three,

A Multiband "Lazy L" antenna. Post #215

One of my favorite antenna guides is a book by the late Doug DeMaw (W1FB) titled the "Novice Antenna Notebook."  Although it is a slim volume, it contains most of the facts, construction principles, and modifications needed to erect simple, inexpensive, and effective antennas. I bought the book 25 years ago while I was mentoring (elmering) a newly licensed ham in my neighborhood.  Since I'm not a technical genius, I decided to consult a basic antenna primer that could be used by the new licensee as well as myself.  I wasn't disappointed.  DeMaw's writing is down to earth, clear, and largely without complicated formulas for the beginning ham.  I still have this wonderfully simple volume squeezed in between other antenna tomes, including the ARRL Antenna Book, the ARRL Handbook, and various RSGB publications. What prompted me to consult DeMaw this late in my amateur radio "career" (I was licensed as a novice back in 1977), was the need to erect a simp

Ten Basic Antenna Truths. Post #214

Sometimes knowledge comes from the strangest places.  Take today, for instance. While my van was having a routine maintenance check at my local Honda dealer (I have an Odyssey van), I ran into an Dean Manley (KH6B), one of my oldest friends and former station engineer at Hilo radio station, KHLO-AM.  I worked at this station from 1976 to 2011.  We discussed a variety of antenna ideas, including improving the homebrewed antennas we use at our stations.  I consider Dean an expert in this area.  He has spent many years building and upgrading antenna systems for  AM and FM stations, both commercial and nonprofit. Anyway, we spent a good half-hour discussing some ideas, including his current project--a 40-meter vertical beam which Dean uses for the Hawaii Afternoon Net.  Before we parted, he gave me a copy of a handout he made for members of the Hilo Amateur Radio Club.  The one-sheet article, entitled "HF Antennas 101" by Van Field (W2OQI), appeared in the September 2004 iss

A 3/2 wavelength sloping dipole for 20 meters. Post #213.

One of the easiest and least expensive antennas for the amateur radio operator is the sloping dipole or "sloper."  Ed Noll (W3FQJ) defines the sloper as "a slanted half-wave antenna with one end of the antenna attached to (a) mast top and other end near to ground level."  According to Noll, the sloper shows "a modest directivity in the direction of its slope and considerably less signal pickup from its rear."  A well-designed half-wave sloping dipole can fit in a small city lot using a mast between 20 to 30 feet (6.09 to 9.23 meters), two dipole elements cut to your preferred frequency, a few insulators, a couple of tie-down stakes, and sufficient 50/72 ohm coaxial cable to reach your shack.  Multiband operation is possible using 450 ohm ladder line, a 4:1 balun, and an antenna transmatch. Since most of my ladder line was being used for other antenna projects, I decided to use 50 feet (15.24 meters) of RG-8X coaxial cable with UHF connectors for my feed