Sunday, December 29, 2013

Simple Ham Radio Antennas--Antenna Resolutions for the New Year. Post #251

The Year 2013 has been an exciting and challenging year for amateur radio operators worldwide.  From earthquakes to tornadoes and from typhoons to floods, the amateur radio community has rendered valuable aid to those in distress.  A special thank you to the "hams" in India and the Philippines who struggled to maintain communications with officials and aid agencies, often without rest and relief.  You have served in the highest tradition of the amateur service.  I also commend my fellow amateurs who kept emergency frequencies free for health and welfare traffic.  I am proud of all of you.  Yes, this past year has been far from dull.

With this in mind, I decided to review my own year in amateur radio to see where I could improve my commitment to my community, maintain a safe, efficient station, and pursue my antenna interests with a minimum of cost.  So, I started making a list of things accomplished and areas where I could do better.

Perhaps my introspective analysis will encourage you to do the same.

First, I thank all those who have responded to my antenna projects.  Your encouragement, corrections, and guidance have proven invaluable in expanding my understanding of "homebrewed" antennas.  Like many of you, my imagination is limitless, but my finances are finite.  Being retired has been a mixed blessing.  I enjoy life a lot more than in my "working" past, especially when my xyl and I continue to find enrichment in our substitute teaching positions at the Laupahoehoe Community Public Charter School.  For the first time in our lives, we have a home in progress on an acre of land--plenty of space for a garden and an "antenna farm." All my years of frugality are finally paying off.  Your tips and suggestions have enabled me to assemble a "ham" station and a set of modest antennas at a relatively modest cost.

Second, a good year from the amateur radio standpoint comes from a rededication to the original "Amateur's Code" conceived by Paul Segal (W9EEA) back in 1929.  The code embodies all that an amateur radio operator should stand for:  An amateur radio operator should be considerate, loyal, progressive, friendly, balanced, and patriotic.  These ideals, while difficult to attain, are at the core of a civilized society.  These are goals worth striving for, no matter what part of the world you call home.  I will try my best to implement these guideposts in my daily life, whether or not I'm on the air.

Third, safety will be a guiding principal of my amateur radio activities, both in my home and at the rig.  Every year I make sure that all safety devices at my qth and in the radio room are working and well-maintained, including the smoke/fire alarms, fire extinguishers, house wiring, and security systems.  At least twice a year, I make sure tree limbs and other debris are clear of utility lines.  On Hawaii Island, the Hawaii Electric Light Company (HELCO) will come to island homes and clear away dangerous limbs from utility lines.  All one has to do is call for help.  In the radio room, I make sure all equipment is clean, dust-free, and maintained to the best of my ability.  I also make certain that there is both an electrical and rf ground system in place.  All electronic equipment, including transceivers, general purpose receivers, television set, stereos, DVD/CD players, and personal computers are hooked up to surge protectors.  When the xyl and I leave the house, we unplug all equipment not in use.

Fourth, all antennas used at the current qth and at the new home site will be better protected against lightning and other storm-related events.  When I finish operating for the day, I disconnect all antennas from the rig and ground the feed lines (coax and ladder line) outside.  My vertical antennas are nested to the ground after use to lessen both the danger of lightning strikes and the discovery by neighbors.  In January, all of my antennas will have a static discharge system in place to lessen inadvertent damage to my solid state equipment.

Fifth, I will expand my alternative power supply for my amateur radio equipment.  Presently, I can operate off the regular electric mains and a backup solar- charged (PV) deep cycle marine battery.  I will convert to a complete "off-grid" power system early next year.  I have enough money to buy some more solar panels, a new deep cycle marine battery, a new trickle charger (if needed), and an inverter.  Also in the works is the purchase of a small Honda generator for additional backup power.

Sixth, I plan to renew my American Red Cross CPR and First Aid Certificates.  I'm also considering taking some CERT or FEMA courses to sharpen my emergency communications skills.  Because of past work requirements and other demands, I was unable to help my community as fully as I wished.  Now, in retirement, I've got the time to become proficient in vital skills and, therefore, a better asset to the local civil defense agency.

Seventh, I will help more people get licensed as amateur radio operators.  I'm a current W5YI Volunteer Examiner and have helped monitor a few amateur license exams.  I plan to do more in this area during 2014.

Finally, I will get on the air more than I have in 2013.  With the house move underway and my teaching commitments, it's been difficult checking into nets and going to Big Island Amateur Radio Club meetings.  That will change now that my teaching schedule is more predictable.  Hawaii Island is fortunate to have several ham radio clubs that are active in ARES and other community-related programs.

For me, and perhaps for you, amateur radio is not a destination.  It's a journey to an expanding universe of knowledge.  Our license is only the first step in seeing the future.  Good luck in the coming year and may the winds of DX blow your way.

Listed below are some of the places where you can get some ideas for 2014:

The Amateur's Code may be found by visiting http://www/qcwa/prg/amateur-code.htm.
http://www.techpodcasts.com/myamateurradio/127182/parp-65-amateur-radio-goals-for-the-new-year.
http://www.arrl.org/Groups-Nebraska.
http://www.humanresources.about.com/od/motivationsuccess3/a/new_resolutions_2htm.
http://www.forums.qrz.com/shorsthread.php?417314-New-Year-s-Resolutions-Become-a-CERT-Leader.

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.




Wednesday, December 25, 2013

Simple Ham Radio Antennas--going stealth mode. Post #250.

For most of my 36 years as an amateur radio operator, I've had to operate under the limitations imposed by HOAs, CC&Rs, and postage stamp sized backyards.  Like many of you, my creativity was sorely tested  as I tried to get reasonably efficient antennas erected for my home station.  In many cases, one antenna had to suffice for multiband operation.  And that antenna had to be inconspicuous, easy to erect and take down, and not present an "eyesore" to the neighbors.

Over the course of those years, I managed to enjoy ham radio despite the highly compromised antennas and low power employed at the shack.  There were a few multiband designs which proved successful for local and occasional DX.  Among them were inverted vees and 1/2 wavelength horizontal dipoles fed by 450 ohm ladder line connected to a 4:1 balun and a Drake MN-4 antenna transmatch.  When I did have a bit more space, I used full wavelength loops fed by ladder line for 20, 15, and 10 meters.  Height above ground was always a problem owing to the lack of nearby trees or other structures.  So, early on I bought several telescoping fiberglass masts which extended to 33 feet/10.06 meters.  These masts were easy to erect, take down, and store.  With a pulley and lanyard system, I could hoist pre-made antennas for single or multiband use in a matter of seconds.  The antennas were nested to ground level after use, lessening the impact on the local "environment."  My antennas were largely "out of sight, out of mind" since I operated mostly at night.

I generally avoided vertical antennas because I lacked sufficient space to lay in a decent ground radial system.  A vertical antenna depends on a ground radial system to function efficiently.

While I did enjoy working on these temporary antennas, I felt the need for more space so I could erect more permanent, full-sized  antennas for the bands I favored.  In May, my xyl and I bought a nice home on an acre of land in the sprawling Puna District of Hawaii Island.  At last, there was sufficient space to erect antennas for each amateur radio band.  The antenna "farm" is slowly taking shape--a project that will take a few months to complete.

Meanwhile, both of us are still living in a nice rental home in Laupahoehoe along the Hamakua Coastline. The house is quite nice, but it's confined by high voltage lines, numerous neighbors, and very little backyard space.  I needed a temporary, largely invisible antenna to continue my amateur radio activities while we gradually moved into the new place.  Most of the antennas I had used here were already packed away and stored at the new qth.

After a few days of research in my antenna books, the ARRL archieves (members only), and some inquiries into a few antenna websites, I found an antenna which is both "stealthy" and useful for my mostly local and regional contacts--a 40 meter full wavelength loop strung under the house and fed by 450 ohm ladder line connected to a 4:1 balun and my trusty Drake MN-4 transmatch.  Last year, I used this low-lying loop to good effect on the local Hawaiian Afternoon Net.  The loop is basically a NVIS (near vertical incident skywave) antenna that puts a strong signal out to about 300 miles/approximately 480 km--more than enough to cover the entire Hawaii Island chain.  So, I decided to reinstall the loop.  I'm glad I did.

