Thursday, February 27, 2014

Simple Ham Radio Antennas: An 80-10 meter inverted vee dipole. Post #263

A few days ago I read a fascinating antenna article by Cecil Moore (W5DXP) on the http://www.eham.net website.  Cecil described what he called a "Multi-Band 33-ft dipole" that works on 20, 17, 15, and 10 meters without an antenna "tuner" (i.e. transmatch).  The secret to this outstanding antenna was the use of 450 ohm ladder line in conjunction with a series of switches and relays that selected the proper length of ladder line used to feed the antenna.  Depending on the band of use, Cecil could insert and remove sections of ladder line with his relay/switch system so that swr across his chosen band remained low.  By carefully selecting which section of feed line to add or subtract, he got a decent performing antenna without having to resort to a transmatch or "tuner."

Cecil's idea got me thinking of ways to improve the dipoles I'm using at my new home site.  Although his idea has a lot of merit, I felt the need to build something a bit simpler that would get similar results.  My requirements were simple:

The antenna would require one tall support.  I didn't want to climb trees to erect an antenna.  At my age, a fall really can ruin your day.

The antenna had to cover Hawaii Afternoon Net frequencies, 3.888 MHz and 7.088 MHz.  I would also like to work some DX on 20 through 10 meters.  So, the antenna would have to cover 80 through 10 meters.

Although I had erected a basic doublet in December 2013, it had fallen victim to a winter storm and high winds.  I needed a replacement for this general coverage antenna.

The 40-meter loop had been removed to make way for a family garden in the back yard.  My xyl and I are trying to become more food self-sufficient.

So, I decided to re-invent my first novice class antenna--the 80 to 10 meter inverted vee.  As I remember, the antenna was cheap, only took one tall support, and could cover several amateur radio bands with the use of an antenna transmatch, a 4:1 current balun, some surplus speaker wire, and a length of 450 ohm ladder line.  Most of the materials were stored in the new garage along with ceramic insulators, a "ladder lock" center connector, some wooden support stakes, various lengths of RG-8X coax with UHF connectors, and some spare tools.

The construction would be straight forward, with most of the building done on the ground and the antenna later raised into position on a fiberglass mast.  The inverted vee is a simple antenna, which is nothing more than a drooping 1/2 wave dipole cut for your lowest operating frequency and fed with ladder or open wire line to a balanced "tuner" capable of accepting such a line.  In the absence of a balanced "tuner", you can connect the ladder line to a 4:1 current balun and use a short length of 50 ohm coaxial cable to connect the antenna system to your transmatch or "tuner."

CONSTRUCTION PHASE:

Using the general dipole formula 468/f (MHz)=L (ft) and the lowest design frequency of 3.500 MHz, I came up with a total dipole length of 137.71 ft/40.76 meters.  Each sloping dipole element would measure 68.85 ft (around 68 ft, 10 in.)/20.38 meters.  The only wire available last weekend for the project was about 150 ft/45.73 meters of #18 AWG speaker wire from Radio Shack.  For most of my antennas, I try to use stronger wire, such as #14 AWG household wire.  But in this case, the speaker wire was all I had.

I attached a ceramic insulator to one end of each antenna element.

I had a spare 33 ft/10.06 meters  MFJ telescoping fiberglass mast in the garage that would serve as the support for the inverted vee.  I extended the mast to its full length and proceeded to attach the 450 ohm ladder line to the mast.  I would be using 90 ft/27.43 meters of ladder line, because the antenna would be erected at one end of the garden which was approximately 65 ft/19.81 meters from the radio room in the garage.  I attached a "ladder lock" device to one end of the ladder line, looped a piece of nylon rope through the top support hole, and tied the "ladder lock" to the tip of the mast.

I ran the ladder line down from the top of the 33 ft/10.06 meter mast to a point about 8 ft/2.43 meters above the bottom of the mast.  The ladder line was secured to the mast by nylon ties.

Each antenna element was soldered to a leg of the ladder line.  Connections were wrapped with several layers of vinyl electrical tape.

