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Showing posts with the label Radio

Simple Ham Radio Antennas. Improvised Field Day Antennas. Post #283.

The 2014 ARRL Field Day is just about history as more than 35,000 amateur radio operators transmitting from 2,500 emergency sites finish the last action-packed hours in this annual communications exercise designed to test communications capabilities during man-made or natural disasters. I always enjoy Field Day activity, whether I spend a few hours operating, logging contacts, or even taking down the rapidly assembled antennas used for this part training exercise and part contest. Over the past few years, I've used some impressive rigs ( Elecraft K3) and neatly fashioned antennas, both commercial and homemade.   This year was no exception.  As usual, I put in a few hours working for my former radio station at a "Moku O Hawaii " outrigger canoe regatta on Hilo Bay before I slipped briefly over to the Field Day site of the Big Island Amateur Radio Club at the Wailoa Visitor Center in Hilo.  I'm on a retainer to work various remote broadcasts and a few sportin

Simple Ham Radio Antennas. On the ground antennas. Post #280

Over the past few weeks, I've become fascinated with antennas mounted on or near the ground. I've even built a few, such as Mike Toia's (K3MT) "grasswire" antenna and a similar "earth" antenna from Australia.  A few months ago, I built a simple beverage antenna for my old Hallicrafters SX-62A receiver.  All or these wire antennas worked very well, especially for the AM broadcast band . With a few modifications, these wires can be used as a separate receive antenna for amateur radio stations located in noisy or desert areas.  I've used vertical antennas for transmitting and low-mounted antennas for receiving.   So, what are these ground hugging "long wires?" According to articles published in the "NASWA Journal" for December 1992 and January 1993 by author Joseph Buch, these antennas mounted on, near, or slightly below ground level are called "wave" antennas because "they extract energy from the wave as it tr

Simple Ham Radio Antennas: The "Down To Earth Antenna." Post #279

Are you looking for an inconspicuous amateur radio antenna that is largely invisible, yet delivers acceptable DX and local results?  An antenna idea described by Robert McGregor (VK3XZ) and published in the May, 1993 edition of " Amateur Radio " (Australian magazine) may suggest a few alternatives for hams facing restrictive HOAs and CC&Rs. A few weeks ago, Dean Manley (KH6B), gave me a copy of this fascinating article for my antenna reference library.  I've built several disguised antennas, ranging from K3MT's "grasswire" antenna to low-lying dipoles running just above my home garden.  But none of this antennas worked as well as "The Down To Earth Antenna" from Robert McGregor (VK3XZ). Here are some pertinent paragraphs from Robert's article. DOWN TO EARTH ANTENNA Australia and the African Desert have a common need for radio communication and a mainly sandy terrain. VK5TL's letter, AR Jan. '92 caused me to dig deep into a

Simple Ham Radio Antennas: The Ghost of Antennas Past. Post #267

Humans tend to collect things.  Amateur radio operators are no exception.  In my 37 years as a licensed amateur radio operator, I've collected enough electronics-related material to fill most of my garage/radio shack at my new home in the Puna District .  Fortunately, I've managed to keep things organized, more or less, with plastic storage bins and some old filing cabinets. During the ongoing moving process, I discovered antennas, books, logs, and parts once given up for lost.  Such was the case Monday, 17 March 2014, when I reorganizing some of the material brought to the new QTH.  I found several well-sealed boxes containing some of my successful antenna projects.  All the antennas were dipoles built during my over three decades of "warming the ether" with a variety of old tube rigs long since gone to to the great capacitor in the sky.  After I finished using these antennas, I had the foresight to clean and store them for future use.  Also along the back wall wa

Simple Ham Radio Antennas: "The Poor Man's Beverage" Antenna. Post #265

Like many amateur radio operators, I've collected many boxes of electronic parts, various lengths of coaxial cable , and assorted rigs over the past 38 years.  I suppose my "shack" is testament to my "pack rat" tendencies.  I rationalize this collective habit by saying all of this material will become useful some day.  That some day was Thursday, 13 March 2014.  I had several lengths of RG-58 coaxial cable that had seen better days.  The assorted 100-ft/30.48 meters and 50-ft/15.24 meters lengths were gathering dust in the corner of the garage serving as the storeroom for my radio room.  The connectors were in good shape and the vinyl covering was intact, although a bit grey from sun exposure.  I wanted to find a use for the old cable ,now that it had been "retired" from active service. Why not use the old coax as a low noise receiving antenna for 80 meters, which was a very noisy band even in my remodeled home in the Puna District of Hawaii Islan