My rental house is built on a pillar and pier system to withstand minor earthquakes and flooding.  The house is approximately 5 feet/1.82 meter above ground.  The loop can be squeezed around the perimeter of the house and part of the garage.  

MATERIALS:

Using the general formula 1005/f (MHz)=L (feet), I cut the 40 meter loop to a length of 142.55 ft/43.46 meters.  I used some #22 AWG hookup wire stored in the garage for the antenna.  The resonant frequency of the loop would be 7.088 MHz, the "watering hole" for the Hawaii Afternoon Net.

A box of push pins to secure the wire to the underside of the house.

One ceramic insulator to support the junction of the loop and the 450 ohm feed line.  The insulator would be attached to the underside of the living room floor about 5 feet/1.82 meters above ground level.  The feed line connections were soldered and covered with several layers of vinyl electrical tape.

Twelve feet/3.65 meters of 450 ohm ladder line.

One W9INN 4:1 balun.

Three feet/0.91 metes of RG-8X coaxial cable with UHF connectors.

Transceiver (Swan 100 MX).

Dummy load.

Drake MN-4 transmatch.

Low pass filter. Some of my neighbors get their television programs over the air.

Various coaxial patch cords to interconnect station equipment.

ASSEMBLY:

The antenna assembly is simple and takes only a few minutes.

I attached the 40 meter loop around the perimeter of the house and part of the garage.  Push pins secured the loop to the underside of the house.

The 450 ohm ladder line was attached to each end of the loop.  Connections were soldered and covered with vinyl electrical tape.

The ladder line was inserted under the back door and led into the living room where it was connected to the W9INN balun. The balun was approximately 3-feet/0,91 meters from the Swan 100 MX transceiver.

A 3-foot/0.91 meters length of RG-8X coaxial cable was attached to the balun and then connected to the Drake MN-4 antenna transmatch.  The Swan 100 MX was connected to the Drake MN-4 along with the dummy load and the low pass filter.

INITIAL RESULTS:

As expected, the under-the-house loop used  in conjunction with the 4:1 balun and the Drake MN-4 transmatch covered all amateur radio frequencies between 40 and 10 meters with a low swr (below 1.3 to 1).  Since the antenna was a NVIS design, most of the signal went straight up and covered the state of Hawaii from Kauai to Hawaii Island with SSB reports ranging from 57 to 59 using approximately 20 watts from the old Swan 100 MX.  In most cases, I will not exceed this power level because of rf and safety concerns.  When I use CW, the power level is held to 10 watts or less.  I've had a few mainland U.S. contacts on 40 and 20 meters with reports running between 55 and 57.

Given the self-imposed height and power restrictions, this low-lying loop is providing the performance I need until my antenna "farm" is done at my new qth.

The under-the-house 40 meter loop supplements the 80-foot/24.39 meters loop I have tacked around the interior of my rental home.  In any case, these antennas, when operated at low power levels, provide many hours of enjoyment without undue interference to computers, televisions, or entertainment systems.  

The new loop is invisible to neighbors, requires no ground system, and easily erected and taken down.

Perhaps a loop antenna is in your future.

REFERENCES:

http://www.g4ilo.com/stealth.html.
http://www.dxzone.com/catalog/Antennas/Stealth.
http://www.arrl.org/shop/Stealth-Antennas.
http://www.sgcworld.com/Publications/Books/stealthbook.pdf.
http://bvarc.org/pdf/HF_Antennas_by_KD5FX.pdf.
http://www.hamlearningnet.org/dl/Stealth_Antennas.pdf.

Thanks for joining us today.!

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

Happy Holidays!

Russ (KH6JRM)
BK29jx15
Along the beautiful Hamakua Coast of Hawaii Island.

Friday, December 20, 2013

Simple Ham Radio Antennas: A multiband Inverted-V Antenna. Post #249

One of the most popular amateur radio antennas is the Inverted-V.  This antenna is a first cousin to the half wavelength horizontal dipole whose antenna elements are drooped down so that the included angle between them is between 90 and 120 degrees.  According to William I. Orr (W6SAI) and Stuart D. Cowan (W2LX), the "bandwidth is somewhat lower than for a conventional dipole...Because the wires of the Inverted-V do not lie along one axis, the physical length is somewhat longer than that of a dipole cut for the same frequency."  For general design purposes and allowing for some trimming of antenna elements, you can use the general dipole formula, 468/f (MHz)=L (feet) to compute the total length of the Inverted-V dipole.  Some antenna experts believe the drooping halves of the Inverted-V change the resonant frequency, and, therefore, recommend a slightly different formula be used to calculate the length, such as 464/f (MHz)=L (feet).  I use the 468/f (MHz)=L (feet) formula to establish a general length parameter and use the old "cut and trim" method to bring the antenna to resonance on my chosen frequency.  More often than not, I cut a compromise length and use my trusty Drake MN-4 transmatch to take care of the small SWR found on the feed line.

Allowing for some performance shortfalls, the Inverted-V has some definite advantages:

Only one support structure is needed.

No ground radial system is required.

The Inverted-V can be fed with 50 ohm coaxial cable for single band use or fed with 300 ohm television twin lead or 450 ohm ladder line for multiband use.

The Inverted-V is simple to build, inexpensive, and portable.

I've used a variety of single and multiple band Inverted-Vs in my amateur radio "career" with excellent results. Now that I'm moving to a new home site with plenty of room for antennas, I thought a few antenna experiments would be in order.

In previous posts, I've related my adventures with homebrewed delta loops, vertical ground planes, doublets, and even double extended zepp antennas.  All of these antennas have worked very well, even at power levels below 10 watts.

My recent foray into antenna territory has been the construction of a multiband Inverted-V covering the 80, 40, and 20 meter bands.  Unlike some of my other antennas, I didn't use tuned feeders because my stock of 450 ohm ladder line was exhausted.  I did, however, have several 50-foot/15.24 meters lengths of RG-8X coaxial cable with UHF connectors.  Properly designed, a coaxial feed line can be used to cover several bands if "outrigger" segments for each additional band are attached to the main Inverted-V dipole.  Since I would be covering 80 meters as the lowest band, the principal V would be cut for 3.800 MHz.  Subsequent segments would be cut for 40 and 20 meters and connected  by ceramic insulators and alligator clips to constitute a workable antenna for each respective band.

A design attributed to Ed Noll (W3FQJ) provides a series of clip on jumpers for operation of the 80 meter Inverted-V as a 5/2 wavelength antenna on 20 meters and as a 3/2 wavelength antenna  on 40 meters.  The 80 meter antenna is cut as a 1/2 wavelength antenna with various segments added to bring bring each band into resonance.  A single 50 ohm feed line is connected to the top of the mast where the 80 meter elements are attached.

MATERIALS:

The antenna was built on the ground and later hoisted to the top of a mast by means of a pulley and lanyard system.

One 33-foot/10.06 meter MFJ telescoping fiberglass mast.

One 5-foot/1.82 meters wooden support stake for the mast.

Approximately 225 feet/68.59 meters of #14 AWG housewire.  The wire will serve as 80 meter antenna elements and as the 20 and 40 meter outrigger segments.

One Budwig HQ-1 center insulator.

Six ceramic insulators to tie off and join outrigger segments to the main 80 meter antenna.

Four, 5-foot/1.82 meter wooden stakes to support the outrigger segments.

Fifty feet/15.24 meters of RG-8X.  This will be the antennas feed line.

One Drake MN-4 antenna transmatch to handle the small amount of SWR on the feedline.

Station equipment, including a Swan 100 MX transceiver, dummy load, and low-pass filter.

Various 3-foot/0.91 meters lengths of RG-8X cable for connecting equipment to the Drake MN-4 transmatch.

ASSEMBLY:

First, I cut the 80 meter dipole according to Ed Noll's (W3FQJ) instructions. Each dipole element measured 62 feet, 2.5 inches/18.98 meters.  

I attached and soldered the top end of each 80 meter element to the Budwig HQ-1 center connector.

I attached a clip lead to the bottom end of each 80 meter element and secured that connection to a ceramic insulator.

Next, I cut each element of the 20 meter segment to a length of 21 feet, 3 inches/6.48 meters.  I attached a clip lead to each end of the 20 meter segments and threaded them through the end insulators of the 80 meter elements.  I then attached  clip leads to the other end of the 20 meter segments and threaded them through ceramic insulators.