With construction complete, I drove a 5 ft/1.52 meter wooden support stake into the ground to support the fiberglass mast.

I then hoisted the mast into position, tied off each antenna element to nearby trees with nylon rope, and adjusted the antenna to a uniform shape.  The ends of each element were approximately 10 ft/3.04 meters above ground level.

I then pounded six, five-ft/1.52 wooden stakes into the ground, each 10 ft/3.04 meters apart, to support the ladder line off the ground until the ladder line reached the window of the shack, some 65 ft/19.81 meters from the base of the mast.

I slipped the ladder line through the bottom of the shack window and connected it to a W9INN 4:1 current balun.  A three-ft/0.91 meters length of RG-8X coax with UHF connectors mated the antenna with the Drake MN-4 transmatch ("tuner").  Short pieces of RG-8X connected the Ten-Tec Argosy II with the Drake MN-4, a low pass filter, and a Heathkit Dummy Load.  If I want to use 30 meters, I substitute a MFJ-941E Versa Tuner II for the Drake MN-4.  The Drake "tuner" doesn't cover 30 meters.  As a final step, I attached a 68-ft/20.73 meters "counterpoise" to the ground lug of the antenna transmatch.  The "counterpoise" is in addition to the regular station ground which uses a short length of copper braid clipped  to an 8-ft/2.43 meters copper ground rod.

INITIAL RESULTS:

With the Drake MN-4 or MFJ-941E in the line, I can get a swr of 1.1 to 1 on all bands from 80 to 10 meters.  Unlike other multi-band designs, this antenna requires an antenna transmatch or "tuner" to work properly.  Because of its relatively low height, the inverted vee works very well as a NVIS (near vertical incident skywave) antenna on 80 and 40 meters.  This antenna provides excellent local and state wide coverage throughout the Hawaiian Islands.  DX begins to pick up at 20 meters, where the apex of the antenna is nearly 1/2 wavelength above ground.  When 15 and 10 meters are open, I get good signal reports on both cw and ssb.

The inverted vee gives me satisfactory performance at a cheap price.  It's easy to build, requires no ground radial system, and can be used in portable or emergency situations.  Most of the materials for this simple, effective antenna can be found at the nearest hardware store or home improvement outlet.  Some of the accessories, such as insulators and center supports can be "homebrewed" with plastic, teflon, or even plexiglass.

REFERENCES:

http://www.hamuniverse.com/hfdoublet.html.

http://www.w4rnl.net.46/abd.html.

http://www.designerweb.net/downloads/DoubletAntenna_80-10m.pdf.

http://www.theladderline.com/doublets-ladder-line-and-automatic-remote-tuners.

http://www.eham.net/articles/31603.  This is the outstanding antenna article by Cecil Moore (W5DXP).

You can follow our blog community with a free email subscription or by tapping into the blog RSS feed.

Aloha es 73 de Russ (KH6JRM)

BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.


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Sunday, February 23, 2014

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 the fiberglass mast.

One 6-ft/1.82 meter wood stake to tie off the sloper.

Two ceramic insulators, one for the upper portion of the sloper and the other for the bottom portion of the sloper.

One coaxial cable center connector.  I had a spare Budwig HQ-1 center connector in the junk box.  You could also make a center connector from wood, plastic,or another ceramic insulator.

Fifty feet/15.24 meters of RG-8X coaxial cable with UHF connectors.

Basic tools, including a soldering gun/iron, pliers, wire cutters, vinyl electrical tape.

A length of #14 AWG house wire for the two antenna elements.  Using the general dipole formula of 468/f (MHz)=L(ft) and a working frequency of 28.4 MHz, I cut a piece of wire measuring 16.47 ft/5.02 meters.
This length was cut in half to get each dipole segment.  Each segment then measured 8.23 ft/2.51 meters.

Several 3-ft/0.91 pieces of RG-8X coaxial cable to interconnect shack equipment (rig, low pass filter, dummy load) to the Drake MN-4 antenna transmatch.