Simple Ham Radio Antennas: Sam's "James Bond" Antenna. Post #264

Whenever I get a day off from my substitute teaching duties, I try to attend meetings of the Hawaii QRP Club at the Hilo, Hawaii Jack In The Box Restaurant.  The meetings usually last from 0600 to 0900 local time and cover a variety of topics, from antennas to homebrewed equipment.  Attendance varies from to 2 to 7 or 8 persons, depending on who's working or free for the day.  Dean Manley (KH6B) usually brings some of his antenna notebooks and his vast storehouse of experience as a radio broadcast engineer to the meetings.  There's always something interesting or new at these gatherings. Recently, some of us have been discussing homebrewed antennas that can be operated from areas restricted by HOAs, CC&Rs , or just plain lack of space.  One of the most intriguing antenna ideas came from the late Sam Kumukahi (KH6AFS), who, during the 1990s, used what he called a "James Bond" antenna with excellent results for local and occasional DX contacts.  At the 27 Febr

Simple Ham Radio Antennas: The 10 meter 1/2 wavelength sloper. Post #262

The sloping 1/2 wavelength dipole is one of my favorite antennas.  "Slopers" are good antennas for restricted space areas.  They are simple to build, inexpensive, and exhibit some directivity in the your chosen direction. According to VK6YSF, VE2DPE, and other amateur radio operators, a properly designed 1/2 wavelength sloper radiates energy at low angles relative to the horizon with vertical polarization.  Slopers don't require a ground radial system and can be fed with a good grade of 50 ohm coaxial cable.  A sloper antenna only requires one tall support (tree, mast, edge of a roof, etc.) and occupies less space that a 1/2 wavelength horizontal dipole. So, let's build one of these simple, effective antennas for the 10 meter band , centering on 28.4 MHz --right in the middle of the techncian class phone band. MATERIALS: One tall support.  In my case, I used a 33-ft/10.06 meter MFJ telescoping fiberglass mast.. One 5-ft/1.52 meter wooden stake to support

Basic DX tips. Post #260

One of my favorite pursuits in amateur radio is chasing DX (distance) contacts with hams living or visiting in remote places of the world, be they small nations, islands, or even mountain tops.  Each contact is a small adventure to a place I may never see. For the dedicated contester or DX enthusiast, there are many attractive awards (i.e. DXCC , WAS, WAC, etc.) to pursue. I'm more of a "casual" DXer , squeezing in contacts when house building or part-time teaching permit.  For those moments when I'm free of family responsibilities, I enjoy listening and working exotic, far off places.  Since I live on Hawaii Island , I'm often the "target" of DXers...a task I thoroughly enjoy. During my 37 years as an amateur radio operator, I've experienced both the joy of making a rare contact and the frustration of losing some elusive call in a rush of QRM.  Such is the DX experience. There must be an easier way of making DX contacts than wading through a

Simple Ham Radio Antennas: Antennas without "tuners", part 1. Post #254

Antenna transmatches or "tuners" are wonderful devices that make amateur radio operations easier.  They can help minimize swr on antenna feed lines and extend the band coverage of your present antenna. However, there are times when such devices may not be needed, especially if you're designing an antenna for a single band or are contemplating an emergency or portable antenna for your "go" kit.  By carefully designing, cutting, and trimming your basic 1/2 wavelength dipole for the lowest swr, you can just connect a good quality 50 ohm coaxial cable feed line and run the band of your choice without much difficulty. In this post, I will describe a few simple coax-fed dipoles and inverted vees that will serve your favored amateur radio band without the need for an antenna transmatch .  Of course, you could always insert a transmatch into the system to squeeze out the maximum power at the lowest possible swr if you so desire.  These antennas work either way.