I then cut each element of the 40 meter segment to a length of 16 feet, 0 inches/4.87 meters.  A clip lead was attached to one end of each segment and threaded through the end insulators of the 20 meter segments.

To use 80 meters, I left all clip leads unattached.  To pursue DX on 20 meters, I connected each 20 meter segment to each 80 meter element.  This connection would serve as a 5/2 wavelength antenna for 20 meters.  To chase local contacts and occasional DX on 40 meters, I connected all of the segments together. The arrangement would serve as 3/2 wavelength antenna on 40 meters.

With the 80 meter antenna and all of its outrigger segments joined by clips and ceramic insulators, I attached the Budwig HQ-1 coax connector to the apex of the mast.  I then hoisted the mast onto its wooden support stake.

Five-foot/1.82 meters wooden support stakes were attached to the insulators joining the 80 and 20 meter segments and the 20 and 40 meter segments.  The wooden stakes kept the outrigger segments off the ground and limited antenna sag.

INITIAL RESULTS:

Without the Drake MN-4  transmatch in the antenna system, I was able to get a SWR of less than 2:1 across all portions of 20 and 40 meters.  Although I was able to get a decent SWR in the neighborhood of 3.800 MHz, it was not possible to cover the entire 80 meter band without the aid of the Drake MN-4.  With the transmatch in the line, I was able to get an acceptable match on most of the 80 meter band.  The transmatch kept the SWR below 1.3 to 1 on the 20 and 40 meter bands. 

As an experimental multiband antenna, the segmented Inverted-V performed well at my home site in the Puna District.  To change bands, all I have to do is lower the Inverted-V and change the clip leads.  Since I had all the antenna materials on hand, my cost was minimal.  You can use this outrigger design for any bands you desire.  Have fun!

REFERENCES:

Orr, William I. (W6SAI) and Cowan, Stuart D. (W2LX).  The Radio Amateur Antenna Handbook.  Radio Publications, Inc.  Lake Bluff, Illinois, 18044.  Seventh Printing, 1988. pp. 131-133.

Orr, William I. (W6SAI) and Cowan, Stuart D. (W2LX).  Simple, Low-Cost Wire Antennas.  Radio Publications, Inc.  Winton, Connecticut, 06897.  Fifth Printing, 1979.  pp.70-86.

McCoy, Lew (W1ICP).  Lew McCoy On Antennas--Pull Up A Chair and Learn From the Master.  CQ Communications, Inc.  Hicksville, New York, 11801.  Second Printing, 1977.  pp. 51-52.

Turner, Rufus P.  The Antenna Construction Handbook for Ham, CB & SWL.  Tab Books, Inc.  Blue Ridge Summit, Pennsylvania, 17214.  Second Printing, 1981.  pp. 91-92.

The ARRL Antenna Book.  American Radio Relay League, Inc.  Newington, Connecticut, 06111.  Fourteenth Edition, Second Printing, Copyright 1983.  pp. 8-9 and 8-10.

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

Thanks for being with us today!

Aloha de Russ (KH6JRM)

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
















Saturday, December 14, 2013

Simple Ham Radio Antennas: A double extended "zep" for 10 meters. Post #248.

From what I've been hearing today (Saturday, 14 December 2013), amateur radio operators are having a good time on the ARRL 10 meter contest.  Although propagation has been variable on Hawaii Island, the band seemed alive with signals.  Ten meters, like its distant cousins at 160 meters and 6 meters, offers plenty of challenges for amateurs new and old.  When propagation is favorable, both local and DX signals are possible with low power and modest antennas that can fit into a small backyard.

Ten meter events are scheduled throughout the year, sponsored by the ARRL, various national amateur radio groups, and the Ten-Ten group, which promotes the use of 10 meters.

Antennas for 10 meters run the gamut from multi-element beams and ground planes to dipoles and full wavelength loops.  Even though the current ARRL 10 meter contest is coming to an end, it's not to early  to think about ways to improve the signal from your 10 meter antenna.

If you want some gain over a dipole and have about 50 ft/15.24 meters of horizontal space, why not build a double extended zepp antenna for your next 10 meter operation?  The antenna traces its ancestry both to the familiar half wavelength dipole and to the trailing antennas used on the Zeppelin airships of the 1920s and 1930s.

The double extended zepp looks like a conventional halfwave dipole fed in the center with 300 or 450 ohm feed line.  But, unlike the horizontal flat top known to most of us, each antenna element is 5/8 of a wavelength long, which produces a gain of approximately 3 dB over a dipole at the same height.  According to Steve Shorey (G3ZPS), this gain is attained when the extended zep is approximately 0.6 wavelength above ground.

Just before the ARRL 10 meter contest, I built a crude replica of a double extended zepp at my future homesite in the Puna District.  So far, the antenna works very well and gets better reception reports than my 10 meter ground plane.

Here's what I did to make the antenna:

Using the formula 599/f(MHz)=l (ft) supplied by Steve (G3ZPS), I cut two equal lengths of #14 AWG housewire for a chosen frequency of 28.400 MHz in the 10 meter band.  This frequency is quite busy, with many newly licensed technician class licensees testing the waters of SSB operation.  These contacts are always interesting and remind me of the time I first ventured into a "phone" band.  Based on this general formula, each element of the zepp measured 21.09 ft/6.43 meters.

Once I had cut the wire, I began to assemble the antenna on the ground.

I used three MFJ telescoping fiberglass masts to support the antenna.  One mast would support the center connector and the 450 ohm ladder line, while the other two masts would support the zepp elements.

The masts extended out to 33 ft/10.06 meters.  At this height, the zepp would be more than 0.6 wavelength above ground and should give me about 3 dB gain over my 10 meter inverted vee and ground plane.

Three, 5-ft/1.52 meters wooden support stakes for the masts.  Each mast had a halyard and pulley system which would allow me to hoist each section of the antenna to its proper height.

I attached a ceramic insulator to each end of the elements.  A short piece of dacron rope would be used to tie off the insulator to each mast.  The tie off rope was approximately 3 ft/0.91 meters long.  The center connector was the "ladder lock", a device that allows you to attach each wire of the feed line to its respective antenna element.

The ladder lock was secured to the center mast with nylon ties and duct tape.  The ladder line was run down to the midpoint of the center mast (16.5 ft/5.03 meters) and secured to the mast with nylon ties.  All antenna connections were soldered and covered with several layers of vinyl electrical tape.  

I attached each element of the antenna and the center connector to its respective pulley and halyard system.

After each mast was hoisted into position on its support stake, I raised each antenna element to the apex of its mast and tied off the halyard to the base of each mast.  To make adjustments, all I would have to do is raise or lower each element with the halyard and pulley system.

Once I had the masts in place, I ran 50 ft/15.24 meters of 450 ohm feed line to a W9INN 4:1 balun attached to the garage wall (approximately 16.5 ft/5.03 meters above ground at the peak of the garage roof).  The only dangerous part of this installation was using a ladder to get the balun near the top of the roof peak.  A neighbor, who doesn't mind about my amateur radio operations, steadied the ladder while I attached the feed line to the 4:1 balun and ran 25 ft/7.62 meters of RG-8X coaxial cable with UHF connectors through the patch panel in the shack window.

The balun was wrapped in thick plastic to protect the device from the weather.

Once the coax was safely inside the shack, I hooked up the Drake MN-4 transmatch, the Swan 100 MX transceiver, and the dummy load to complete the project.

Based on just a few contacts  Friday (13 December 2013), the double extended zepp works very well with SSB reports running between 56 and 58, using approximately 50 watts output from the old Swan 100 MX. The antenna was oriented northwest to southeast, giving me some decent coverage of the U.S. mainland.

As an added bonus, the ladder line/balun/transmatch combination allows me to transmit a usable signal with low SWR on 20, 15, and 10 meters.  While not a competition grade antenna, it does perform better than my reference 10 meter ground plane and gives me some gain to mainland U.S. areas.  I can change the directivity of the signal by moving the masts, so that the broadside pattern and its lobes reach other parts of the compass.

If you need a new antenna for 10 meters, try a classic double extended zepp.  It's cheap, easy to make, and produces results at modest power levels.

REFERENCES:

home.comcast.net/~n8itf/doublezepp.htm.
http://www.g3zps.com/Page4.htm.
myplace.frontier.com/~nb6z/nb6zep.htm.
rudys.typepad.com/ant/files/antenna_colinear_zepp.pdf.