Fifty-feet/15.24 meters of dacron rope to tie off the sloper to a nearby wooden stake.  I wouldn't need all of the rope for this antenna, but I decided to use what I needed and coiled up the rest  for use in future sloper antenna projects.



ASSEMBLY:

The antenna was made in the garage and then taken outside to be strung from the fiberglass mast.  Prior to making the antenna, the fiberglass mast was positioned on the ground.

I attached a ceramic insulator to each segment.  The insulator on the lower element would be attached to the wooden support stake by dacron rope.  As mentioned above, the rope length would be kept intact for other sloper projects.

I attached the upper segment of the sloper element to the + side of the Budwig center connector and attached the lower segment to the - side of the Budwig center connector.  All connections were soldered and wrapped with several layers of vinyl electrical tape.

Before I attached the RG-8X coaxial cable, I wound a "choke balun" consisting of 6 turns of the cable measuring approximately 8 inches/20.32 cm in diameter.  The balun was secured by vinyl electrical tape.  I then attached the RG-8X coaxial cable to the center coax connector.  After that, I attached the upper end of the top segment to a ceramic insulator.

Once outside, I attached the upper ceramic insulator to the top of the mast with short pieces of dacron rope.
I then tied some dacron rope to the ceramic insulator at the bottom of the lower antenna segment.

I slowly raised the mast and slipped it over the wooden support stake.

The lower end of the sloper was tied to a 5-ft/1.52 meter wooden stake approximately 30 ft/9.14 meters from the base of the mast.  The RG-8X feed line was run from the sloper at a right angle and secured to the base of the fiberglass mast with nylon ties.

I ran the RG-8X coaxial cable through the shack window and into the Drake MN-4 antenna transmatch. The Ten-Tec Argosy II transceiver, a low pass filter, and the old Heathkit Dummy Load were connected to the transmatch by short pieces of RG-8X patch cable.

INITIAL RESULTS:

Without the Drake MN-4 in the system, the swr measured 1.6 to 1 between 28.3 MHz and 28.5 MHz. With the transmatch in the system, I was able to get a swr of 1.1 to 1 on those frequencies. I was also able to use the lower portion of the band for cw if I adjusted the Drake MN-4 to compensate for the small mismatch between the transceiver and the antenna.

Although 10 meters is a bit uncertain at times, I was able to get some excellent contacts in California, Oregon, and Washington State on 28.4 MHz between 1100 to 1600 local time (2100 to 0200 UTC).  My ssb reports ranged from 53 to 57.  Not terribly outstanding, but usable.  I didn't note much directivity in the antenna when I shifted position of the sloper by moving the wooden support stake.  I may have gained a single "s" unit when I pointed the sloper toward the U.S. mainland.

This was a fun project.

REFERENCES:

http://www.dxzone.com/catalog/Antennas/sloper/.

http://www.dxzone/cgi-bin/dir/jump2.cgi?ID=27575.

ARRL Antenna Book, 18th Edition.

http://hamradiosecrets.com/ham-radio-hf-antenna.html..

Thanks for joining us today!.  You can follow our blog community with a free email subscription or by tapping into the blog RSS feed.

Aloha de Russ (KH6JRM).
BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.
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Monday, February 17, 2014

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 current balun and an antenna transmatch to work properly.

Several months ago, I built a replica of Siegel's design at my new homestead in the Puna District of Hawaii Island.  I configured the antenna as an inverted "L", using a 33-foot/10.06 meters MFJ telescoping fiberglass mast as the main support.  One wire ran up the mast, with the remaining 51 feet/15.54 meters of wire run horizontally to a nearby Norfolk Pine Tree.  A W9INN 4:1 balun was secured inside a waterproof plastic storage container at the base of the mast, with 17 feet/5.18 meters of AWG #14 house wire  attached to one terminal of the balun and 84 feet/25.60 meters of AWG #14 house wire attached to the other balun terminal and run up the mast and then onto the tree.  The "counterpoise" wire was elevated 3 feet/0.91 meters off the ground to a nearby wooden stake.  Twenty- five 7.62 meters of RG-8X coax was attached to the balun, run into the shack, and attached to my trusty Drake MN-4 transmatch. 

