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Showing posts with the label Russ Roberts

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: 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 W3EDP antenna revisited. Post #261

The "classic" W3EDP antenna has been around since March 1936 when Yardley Beers (W3AWH/W0JF) described a multiband antenna built by his friend H.G. Siegel (W3EDP).  Siegel used the traditional method of "cut and try" to arrive at an antenna length that would work satisfactorily on 160, 80, 40, 20, and 10 meters. Beers remembered that "A length of 84 feet (25.60 meters) seemed to stand out as being the best of all the combinations tried."  A similar "test and tune" method was used to determine a satisfactory counterpoise length of 17 feet (5.18 meters), "as the one working best in combination with the antenna." Since that time, several variations of this true "Zepp" antenna have been developed to facilitate portable, emergency, and even home use.  Many QRP enthusiasts use some kind of W3EDP-derived antenna for their operations.  The W3EDP antenna is a simple, cheap, and field deployable.  The antenna requires a 1:1 or 4:1

Simple Ham Antennas: The AG9C Loop Antenna. Post #258

Over the past 37 years as a licensed amateur operator, I've accumulated a wide variety of antenna reference material, including books, magazine articles, and topics discussed on amateur radio forums.  All ARRL members can further augment their antenna research by accessing the digital files of " QST ", the offical journal of the ARRL.  All told, there is an almost endless resource of antenna building ideas for most every ham station. Recently, I began to put some of these "classic ideas" to use on my new property in the Puna District of Hawaii Island .  I now have an acre of space to "plant" my antenna "farm"--quite a change from my present rental home which is hemmed in by neighbors and utility poles.  Although my neighbors have been tolerant of my amateur radio pursuits, I try to keep a low profile.  Namely, my verticals and inverted vees are usually lowered when they are not in use and, because of my part-time employment as a sports an

Simple Ham Radio Antennas: Antennas without tuners, part 4. Post #257

So far, the "tunerless" antennas I've built have worked very well.  They have been made with locally available materials from my "junk" box, neighborhood garage sales, and the nearby Ace Hardware Store.  These antennas have consisted of individual dipoles/inverted vees for my bands of preference (40, 20, 15, 10 meters), telescoping fiberglass masts (33-ft/10.06 meters tall), a single RG -8X coaxial feed line , and supporting wooden stakes or tree branches. Dipoles for each band were built on the ground and were later hoisted into position via a halyard and pulley system.  A "choke balun" made from part of the RG-8X feed line was attached to the mast just below the center connector at the top of the mast. In my first multiband antenna system, I changed bands by lowering and raising the appropriate antenna into place.  I couldn't change bands by staying in the shack. My second system was a modified "fan dipole/inverted vee" using mul

Simple Ham Radio Antennas: Antennas without "tuners", part 3. Post #256

In some of my previous posts, I've investigated, built, and used multiband dipole and inverted vees using a single 50 ohm coaxial feed line .  With a telescoping fiberglass mast (33-ft/10.06 meters extended), a simple halyard and pulley system, and separate antennas cut for each band of use (40, 20, 15, and 10 meters), I've been able to change bands fairly quickly by lowering the dipole/inverted vee elements, substituting those of another band, and raising the new antenna.  With each band element cut for the desired frequency, the efficiency is high with low swr for that band.  Since each antenna element is trimmed for the lowest swr at my mast location, an antenna transmatch isn't necessary.  Sometimes, as in the case with the 40 meter dipole/inverted vee, an antenna cut for the cw portion of the 7 MHz band will often work well on the phone portion of 15 meters (21 MHz band). The 15 meter band will operate on the third harmonic of the 40 meter band . In order to save

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.