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

For the latest amateur radio news, please visit my news site--http://kh6jrm.com.  I've included a few news headlines at the bottom of this post.

Thanks for being with us today!

Aloha de Russ (KH6JRM)

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




Friday, December 6, 2013

Simple Ham Radio Antennas--a multiband indoor loop antenna. Post 247

Over the past few posts I've been recounting the joys of erecting antennas with no space restrictions.  On my new property in the Puna District of Hawaii Island, I have an acre of land with few close neighbors and a comfortable distance from the Keaau to Pahoa Highway and all of the power lines following that road.

However, for most of my 36 years as an amateur radio operator, I've had to erect compromise antennas because of space limitations, proximity to high voltage power lines, and the eyes of suspicious neighbors.  Most of these antennas worked very well, considering the space restrictions of my rental housing.  One thing I did discover is just how good a basic 1/2 wave length horizontal dipole or inverted v performs when you use a moderate length mast (33 ft/10.06 meters) coupled with 450 ohm feed line, a 4:1 balun, and a decent transmatch.  This combination gives you multiband capability with the design frequency being the lowest band you wish to use.

I've also used a variety of indoor antennas, ranging from the commercially bought MFJ-1622 vertical with tapped coil and counterpoise to homebrew loops fed with 300 ohm tv twin lead or 450 ohm ladder line.  I was able to get many contacts with these antennas, despite their small size and proximity to electronic devices in my former homes.

While I'm moving to my new location (it will take a few months in between teaching assignments), most of my backyard antennas at my Laupahoehoe qth have been lowered, packed away, and taken to the new home site.  The under-the-house 40 meter loop is still available for local and statewide contacts.

Until I get all of my antennas erected at the new location, I'll have to make do with some temporary antennas.  Since I've had good results with HF loop antennas, I decided to make another HF loop to supplement the existing loop under the shack.  This time, I put the loop inside the house, tacked to the ceiling of the living room and fed with 450 ohm ladder line into a 4:1 balun connected by a short piece (3 ft/0.91meters) of RG-8X coaxial cable to my trusty Drake MN-4 antenna transmatch.  For reasons of rf exposure and safety, I decided to use my portable qrp rig (Yaestu FT-7) as the transceiver.

ASSEMBLY:

Using valuable information from "Yukon John" (KL7JR) and Scott (K2ZS), I decided to use an 80 ft/24.39 meters loop fed by ladder line into a 4:1 balun and a sturdy antenna transmatch (Drake MN-4).  The antenna would give me 20 through 10 meter coverage at minimal cost and reduced rf exposure.

I had some spools of #22 AWG hookup wire in the garage, a package of  push pins in the shack desk drawer, 10 ft/3.04 meters of 450 ohm ladder line in the desk drawer, a W9INN 4:1 balun on the workbench, and the Yaesu FT-7 in the van.

In his article on stealth loops, K2ZS suggested a length of 70 to 90 ft/18.29 to 27.43 meters for the indoor loop.  I chose a compromise value of 80 ft/24.39 meters because that fit the dimensions of my large living room.

Using a small ladder for support, I used push pins to attach the loop to the living room ceiling.

The 450 ohm ladder line was soldered to each end of the loop.

The ladder line was dropped straight down to the floor.  The ladder line was connected to the W9INN 4:1 balun.  Three feet/0.91 meters of RG-8X coaxial cable with UHF connectors was attached to the balun and run into the Drake MN-4 transmatch.  Short patch cores made from RG-8X coaxial cable (about 2 ft/0.06 meters long) were used to connect the dummy load, low pass filter, and transceiver to the antenna transmatch.

To minimize rf interference to our home computer and entertainment systems, I only operate during the afternoon or late evening when our use of the entertainment equipment is minimal.  I also keep the power below 10 watts and operate primarily CW.  So far, I've encountered no rf problems in the house.  I do have a good supply of torroids to use on power and computer cables should the need arise.

RESULTS;

The indoor loop works very well on 20 through 10 meters.  My CW reports range from 549 to 579 depending on propagation.  On the occasional SSB contact, I get reports between 54 and 57.  My low power signal won't break a DX pileup, but, for casual contacts and local rag chews, the indoor loop is adequate until my final move out to the Puna District.

Best of all, I don't need a counterpoise to run along the baseboards of the floor. 

I'll try out this indoor loop during the upcoming ARRL 10 meter contest (14-15 December 2013).

This indoor antenna was fun to build and cost me practically nothing.

REFERENCES:

http://www.hamuniverse.com/kl7jrindoorloop4010.html.

http://www.arrl.org/indoor-antennas.

http://www.k2zs.com/indoor-antennatips.

http://www.iw5edi.com/ham-radio/?hf-ham-radio-antennas-for-apartments%2C53.

http://www.g4ilo.com/stealth.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.
 

Friday, November 29, 2013

Antenna Safety. Post #246

In the excitement of designing, building, and erecting my "homebrew" wire antennas, I've often neglected to consider important safety issues which could affect the location of my antenna and perhaps save my life.
A few years ago, I erected a vertical antenna which gave me excellent service until a lightning strike turned my work of art into a mess of shattered fiberglass, pvc pipe, wire fragments, charred coaxial cable, and a severely damaged ego.  Fortunately, I had disconnected the feed line from my shack and had it connected to a ground rod.

Ever since that lucky escape from Mother Nature, I've had a firm respect for the weather and "Murphy's Law" (whatever will go bad will fail at the most inconvenient time).

Over the course of my amateur radio "career", I've followed a few basic guidelines to erecting antennas, whether they be commercially bought or built from my own resources.

PLAN AHEAD

I know this sounds pretty basic, but thoroughly outlining your antenna project, assembling all of the parts beforehand, and doing a general survey of your property for hidden dangers can pay big dividends later.

Before I build an antenna, I walk over the area for the proposed antenna site.  I note any safety hazards such as uneven ground (especially dangerous when you have to disconnect your antenna at night), proximity to power, telephone, and cable lines, and visibility concerns (there's always someone who hates antennas and will tell the world about it).

After I'm done with my initial inspection, I ask someone else (my xyl or another ham) to look around for anything I might have missed.  Another set of eyes is always helpful in picking out questionable objects on the antenna field.

I also draw a rough diagram of the proposed antenna and its placement on the property.  This drawing is filed in my antenna notebook and will be used to make revisions to the design.

Once the basic plan is drawn and the property checked for suitability, I then advance to the second phase of the antenna project.

BASIC SAFETY ASSUMPTIONS

Assume that everything connected to the antenna structure is conductive.

Assume that the antenna or any part of it, including supporting masts, guy lines, feed lines, and antenna elements will fail or break at the most inconvenient moment.  Be sure your construction is sturdy and can stand up to the weather.

Antennas should be kept far away as possible from utility lines, both from the pole carrying the energized lines and the entrance of these wires into your home and shack.  At my current location in a crowded neighborhood, I've had to resort to small verticals and low slung dipoles and loops to maintain a safe distance from power lines.  At my new home in the Puna District, my nearest antenna structure (a 33-ft/10.06 meters fiberglass mast) is about 100 ft/30.48 meters from the nearest utility line or cable entrance.

If possible, lower your antennas to ground level after you are done operating.  This will present less of a target for lightning or snoopy neighbors.

Disconnect all antenna feed lines from your equipment when the operating day is over.  I use a window patch panel to run coaxial or ladder line feeders into the shack.  The external leads are connected to an 8 ft/2.43 meters ground rod at the base of the antenna mast.  A set of four, 33 ft/10.06 meters radials are connected to the ground rod and form a spoke pattern around the base of the antenna.

Be sober when you build and erect your antenna.  Alcohol and antenna building are a bad combination, especially if you are erecting a tower.

If you are uncertain about erecting a mast or tower, get help from your local amateur radio club.  Even if you are working alone on a simple vertical, be sure you have safety equipment for use, including gloves, hard hat, and good work boots.  If your project involves the use of a tower, be sure to get climbing belts and other tower climbing equipment.

If you are using a commercial antenna, be sure to follow all instructions and procedures exactly.