That arrangement worked well and was largely invisible to the neighbors.  I later took down the antenna and stored it in the garage.

Not much else was done in this area until I discussed the W3EDP antenna with Dean Manley (KH6B) at one of our impromptu meetings at the Hilo Jack In The Box Restaurants on Thursday, 13 February 2014.  He gave me some reference material on Siegel's antenna, which I found most valuable, since I was considering re-erecting another W3EDP antenna on my property.

This time around, I decided to incorporate 17 feet/5.18 meters of 450 ohm ladder line as part of the system.  This vertical variant of the W3EDP antenna was used successfully by AE5VV , NC4FB, and other hams.  The antenna would have a vertical section of 450 ohm ladder line, with one leg of the ladder line attached to 67- feet/20.42 meters  of AWG #14 house wire run up a fiberglass mast and then onto a nearby tree--the very same support system used in my first W3EDP antenna.  The left leg of the ladder line would be left as is and would serve as a matching section for the antenna.

The 4:1 balun would be in the same plastic storage box as before, but with a "counterpoise" bundle consisting of a 17-ft/5.18 meters length of #14 gauge wire and the another #14 gauge wire measuring 33- feet/10.06 meters.  The longer wire would be used for 80 and 40 meters, while the shorter wire would be used for 20 through 10 meters.  Some amateurs who have built this antenna say the shorter wire isn't necessary for 10 meters.  I just left the wire in the system.  The "counterpoise" system would be connected by small battery clips, depending on the bands chosen.  I also attached the same "counterpoise" bundle to the ground lug of my Drake MN-4 antenna transmatch.

Finally, 25-feet/7.62 meters of RG-8X coaxial cable would be attached to the balun and run into the shack's Drake MN-4 antenna transmatch.

MATERIALS:

Most of the materials left over from the previous W3EDP antenna were reused.

I secured 17-feet/5.18 meters of 450 ohm ladder line to the fiberglass mast.  The "counterpoise" bundle was attached and soldered to one leg of the ladder line, while 67-feet/20.47 meters of antenna wire (#14 gauge house wire) was attached and soldered to the remaining leg of the ladder line.  All connections were covered by several layers of vinyl electrical tape.  The vertical wire was secured to the mast by nylon ties, with the remaining length (51-feet/15.54 meters) of wire  shot over a branch in a nearby Norfolk Pine Tree with a slingshot.  The branch was about 30-feet/9.14 meters above ground.  The end of the antenna wire was attached to a ceramic insulator and tied off with some fishing line I had in the garage.  The total length of the vertical element measured 84-feet/25.60 meters.

I hoisted the mast onto its wooden support stake and attached the "counterpoise" bundle to a nearby wooden stake.  The stake kept the wires approximately 3-feet/0.91 meters off the ground.  I then attached 25-feet/7.62 meters of RG-8X coaxial cable to the balun, ran the cable through the shack's patch panel, and attached the cable end to the Drake MN-4 antenna transmatch.  Small pieces of coax interconnected the antenna "tuner" to the Ten Tec Argosy II, a low pass filter, and the Heathkit Dummy Load.

INITIAL RESULTS:

Not bad for a quickly built antenna.  With the help of the Drake MN-4, I can get SWR readings of 1.3 to 1 across my bands of interest.  Even with the Argosy II running 5 watts, I get plenty of contacts  in Hawaii, throughout the Pacific, and on the U.S. mainland.  Most of my cw signal reports are between 559 and 579 with ssb contacts ranging from 54 to 58, depending on the band in use.  I had a lot of fun building this "classic" antenna.  It works.  It's cheap. And it's lightweight.

REFERENCES:

Manley, Dean W. (KH6B).  "If it's not 84 feet, it's not W3EDP."  Contained in "On Frequency", Volume 41, No. 6.  June 1998.

