Showing posts from May, 2014

Simple Ham Radio Antennas: An Extended Double Zepp for 20 meters. Post #277

How would you like to have a simple dipole-like antenna that would give you almost 3dB over over the classical dipole antenna ?  You can if you're willing to build a Double Extended Zepp antenna for your favorite amateur radio band.   Now that I have enough room at my new home-in-progress in the Puna District of Hawaii Island, I decided to make a simple gain antenna for one of my favorite DX bands--20 meters. I had a spare MFJ telescoping fiberglass mast available, some leftover #14 AWG house wire in the garage, a spare 4:1 W9INN balun, a 50-ft./15.24 length of 450 ohm ladder line , a sturdy Drake MN-4 transmatch ("the tuner"), and 25-ft./7.62 meters of RG -8X coaxial cable with UHF connectors. I decided to configure the extended double zepp as an inverted V, knowing that its gain would be a bit less than a horizontal arrangement of a half wavelength dipole. With school over until mid-August, I thought this simple antenna project would give me something creat

Simple Ham Radio Antennas. A basic 40/15 meter dipole. Post #276

My antenna "farm" at the new QTH finally is taking shape. So far, I've built and used successfully a 40-10 meter inverted V fed with ladder line , a 5/8 wavelength vertical for 20, 15, and 10 meters, a 135-ft/41.15 meters "classic doublet" fed with ladder line that works from 80-10 meters, and a 40-10 meter delta loop fed with ladder line.  I've described these antennas in past posts.  All of them work very well with relatively low power (less than 50 watts) with my older rigs (Argosy II, Swan 100 MX, Yaesu FT-7, and a Kenwood TS-520). Although I prefer multiband HF antennas fed with 450-ohm ladder line, I still use a few single or two-band antennas fed with 50-ohm coaxial cable when I wish to experiment on 40 or 15 meters.  Last Sunday, 18 May 2014, I decided to build a simple two-band dipole covering the 40 and 15 meter bands using a single piece of RG -8X coaxial cable. The dipole would be designed for the lowest frequency range and then use the thir

Simple Ham Radio Antennas. A field-deployable 40-10 meter inverted V antenna. Post #275.

GOING TO THE FIELD FOR FUN AND SERIOUS BUSINESS Considering the amount of natural and human-made disasters making headlines this year, every amateur radio operator should have a "go-kit" should it be necessary to support your community in times of emergency.  Once you have this kit, practice using it so it becomes part of your support package. A "go-kit" should be portable, easy to set up, and contain the necessary equipment to get an amateur radio station on the air for emergency service.  Your emergency kit should also contain sufficient food, water, clothing, medical supplies, and personal items to last at least three days--more days if you can squeeze more stuff in your vehicle. So, with this in mind, I took inventory of the "back up station" I alway take with me in my Honda Odyssey van.  The station is simple and functional.  I schedule several portable operations each year to test out the equipment and my ability to operate in the field.  In

Simple Ham Radio Antennas. A 5/8 wavelength vertical antenna for 20 meters. Post #274

How would you like to have a simple, effective antenna for 20 meters thast will give you some gain over a ground plane antenna and exhibit a radiation angle of approximately 15 degrees? You can grab more DX (distance) at a modest cost by building a 5/8 wavelength vertical antenna working in conjunction with 1/4 wavelength radials beneath the main radiating element. I've built 5/8 wavelength antennas for 10 and 15 meters and they work very well.  If you desire multiband performance out of this antenna, you will need a balanced feed line (such as 450-ohm ladder line), a 4:1 current balun, and a sturdy ATU ( antenna tuning unit ).  If you prefer to use this antenna on one band only, you can establish resonance with a base loading coil that tunes the antenna to 3/4 wavelength  resonance.  Standard 1/4 wavelength wire radials are used with both versions of this antenna. According to William I. Orr (W6SAI) and Stuart D. Cowan (W2LX), "a 5/8 wavelength antenna provides imp

Simple Ham Radio Antennas: A 5/8 wavelength vertical for 15 meters. Post #273

Over the past few weeks, I've been experimenting with a 5/8 wavelength vertical antenna for 10 meters.  The antenna is a marked improvement over my 1/4 wavelength ground plane vertical for 28.400 MHz.  Some antenna experts believe the 5/8 wavelength vertical can deliver a 3 dB gain over the conventional vertical presented in most antenna books.  According to William I. Orr (W6SAI) and Stuart D. Cowan (W2LX), the "5/8-wave vertical provides improved performance DX-wise over the ground plane antenna and is recommended for those amateurs with restricted yard space who have 'nowwhere to go but up.'" With that in mind, I spent part of Saturday, 03 May 2014, building a 5/8 wavelength vertical for the 15 meter amateur radio band, with a preferred frequency of 21.260 MHz in the phone (SSB) portion of the band.  The antenna was simple, requiring some wire, a few wooden support stakes, some ceramic insulators, a "ladder lock" support for the feed line, a length