Be sure you have a written outline of how the antenna erection will  proceed. Give copies to your antenna crew if you have one.  Include in your plan the procedures you'll use to correct any failure of equipment or parts.  Before you erect your antenna, do a "dry run" of the antenna construction and raising.

If at all possible, build as much of the antenna on the ground as you can.

If you'll be using a mast to support your dipole, inverted v, or vertical, install a simple halyard-pulley system on the mast to raise or  lower the antenna should the need arise.  This system will come in handy for antenna adjustments or to lower the antenna during bad weather.

Avoid bad weather, especially storms with thunder and lightning.  Build and erect your antenna during a calm, sunny day if possible.  The antenna can wait.  Your life won't mean much if you're in the way of a lightning strike.

OTHER THOUGHTS

When I get through working DX or some laid back local contacts, I always do the following:

Disconnect antenna feed lines and connect them to the ground rod at the base of the antenna.

Unplug all station equipment.

Install a static discharge system on your antenna feed lines.  While this step won't protect you from a direct lightning strike, it will "bleed off" static electricity that builds up on antennas.  Some of the newer solid state transceivers are quite sensitive to electrical discharges.

There are probably many other steps you can take to insure a safe, efficient antenna system.  I've listed a few articles which explore antenna safety issues in depth.  These essays are worth reviewing.  Good luck in your next antenna project.

REFERENCES

http://www.arrl.lorg/files/Technology/tis/info/pdf/016091.pdf.
http://www.universal-radio.com/catalog/wideant/safewide.html.
http://www.hamuniverse.com/antennasafety.html.
http://www.cisco.com/en/US/docs/wireless/bridge/350/installation/guide/BR350apC.html.
http://www.k2zs.com/indoor-antenna-tips/constructiontips.

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

Thanks for joining us today.

Aloha de Russ (KH6JRM).

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




Monday, November 25, 2013

Simple Ham Radio Antennas: The sloping 30 through 10 meter delta loop. Post #245

How would you like to build a simple, effective antenna for 30 through 10 meter coverage with some gain over a dipole at a moderate cost?  The answer is as simple as designing, erecting, and using a sloping delta loop antenna designed for 30 meters and fed with 450 ohm ladder line into a 4:1 balun connected to a sturdy antenna transmatch.  The ladder line will permit you to cover frequencies between 10.100 MHz through 29.7 MHz with low SWR.  You can also design the antenna for 30 meter use only by feeding the antenna with 50 ohm coaxial cable in conjunction with a 1/4 wavelength matching section made of 75 ohm coaxial cable.  The latest ARRL Antenna Book has more details on how to make the matching section should you decide for that option.

Now that I have more room for my expanding "antenna farm" at my new home site in the Puna District of Hawaii Island, I can set aside some space for antenna experiments without worrying about HOAs, CC&Rs, or unsympathetic  neighbors.  For many years, I've had to use compromise antennas at my amateur radio station.  They all worked well considering the severe space restrictions at my present location.  Once I complete the housing move next year, I'll have enough room to erect some decent antennas.  I already have a few antennas in place--most of them are well disguised by the tall trees surrounding my property.

Over the past few years, I've found the 30 meter band a welcome escape from the heavily used 20 and 15 meter bands.  The 30 meter amateur radio band is the place for the cw and digital signal enthusiast.  Even with the modest 30 meter sloping dipole I made a few weeks ago, contacts were easy to manage and the band was full during my early morning and late afternoon operating hours.  I wanted to try a full wavelength loop on this interesting band.  I've always enjoyed full wavelength loops because of their modest gain over a dipole, fairly quiet operation, and ease of construction.  With the considerations mentioned in the opening of this post, I decided to build a simple sloping delta loop for 30 meters in back of my Puna District home.  The loop would be used for frequencies ranging from 10.100 MHz to 29.7 MHz, with the main design frequency set for 10.125 MHz--the midpoint of the band.  With 450 ohm ladder line, a 4:1 balun, and my trusty MFJ 941E Versa Tuner antenna transmatch, I could roam around several bands without worrying about excessive SWR.

I started the project early this morning before the arrival of the afternoon showers predicted by the National Weather Service.  I had the following materials on hand:

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

Three 6-ft/1.82 meters wooden stakes.  One stake would support the fiberglass mast.  Two stakes would support the bottom of the delta loop.

One "ladder lock" connector to support the 450 ohm ladder line and its attachment to the delta loop at the apex of the fiberglass mast.

Two ceramic insulators attached to wooden stakes at the bottom of the delta loop.  The wire would run from the mast apex through the insulators.  Small lengths of dacron rope would tie off the insulators to the stakes.

Fifty feet/15.24 meters of 450 ohm ladder line.  This would serve as the antenna feed line.

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

One W9INN 4:1 balun.

One MFJ 941 Versa Tuner antenna transmatch.  Unfortunately, my Drake MN-4 wasn't configured to work on 30 meters.  The old Versa Tuner has given good service as a standby transmatch.

One Ten Tec Argosy II transceiver.  This is the only rig I have that can access 30 meters.

One solar charged deep cycle marine battery to serve as a power supply.

Basic tools, nylon ties, soldering gun, tape, etc.

Enough wire to make a full wavelength antenna for 30 meters.  Using the general formula 1005/f(MHz)=L(ft) and #14 AWG housewire, I cut the antenna for a resonant frequency of 10.125 MHz (the band midpoint). The total length of the antenna came out to 99.25 ft/30.26 meters.  Each side of the three-sided delta loop would measure 33.08 ft/10.08 meters.

ASSEMBLY:

The antenna was built on the ground.

I attached the top of the delta loop to the 450 ohm ladder line with the "ladder lock" device.  The center connector was secured to the top of the fiberglass mast with a short piece of dacron rope.  All connections were soldered and wrapped with several layers of vinyl electrical tape.  The "ladder lock" device with the 450 ohm feed line and its connection to the top of the delta loop was secured to the top of the mast with several nylon ties.  I ran the ladder line down the mast approximately 5 feet/1.52 meters.  I tied off the ladder line to the mast with another nylon tie.

I hoisted the fiberglass mast onto its 6 ft/1.82 meter wooden support stake.

I led the delta loop off at a 45-degree angle from the mast and secured the bottom portion of the delta loop to two 6 ft/1.82 meters wooden support stakes.  The antenna wire was threaded through 2 ceramic insulators, which were attached to the wooden support stakes by 2 inches/5.08 cm of dacron rope.

The delta loop was adjusted for a uniform shape.  The loop was configured as a sloper with the apex of the loop attached to the top of the mast and the two sides swung out at an angle and secured to wooden support stakes. Since the bottom of the delta loop is close to the ground, I attached yellow warning tape along the bottom element of the loop.

The 450 ohm ladder line was led to the W9INN 4:1 balun attached to the garage wall in back of the house. The balun is mounted approximately 6 ft/1.82 meters above ground.

Twenty-five feet/7.62 meters of RG-8X coax with UHF connectors were attached to the balun and run through a window patch panel in the garage.  The coax was then connected to the MFJ 941E Versa Tuner. Short lengths of RG-8X coaxial cable interconnected the Ten Tec Argosy II transceiver to the transmatch, low pass filter, and the dummy load.

After 2 hours of leisurely work, the antenna was done.

INITIAL RESULTS:

Thanks to the MFJ 941E Versa Tuner, I was able to keep SWR near 1.1 to 1 between 10.100 MHz and 29.7 MHz.  I made a few 30 meter contacts late this afternoon, with reports ranging between 569 and 599 using the Argosy II running approximately 20 watts.  Contacts were also made on 20 and 15 meters, with SSB reports ranging from 56 to 59 on 20 meters and 54 to 56 on 15 meters.  Again, power used was near 20 watts from the Argosy II.  I'm sure a little tweaking will be necessary to get the most out of this antenna. So far, results have been satisfactory.  For a homebrewed antenna made from available parts, I really can't complain. Most of the materials can be bought at the nearest hardware store.  You can also substitute pvc pipe, surplus military mast sections, or even a high tree branch for the mast.  This antenna is simple, cheap, and a joy to use.

REFERENCES:

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

http://www.wikihow.com/Build-Several-Easy-Antennas-for-Amateur Radio.  See section 20 for loop antenna ideas.

http://www.southgatearc.org/articles/g0ftd/loop_antennas/simple-loop-antennas.htm.

http://arrl.org/hf-loop-antennas.

http://www.youtube.com/watch?v=y3-LIQ6G6e4.