Beers, Yardley (W3AWH/W0JF).  "An Unorthodox Antenna."  "QST", March 1936. pp. 32-33.

W3EDP Antenna.  "World Radio".  November 1997.  p. 59

The ageless W3EDP antenna.  "Technical Topics."  April 1985.

http://www.ok1rr.com/index.php/antennas/19-the-w3edp-antenna.

http://www.nc4fb.org/wordpress/w3edp-multi-band-antenna.

http://www.zerobeat.net/g3ycc/w3edp.htm.

Thanks for joining us today!  You can follow our blog community with a free email subscription or by tapping into the blog RSS feed.

Aloha de Russ (KH6JRM)

BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.
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Monday, February 10, 2014

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 sea of calls and "big gun" stations.  Plenty of low power guys like myself with homemade antennas and simple transceivers have made DXCC, while I still struggle at times to "break through the wall" of competing signals.

Early this morning (Monday) before I headed off to my substitute teaching position, I  read a fascinating, enthusiastic article on e.ham.net that may help me and other "little pistols" do better in the DX department.

E.ham.net republished an article by Brennen Ernst (KI4PRK) called "DX for beginners by a beginner." When the original article was published in 2007, Brennen was a 13-year-old student, who had a remarkable knack for snagging contacts in far away places.  His simple approach answered a number of vexing questions that had always bothered me.  Perhaps my equipment or antennas weren't the source of my lackluster DX performance.  Most likely, my approach to DXing and contesting was the result of certain human or behavioral factors that had gone unnoticed for years.

What Brennen offered was a simple way to approach DXing and contest operations that reduced frustration and increased contacts.  Some of his suggestions I already knew, but failed to implement fully.  And yes, a certain touch of arrogance played a role, too. Afterall, I was an Extra Class ham with over 37 years of experience.  One thing I've learned by a return to teaching is that students can often "teach" their instructors.  A fresh set of eyes and ears often can do wonders to a mind befogged with old ideas and practices.

So, I read Brennen's essay and incorporated his methods into the few hours of operating I had before reporting to my substitute teaching job.  In an hour of casual operating, I was able to contact a few more stations than I normally do.  I was elated because my modest station (Swan 100- MX transceiver and an inverted vee and delta loop) seemed to do much better than before.  Perhaps, I was the biggest stumbling block to success.

Here are some of the recommendations from Brennen Ernst (KI4PRK) that can help boost your contest and DX skills:

Listen before you transmit.

Be courteous.  Treat others as you would like to be treated.

Follow the instructions of the DX or contest station.

There is always propagation somewhere, someplace.  If one band is "closed", try another.

Study propagation, so you can operate when band conditions are good.  The internet contains many propagation programs that can help you anticipate conditions.  You can also monitor propagation bulletins from the ARRL.

Be patient.  This is the greatest skill I had to learn.  Do something else until the "big guns" leave the frequency.

A "plain" 100 watt transceiver and a carefully designed dipole or vertical can produce excellent contacts.  This was one of the reasons I decided to build my own antennas.  I wanted to experience success with something I built with my own two hands.  Again, patience is the key.

Study books and articles about propagation, contest operations, and DXing.  One of the best books on the subject is "The Complete DXer" by Bob Lochner (W9KNI).

Upgrade your license to Extra Class.  The bottom 25 kHz of each Amateur Band is a treasure trove of exciting and often rare contacts.  One of the reasons I finally took and passed the Extra Class License Exam was to gain access to these frequencies.

Learn CW and use various digital modes.  Much of the "exotic" DX uses CW and other digital modes, such as PSK31, Olivia, JT65, and even RTTY.  There are many software programs  to help interface your rig with your computer.

I found the recommendations from this young ham were most valuable in managing my on-air time and getting more DX contacts.  Don't be afraid to learn something new or to experiment with different antennas, modes, QRP, or transceivers.  Amateur Radio is not a static activity.  It's a continuous learning experience that will keep us alert and active until that final switch is pulled and our bodies resume room temperature.

RESOURCES:

http://www.hamuniverse.com/newtohfbands.html.
http://www.hamuniverse.com/techniciantopics.html.
http://www.wa9wsj.com/operating_page.html.
http:www.contesting.com/
http://www.eham.net/articles/31620

Thanks for joining us today.  You can follow our blog community with a free email subscription or by tapping into the blog RSS feed.

Aloha es 73 de Russ (KH6JRM)
BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.

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Saturday, February 8, 2014

Simple Ham Radio Antennas: A Low HF Band Triangle. Post #259

Over the past few years, I've built a variety of HF antennas for my amateur radio station.  All of my verticals, inverted vees, dipoles, and loops have been a learning experience, especially when I've been faced with limited resources and space.  Operating from an apartment or a home governed by CC&Rs and HOAs has been a challenge.

Now that I'm slowly moving into a full acre of space in the rural Puna District of Hawaii Island, my space restrictions are gone and there are no committees to oversee my antenna activities.  I count this as a definite blessing.  For the first time in many years, I can build full sized dipoles, verticals with a decent ground system, and large full-wave loop antennas without interference.  Since my new property is surrounded by tall trees approaching 50 feet/15.24 meters, my antennas are well shielded from prying eyes.  When I operate out of my rental home in Laupahoehoe, I'm still hemmed in by utility poles and neighbors.  My antenna efforts at that place are generally stealthy and largely out of sight.

Last Saturday (01 February 2014), I decided to erect another loop antenna in the backyard facing Highway 130, the road running from Hilo to Pahoa.  I prefer full-wavelength loops because they are easy to make, don't require a ground radial system, exhibit some gain over a dipole, and can be fed with either coaxial cable through a quarter-wavelength matching section or 450 ohm ladder line.  The coaxial cable-fed system works best on one band, although other frequencies can be used if an antenna transmatch is inserted into the system.  Multi band coverage is possible with ladder line, a 4:1 balun, and an antenna transmatch.

For this antenna, I decided to use 450 ohm ladder line in conjunction with a 4:1 balun and an antenna transmatch.  The antenna would be used on all amateur radio frequencies between 40 and 10 meters.

I patterned the loop antenna after a design described by Edward M. Noll (W3FQJ) in his book "73 Vertical, Beam, and Triangle Antennas."  Noll called his loop "A Low Band Triangle Antenna."

MATERIALS:

The first item in the construction process was to determine the length of wire required, the type of support needed, and the lengths of 50 ohm coaxial cable and 450 ohm ladder necessary to connect the "Triangle Antenna" to my shack equipment.

Rather than use the standard formula of 1005/f(MHz)=L(ft), I used Noll's recommended formula of 984/f(MHz)=L(ft).  When I used the first formula, my antennas proved to be a bit long and I had to trim excess wire to bring the antenna to resonance and low swr.

Using the latter formula and a design frequency of 7.088 MHz (the frequency of the daily Hawaii Afternoon Net), the total length of wire needed worked out to be 138.82 ft (138 feet, 9.8 inches/42.32 meters.)  The only wire I had in the shack was 150 ft/45.73 meters of Radio Shack AWG #18 gauge speaker wire.  If I split the wire apart, I would have more than enough wire for the triangle antenna.

Three ceramic insulators, one for the apex of the triange at the top of the mast and two for supporting the bottom portion of the antenna.

Six, 6-ft/1.82 meters wooden stakes, one to support the mast, two to support the bottom ends of the triangle antenna, and three to support the ladder line off the ground as it ran to the 4:1 balun and the shack.

One 33-ft/10.06 meters MFJ telescoping fiberglass mast.

One W9INN 4:1 balun.

Fifty-feet/15.24 meters of 450 ohm ladder line and a "ladder lock" device to attach the ladder line to the bottom section of the triangle antenna.

Twenty-five feet/7.62 meters of RG-8X coaxial cable with UHF connectors.