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

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Saturday, November 23, 2013

Simple Ham Radio Antennas--the 40 meter NVIS loop. Post #244

In this age of natural and man made disasters, it's important to have back up equipment, antennas, and power available during periods of emergencies.  A set of homebrewed wire antennas can keep you on the air when your beam or tower have been damaged by forces beyond our control.

One of the best standby antennas is the NVIS antenna, which, because of its portability and ease of operation, can be tucked away in a convenient spot for future use.  NVIS (near vertical incident skywave) antennas are perfect for local or regional use out to about 300 miles/480 kilometers.  NVIS antennas are close to the ground (between 1/10 to 1/5 wavelength above ground) and shoot most of their signals straight up.  Sometimes called "scatter beams" or "cloudwarmers", these antennas can cover a wide area (especially mountainous terrain) with little power.

A NVIS antenna can be configured in several ways, including low-level 1/2 wavelength dipoles or low-level full wave loops.  If your present HF dipole is lower than a quarterwave length, you probably have the beginnings of a simple NVIS antenna without knowing it.  All you would have to add is a halfwave length "reflector" wire on the ground below the main dipole.  Make the reflector element about 5% longer than the main dipole antenna.  This crude arrangement works rather well in putting strong signals into a local or area net.  This is not a DX antenna.  But, for local emergency HF use, this dipole/reflector combination will do the job.

Although I've used such an antenna arrangement in the past, I felt a low-mounted loop would do a bit better in the gain and noise department.  I have an under-the-house 40 meter loop at my present location.  I feed the antenna with 450 ohm ladder line connected to a W9INN 4:1 balun.  The balun is connected to the station rig through a Drake MN-4 antenna transmatch  with a 10 foot/3.04 meters length of RG-8X coaxial cable with UHF connectors.  This antenna does an excellent job on the daily Hawaii Afternoon Net on 7.088 MHz.  The loop is mounted horizontally, approximately 5 ft/1.82 meters above ground.

At my new Puna District home, I've put up several "permanent" antennas to compliment the 80-10 meter flat top dipole (classic doublet) mounted about 50 feet/15.24 meters above ground in two Norfolk Pine Trees.  This past Saturday, while there was a lull in the scattered showers over Hawaii Island, I built a more or less permanent low-mounted 40 meter NVIS loop near the backyard garden. Now that I have more space than before, I'm trying a variety of full-sized antennas, including a "cloudwarmer" to use in emergencies or for general portable use.  The backyard NVIS loop is mounted close to the ground, just like the loop used at my Laupahoehoe qth.  The only difference is that the new loop was built in an open area far removed from power lines and neighbors.

MATERIALS:

Using the general formula 1005/f (MHz)=L(ft) and the resonant frequency of 7.088 MHz (the frequency of the daily Hawaii Afternoon Net), I cut a full wavelength loop measuring 141.79 feet /43.22 meters.  I would configure the loop as a square mounted close to ground level.  Each side would then measure 35.44 ft/10.80 meters.  I used #14 AWG housewire for the antenna.

Four 6 ft/3.04 meters wooden stakes to support the loop.

Four 6 ft/3.04 meters wooden stakes to support the 450 ohm feed running to the 4:1 balun mounted on the garage wall.

A W9INN 4:1 balun.

A Drake MN-4 antenna transmatch.

Ten feet/3.04 meters of RG-8X coaxial cable with UHF connectors to run from the balun to the Drake MN-4 antenna transmatch.  A 3 ft/0.91 meters piece of RG-8X coax connects the transmatch to the station rig (Swan 100-MX or the Ten Tec Argosy II).

Short lengths of RG8X coax to connect the dummy load and low pass filter to the antenna system.

Basic tools, including a soldering station.

Vinyl electrical tape, five ceramic insulators, and nylon ties.

Four short pieces of dacron rope to secure ceramic insulators to the wooden support stakes.

Fifty feet/15.24 meters of 450 ohm ladder line.  This will serve as the antenna feed line.  Used with a 4:1 balun and a sturdy transmatch, the loop will be capable of operating on all amateur radio bands between 40 and 10 meters.

ASSEMBLY:

Four, 6 ft/3.04 meters wooden antenna support stakes were placed at each corner of a square measuring approximately 35.44 ft/10.82 meters on a side.  The loop would be horizontal to the ground, approximately 5 ft/1.82 meter above the lawn.

The tip of each wooden stake had a ceramic insulator attached by a short piece of dacron rope.  The attaching tie off rope measured approximately 2 in/5.08 cm.

The full wavelength loop of antenna wire (141.78 ft/43.22 meters) was threaded through each ceramic insulator.  A fifth ceramic insulator would support the 450 ohm ladder line and its union with each end of the loop.  All connections were soldered and wrapped with several layers of vinyl electrical tape.

Once the feed line was attached to the square loop, I adjusted the tension of the horizontal square loop so that the loop had a uniform height above ground of approximately 5 ft/1.82 meters.

I ran the feed line at a 90 degree angle away from the attachment point to a series of four, 6 ft/1.82 meters wooden stakes, which led to the W9INN 4:1 balun mounted on the garage wall.  The balun was approximately 6 ft/1.82 meters above ground.

A 10 ft/3.04 meters piece of RG-8X coaxial cable with UHF connectors ran through a window patch panel and onto the Drake MN-4 antenna transmatch.  Small patch cords connected my rigs, low pass filter, and dummy load to the transmatch.

INITIAL RESULTS:

As expected, the low-mounted 40 meter loop did an excellent job for local and statewide nets.  Most of my SSB reports ranged from 57 to 59+10 and from 579 to 599+20 for CW contacts.  There was little or no DX worked at the time of testing (early afternoon Hawaii time).  During the evening hours, I was pleasantly surprised by some mainland U.S. contacts on CW, with signal reports ranging from 559 to 579.  My contacts were made with the Swan 100 MX running 20 watts on both SSB and CW.  When I used the Ten Tec Argosy II, I kept power down to 05 watts qrp.  Even at this power, local contacts ranged from 54 to 56 on SSB and from 559 to 599 on CW.

The antenna can be quickly assembled and broken down for portable use.  Best of all, this simple NVIS antenna is inexpensive, easy to build, and requires no ground radial system.  If you want a basic antenna that puts in a strong local or regional signal, try a NVIS antenna in one of its many configurations.  I found the full wavelength loop useful for my purposes.  A low-slung dipole may work better in your location.  Either way, add a NVIS antenna to your collection of amateur radio tools.

REFERENCES:

home.century.net/w9wis/NVIS.html.

http://www.emcomm.org/projects/nvis.htm.

http://dxengineering/com/techarticles/miscinfo/learn-how-to-build-a-nvis-antenna.

http://www.youtube.com/watch?v=aAshymGZ8Ww.

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

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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


Tuesday, November 19, 2013

Simple Ham Radio Antennas: The slanting 80 meter delta loop. Post #243

One of the joys of moving out of my cramped quarters at Laupahoehoe to more spacious property (1 acre) in the Puna District is the ability to erect some decent antennas.  For most of my 36 years as an amateur radio operator, I've had to "make do" with compromise antennas that often performed poorly compared to full-sized antennas.  Thanks to 450 ohm ladder line, a sturdy W9INN 4:1 balun, and a trusty Drake MN-4 antenna transmatch, I've been able to get some excellent multi band contacts with the 40 meter inverted v in the backyard and the 40 meter loop under my post and pier house.  I can't complain.  These antennas have done a good job with my older equipment in the shack.

Once I complete the slow move to my new home in the Orchidland Estates, I won't have to worry about lack of space for antennas and any ground systems I might install.  To date, I erected the following antennas at the new QTH:

A 135 ft/41.15 meters long horizontal dipole (the classic "doublet antenna") with ends supported by two Norfolk Pine trees.  The antenna is approximately 50 feet/15.24 meters above ground.  Fed with 450 ohm ladder line into a 4:1 balun and the Drake MN-4 antenna transmatch, the antenna works on any amateur radio band from 80 to 10 meters.  As a general purpose antenna, the doublet is perfect for my  location.