Several 3-ft/0.91 meters lengths of RG-8X coaxial cable to interconnect the transceiver (Ten Tec Argonaut II) with the MFJ-941-E Versa Tuner II, the Heathkit Dummy Load, and a low pass filter.

Various tools, including a soldering gun, tape, wire cutters, dacron rope, pliers, and screwdrivers.

ASSEMBLY:

The triangle antenna was built on the ground.

I arranged the antenna in a general equilateral configuration measuring 46.27 feet (46 feet, 3.24 inches)/14.106 meters on a side.  I threaded the speaker wire through each ceramic insulator, leaving a space open midway through the bottom portion of the triangle antenna.

I attached the 450 ohm ladder line to the "ladder lock" center connector and soldered the free ends of the antenna to their respective leads on the ladder line.  The connections were covered by serveral layers of vinyl electrical tape.

At the connection point, I hammered in a 6-ft/1.82 meter wooden stake to support the antenna/feed line connection.  I also drove in a support stake for the fiberglass mast and the two support stakes which tied off the bottom portion of the triangle antenna.  Small lengths of dacron rope were used to secure the ceramic insulators to the support stakes.

Two remaining wooden stakes were driven into the ground approximately 15-ft/4.57 meters apart.  These stakes would support the ladder line off the ground until it reached the 4:1 balun attached to the garage wall.


I attached the apex of the triangle antenna to the tip of the 33-ft/10.06 meter fiberglass mast and slowly hoisted the mast onto its support stake.

I adjusted the antenna to a uniform, balanced shape and led the ladder line to its remaining support stakes.
I ran the ladder line to the first and second support

At the final support stake, the ladder line was run to the 4:1 balun attached to the garage wall (approximately 8-ft/2.43 meters above ground).

I attached 25-ft/7.62 meters of RG-8X coaxial cable to the 4:1 balun and ran the coax through a patch panel into the shack.  The coax was attached to the MFJ-941 Versa II antenna transmatch.  Small lengths of RG-8X coaxial cable were used to interconnect the rest of the shack equipment--the Ten Tec Argosy II, the low pass filter, and the Heathkit Dummy Load.  I have several other rigs in the shack, but the Ten Tec Argosy II was the only rig capable of using 30 meters.  Same goes for the trusty Drake MN-4 antenna transmatch.

PRELIMINARY RESULTS:

With the Versa Tuner II in the line, I was able to cover 40, 30, 20, 15, and 10 meters with swr readings below 1.5 to 1.  Using 10 to 20 watts from the old Ten Tec Argosy II, I was able to make excellent contacts throughout the state of Hawaii, on the U.S. mainland, and throughout the South Pacific.  CW reports ranged from 559 to 599 and SSB varied between 54 and 59.  For now, this "Low Band Triangle Antenna" works well and has provided hours of enjoyable contacts.  Try a loop antenna.  It's cheap, easy to build, and provides both local and DX coverage.  Have fun!

REFERENCES:

Noll, Edward M. (W3FQJ).  73 Vertical, Beam, and Triangle Antennas.  Editors and Engineers.  Indianapolis, IN, 46268.  Seventh Printing, 1979. pp. 126-127.

http:/www.w5sde.net/delta_loop_for_hf.htm.

http://www.hamuniverse.com/kl7jrloopnotes.html.

Thanks for joining us today!  You can follow our blog community with a free email subscription or by tapping into the blog's RSS feed.

Aloha es 73 de Russ (KH6JRM).

BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.


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Sunday, February 2, 2014

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 announcer for my former radio station employer and my work as a substitute teacher, I can usually operate when everyone else is either at work or asleep.

But with new spaces available for antennas, I'm building better antennas to fit my operating preferences.

So, with that in mind, I've begun a serious program of antenna design and building--something once denied to me by severe space restrictions.