A 20 meter half square antenna.  This two element vertical doesn't require a ground system.  Two vertical antennas are connected at the top of each mast by a 1/2 wavelength phasing line.  A 50 ohm coaxial cable feed line is attached to the upper left hand corner of the system, with 1/4 wavelength vertical wires running down each fiberglass mast.  The antenna is bi-directional and can add an additional 3 to 4 dB gain over a regular dipole.

A 40 meter inverted v antenna fed with 450-ohm ladder line.  Used with an antenna transmatch and a 4:1 balun, I can get good performance from 40 through 10 meters.  Best of all, I don't need a ground radial system.

A homebrewed 10 meter ground plane vertical cut for 28.4 MHz.  The antenna is attached to the top of a 33-ft/10.06 meter fiberglass mast and fed with 50 ft/15.24 meters of RG-8X coaxial cable with UHF connectors.  I use this antenna for monitoring purposes.  As a single band antenna, it works well.

The temporary 40 meter delta loop fed with ladder line has been taken down to make room for the 80 meter sloping delta loop.

This brings me to the current project.

During my amateur radio "career", I've never had a good antenna for 80 meters.  The 80 meter vertical helix I built several months ago performed better than expected, considering the lack of space for a ground radial system at my Laupahoehoe qth.  I knew I could do better if adequate space were available.

Now that my xyl and I are relocating to our new "homestead", space won't be a problem.  So, this past Saturday and Sunday (16-17 November 2013), I built a simple, inexpensive full size 80 meter loop in the spacious back yard of our property.

MATERIALS:

Most of the materials I had at the new location.  I reused the 33 ft/10.06 meter MFJ telescoping fiberglass mast from the old inverted v and adapted it for the 80 meter delta loop.

I also reused two ceramic insulators, one 5 ft/1.52 meters wooden support stake for the mast, and two 6 ft/1.82 wooden stakes from the old antenna to support and tie off the loop elements.

One "Ladder Lock" connector to attach the 450 ohm ladder line and the delta loop elements.  The connector would be attached at the top of the mast, with the loop running below the apex of the mast.

Fifty feet/15.24 meters of 450 ohm ladder line, one W9INN 4:1 balun, and one Drake MN-4 antenna transmatch.  This system would be used to make the 80 meter delta loop capable of use on all amateur frequencies between 80 and 10 meters.

Short lengths (5 ft/1.82 meters) of dacron rope to tie off the bottom portion of the delta loop.

Short lengths (3 ft/0.91 meters) of RG-8X coaxial cable with UHF connectors to attach station equipment (transceiver, low pass filter, dummy load) to the Drake MN-4 antenna transmatch.

Sufficient wire to build the loop.  Using the general formula 1005/f(MHz)=L(ft) and the design frequency of 3.775 MHz, I cut the loop to a length of 266.22 ft/81.66 meters.  Each side of the delta loop measured 88.74 ft/27.05 meters.  I used #14 AWG housewire bought at Home Depot in Hilo.

ASSEMBLY:

The delta loop was built on the ground.

Once the loop was made, I attached the "Ladder Lock" connector with the 450 ohm ladder line attached  to the tip of the mast.

Because of the low height of the loop (the mast was only 33 ft/10.06 meters tall), I decided to make the antenna into a sloping delta loop, a design I had used with the 40 meter delta loop.

I then hoisted the mast onto its support stake, ran the loop at a 45 degree angle from the mast , and attatched the bottom of the loop to its wooden support stakes.  I adjusted the shape of the loop so it resembled a sloping delta.  The antenna is very close to the ground.

I ran the 450 ohm ladder line from the apex of the mast to the W9INN 4:1 balun attached to the garage wall.

Twenty five feet/7.62 meters of RG-8X coaxial cable with UHF connectors ran from the balun to the Drake MN-4 antenna transmatch in the radio room (in the corner of the garage).

To minimize rf in the shack, I attached a counterpoise measuring 66 feet/20.12 meters to the ground lug of the Drake MN-4 transmatch.

INITIAL RESULTS:

With the help of the trusty Drake MN-4, I've kept the SWR below 1.3 to 1 on all amateur bands from 80 through 10 meters.  Obviously, some antenna trimming will be done in the future.  But for now, I have no complaints about the loop's performance.  Depending on the band of choice and propagation, I've received ssb reports varying from 57 to 59+10 and cw reports ranging between 569 to 599 +10.  During the short testing period, I was running between 20 and 50 watts from my old Swan 100 MX.

So far, I'm satisfied with the performance of this slanting 80 meter delta loop.  This was a fun project.  Other than buying some extra antenna wire, I had all of the ingredients for this antenna in my garage.  Sometimes, being a "packrat" pays off.

REFERENCES:

Noll, Edward M. (W3FQJ).  73 Vertical, Beam, and Triangle Antennas. Editors and Engineers.  Indianapolis, Indiana, 46268.  First Edition, 1979.  pp.126-127.

Orr, William I. (W6SAI). and Cowan, Stuart D. (W2LX).  The Radio Amateur Antenna Handbook.  Radio Publications, Inc.  Wilton, CT, 06897.  First Edition, 1978. pp.113-128.

DeMaw, Doug. (W1FB).  Novice Antenna Notebook.  American Radio Relay League, Newington, CT, 06111. First Edition, 1988.  pp.78-90.

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.


Thursday, November 14, 2013

An Emergency "Go Kit" for the home station. Post #242

A few days ago I described the simple emergency "go kit" installed in my Honda Odyssey van.  This simple station has served me well for both portable and Field Day use.  I have no doubt the system will work during emergencies.  In fact, I've set up my "go kit" station in the backyard with excellent results using a  simple inverted v antenna and an under-the-house 40 meter loop on my lot.

Although this arrangement worked very well, I wanted to make a special "standby" station in case my main station didn't work for some reason.  Fortunately, I had a few spare rigs in the shack, and I decided to employ them in my home emergency station.

My main amateur radio station has the following equipment (most of it old, but totally functional):

One Ten Tec Argosy II transceiver and Ten Tec power supply.  I can run this rig off the electrical mains or with a solar panel/deep cycle marine battery combination.

One Drake MN-4 antenna transmatch.  I can use 450 ohm ladder line as a feed line once I attach a W9INN 4:1 balun.

Several 50-foot/15.24 meters lengths of RG-8X coaxial cable with UHF connectors.

Several RG-8X coaxial cable patch cords with UHF connectors.  These short (3 feet/0.91 meters) cables are used to connect equipment to the transmatch, low pass filter, and dummy load.

Ten Tec microphone and J-38 key.  I'm old school and I prefer the old J-38 key for my slow speed rag chews on 40 meters.

Assorted tools, radio log, note paper, HP Pavilion Slimline PC, landline telephone, and cell phone.

Much of this equipment will be integrated into my home emergency station.

THE BACKUP STATION;

I had two options.  First, I could just use the proven portable station installed in my van.  I've done this on occaison with good results.

Second, I could use some of my older equipment that is stored in the garage.  With continuous use, the equipment would be less prone to deterioration in Hawaii's tropical climate.

I elected to build a backup station with the extra equipment I had in the garage.  I'm one of those hams that rarely throws anything away, so I had plenty of choices for antennas, rigs, and power.

My rig selection narrowed down to my venerable, but dependable Swan 100 MX (early solid state rig) and the reliable Kenwood TS-520 (a hybrid rig with 2 6146B finals).  I decided to keep both rigs on a table next to the main station.  Both stations would be within easy reach in my large garage.

Although both classic rigs have their own power supplies, I've elected to use a solar panel/deep cycle marine battery combination to provide power to the backup rigs.  Fortunately, a 12 volt adaptor came with the old Kenwood.  I also have an old inverter to convert the battery power to 110 volt AC if I have to.  In most non-emergency cases, I power the TS-520 with its own power supply.  The Swan 100 MX usually runs on battery power.  I run both rigs at 50 watts or less to conserve power.  This power level appears adequate for my use.

My backup microphones include a Shure 444 for the Swan and the standard microphone that came with the Kenwood TS-520.  For CW purposes, I have another J-38 key.

With some modifications, I can use the home station's 40 meter inverted v and the under-the-house 40 meter loop for antennas.  I just replace the RG-8X feed lines with either 50 feet/15.24 meters of 450 ohm ladder line for the inverted v or 25 feet/7.62 meters of 450 ohm ladder line for the under-the-house loop.  I use a W9INN 4:1 balun with the Drake MN-4 antenna transmatch to create a decent match for the antenna.  If the Drake MN-4 develops problems, I have an old MFJ-941E Versa Tuner to take its place.