To date, I've  posted a few articles detailing my attempts to build antennas that don't require "tuners" or transmatches.  I have two excellent "tuners" at my disposal--an old Drake MN-4 and a current model from MFJ, the 941-E versa tuner II.  The MFJ is used for my 80-10 meter ladder line-fed doublet, while the trusty Drake is used to "smooth out" the small mismatches on my 40-10 meter inverted vee and the recently built "Fan Dipole".  The 40, 20, and 10 meter "Fan Dipole" can be used without a "tuner", since the swr for each dipole is less than 2 to 1 across each band.

On Saturday, I decided to build another "tunerless" antenna.  This time around, I consulted the late William I. Orr (W6SAI).  In his "HF Antenna Handbook", he describes a fascinating loop antenna designed by his close friend Bob (AG9C).  I built a copy of this intriguing antenna this past Saturday at the new place.  I found it to be a "very forgiving" design for my location.

MATERIALS:

I configured the AG9C as a vertical loop antenna with the horizontal portion of the loop running between two self-supporting telescoping fiberglass masts.

Two tall supports.  I used two 33-ft/10.06 meters MFJ telescoping fiberglass masts.

Two ceramic insulators to shape the horizontal delta loop.

One hundred thirty nine feet/42.37 meters of #14 AWG house wire for the loop.

Two five-foot/1.52 meters wooden stakes to support each mast.

One 4:1 current balun.  The bottom of the loop will be connected to each terminal of the balun.  I had a spare W9INN balun in the shack.

One plastic storage bin to support the balun and to enclose the balun when operating is done.

Fifty feet/15.24 meters of RG-8X coaxial cable with UHF connectors.

Two small battery clips.

Six feet/1.82 metes of RG-8X to run from the window patch panel to the station equipment.

Several 3-ft/0.91 meters lengths of RG-8X coax to interconnect station equipment.

ASSEMBLY:

I built the loop antenna on the ground.

I laid out a roughly equilateral triangle on the ground.

I fastened a ceramic insulator to the top of each mast.

The antenna was threaded through each insulator.

I slowly hoisted the horizontal loop into position, with the horizontal part of the delta loop measuring 46.33 feet/14.12 meters.

The remaining parts of the horizontal delta loop were brought down to the 4:1 balun sitting on the raised plastic storage box.  These sections were attached to the terminals of the balun with two small battery clips.

The RG-8X coaxial cable feed line was attached to the balun and run through the patch panel in the shack window.  A 6-foot/1.82 meters piece of RG-8X was run from the patch panel to the Drake MN-4 transmatch.  The transmatch was bypassed except for the SWR meter and power level indicator.

Several short pieces of RG-8X coax were used to interconnect the transmatch, low pass filter, and dummy load to the Swan 100 MX transceiver.

INITIAL RESULTS:

I was quite surprised how well the vertical  loop worked without the Drake MN-4 or MFJ 941-E versa tuner.  The swr was less than 2 to 1 across the 40, 20 and 15 meter bands.  With the MFJ 941-E versa tuner in line, I was able to use the horizontal loop on 80, 30, and 10 meters.  It should be noted that I found, like AG9C, the input impedance of the loop on 80 meters was high, as it is a half-wave resonance.  None the less, a transmatch easily matches the feed line to the transmitter.  As AG9C states, "antenna radiated power is reduced, but adequate, over the CW portion of the 80- meter band."  I won't be using the antenna on 80 meters, anyway.  I'll  defer to my ladder line- fed 80 to 10 meter doublet for 80/75 meter operation.

I kept the Swan MX 100 below 50 watts and had some excellent contacts with the South Pacific and the mainland United States.  This was a fun antenna to build.  I had all of the materials on hand, so a trip to Radio Shack or to Hilo Ace Hardware wasn't necessary.  Best of all, I didn't have to install a ground radial system.

REFERENCES:

Orr, William I. (W6SAI). The W6SAI HF Antenna Handbook.  CQ Communications, Inc.  Hicksville, NY, 11801.  Fourth Printing, 2005. pp. 5-4 to 5-5.  This book is full of interesting antennas that can be built at low cost in space restricted areas.

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Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM)

BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.



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