The antenna measurements remain the same.  Both antennas use #14 AWG housewire for the antenna elements.  For the inverted v, I use the general formula 468/f(MHz)=L(ft).  For the loop antenna, I use the general formula 1005/f(MHz)=L(ft).  I designed both antennas to be resonant on 7.088 MHz ( the frequency of the Hawaii Afternoon Net).  The loop was cut to a length of 141.78 feet/43.22 meters, while the inverted v dipole was cut to a length of 66.02 feet/20.13 meters.  The dipole was cut into two equal pieces, measuring 33.01 feet/10.06 meters.

Once the antennas were restrung and hoisted into position, I tested them with my new backup station.  Thanks to the ladder line, the 4:1 balun, and the Drake MN-4 transmatch, I was able to keep SWR below 1.3 to 1 on the 40, 20, 15, and 10 meter bands.  The inverted v proved to be a good DX antenna during the early evening and early morning hours.  The low level loop was usable on the 40, 20, 15, and 10 meter bands.  However, this loop was not intended to be a DX antenna.  For all practical purposes, this low-level antenna served as a NVIS (near vertical incident skywave) antenna, giving excellent, local coverage out to 300 miles/480 km--perfect for statewide coverage.

During an emergency, I would most likely be using the low-level loop to check into local emergency nets in Hawaii.  For that purpose, the loop does an excellent job.

I hope my experience in building an emergency "Go Kit" for your station has proved helpful.  Experiment with what you have.  Be creative.  Get your materials locally at the nearest hardware store or home improvement outlet.  Build your backup station now.  You never know when some emergency will force you to operate in less than optimum conditions.

REFERENCES:

Check out antenna projects in the recent edition of the ARRL Antenna Book.  This resource is full of simple, effective antenna ideas.

http://www.emergencyradiokit.com.

http://arrl.org/forum/topics/view/870.

http://www.youtube.com/watch?v=_BrHsMfEZT4.

http://www.orgsites.com/oh/soaraares/_pgg5.php3.

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

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Tuesday, November 12, 2013

A simple "Go Kit" for emergencies. Post #241

In light of the recent natural disaster in the Philippines (super Typhoon Haiyan), it might be useful to review just how prepared we amateur radio operators are for natural and man-made disasters.  Many of the hams running emergency traffic in the Philippines are using low powered rigs and simple antennas to maintain a communications lifeline in devastated areas of the Central Philippines.  Perhaps, we should do the same.

In my 36 years as an amateur radio operator, I've always followed the policy of having spare equipment, antennas, parts, tools, and standby power should an emergency arise.  While those of us living in Hawaii aren't prone to the series of disasters befalling southeast Asia, we do get our share of hurricanes, severe thunderstorms, earthquakes, and, occasionally, tsunamis.  Most hams living in the 50th state are prepared to provide emergency communications should the need arise.

It's prudent to have an emergency radio system installed in your home as well as in your vehicle if you are cut off from your family and job.

With the story of Typhoon Haiyan still etched in my mind, I began an inventory of my station to determine what was available for emergency use.  In other words, I wanted to make sure I had a "go kit".  A "go kit" is a portable amateur radio station which the amateur can use when he/she is asked to lend support for an event or emergency.

I first concentrated on a "go kit" for my personal vehicle--a 2010 Honda Odyssey Van.  My home "kit" would be assembled later.

A quick check of the van showed I had already assembled a basic portable station which could be used in an emergency.  I often travel to a state or county park near my Laupahoehoe home and operate portable for a few hours with some simple equipment and basic antennas.

Here's what I found:

One MFJ telescoping fiberglass mast that could be extended to 33 feet/10.06 meters.  I've used this inexpensive mast to support sloping dipoles and inverted vee antennas.

Pre-made dipole antennas for 40, 20, 15, and 10 meters.  I used the general formula 468/f (MHz)=L (ft) for each antenna.  In my situation, my 40 meter dipole was cut for a resonant frequency of 7.088 MHz (the frequency of the Hawaii Afternoon Net).  The length of this dipole was 33.1 feet/10.06 meters for each dipole element.  The 20 meter dipole was cut for a resonant frequency of 14.200 MHz.  The length of this dipole was 16.475 feet/5.022 meters for each dipole element.  The 15 meter dipole was cut for a resonant frequency of 21.250 MHz.  The length of each dipole element was 11.01 feet/3.35 meters.  The 10 meter dipole was cut to a resonant frequency of 28.400 MHz.  The length of each dipole element was 8.23 feet/2.51 meters.  Each dipole antenna was attached to a Budwig Hi-Que coaxial center connector (available through Fair Radio Sales, Lima, Ohio).  The end of each antenna was attached to a ceramic insulator which could be tied off at a wooden stake.

Two 50-foot/15.24 meters lengths of RG-8X coaxial cable with UHF connectors.  These cables would be my feed line.

Three 5-foot/1.52 meters wooden stakes.  One stake would support the fiberglass mast.  The other two stakes would be tie off points for the inverted vee antenna.

One solar charged (pv panels) deep cycle marine battery.

A Yaesu FT-7 QRP transceiver with microphone and cw key (J-38).  This old, low powered rig has served me well for many years.

A Kenwood 2500 series 2 meter HT with extra battery.  This is an old HT, but it works very well on the local repeater system.  I'm in the process of buying a more modern HT with better capabilities.

An old 4-channel Bearcat public service scanner with extra AAA batteries.  This handheld relic from the 1980s still works.  I have crystals installed for police and fire dispatch, as well as Medivac, and NOAA weather.

An old Radio Shack TRC 23 channel CB transceiver with magnetic mount roof antenna.  CB is still used on Hawaii Island.  Many community centers, which serve as Red Cross Shelters, have CB installations.  CB still serves a useful purpose on this largely rural island.

A three-day supply of dried food, water, clothing, and toiletries.

All of this equipment is contained in three large plastic storage bins and placed in the cargo area of the van.

For all practical purposes, my "go kit" is already made.  All I will add are some more batteries for the HT and scanner, a small table, a collapsible chair, and a small antenna transmatch.  The system has been tested and it works.

Next, I'll start on a backup system for my home station.

REFERENCES:

http://www.emergencyradiokit.com.

http://www.arrl.org/forum/topics/view/870.

http://www.youtube.com/watch?tv=_BrHsMfEZT4.

http://www.orgsites.com/oh/soaraares/_pgg5.php3.

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

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Sunday, November 10, 2013

Super Typhoon devastates the Central Philippines. Post #240

Today, our prayers are with the residents of the Central Philippine Islands, who are just starting to recover from the devastation of super typhoon "Haiyan."  According to Ramon Anquitan (DU1UGZ) of the Philippine Amateur Radio Association, amateur radio operators in that island nation are providing emergency communications links to the government, as well as handling health and welfare traffic from impacted areas, such as Tacloban City--one of the hardest hit areas southwest of Manila.

Although the Philippine Red Cross says there are at least 1,000 dead from the devastating storm, reports from the Associated Press and Radio Australia put the dead and missing total somewhere near 10,000.

Typhoon "Haiyan" was an especially strong storm system with winds exceeding 175 mph (280.5 km/hr) in some areas.  Storm surge, heavy rain, and flooded rivers have destroyed thousands of homes and damaged hundreds of businesses in the Cebu area.  Government officials have sent  relief workers to the area, with amateur radio operators providing needed communications links.  Ramon Anquitan (DU1GDZ) says emergency traffic is being sent on a HF frequency of 7.065 MHz, on some 2 meter repeaters and simplex, and through surviving parts of the internet.  Ramon is asking fellow amateurs to stay off 7.065 MHz unless you are relaying health and welfare traffic into or out of the Philippines.

If you wish to aid survivors of this catastrophic storm, please contact your chapter of the American Red Cross.  You can make out your checks to "Typhoon Haiyan Relief."

I'm proud of my fellow amateur radio operators in the Philippines, who are maintaining communications links under very difficult conditions.

REFERENCES:

http://www.southgatearc.com.
Radio Australia
"The Honolulu Star-Advertiser", 10 November 2013.
The "Hawaii Tribune-Herald", 09 and 10 November 2013.
Ramon Anquilan (DU1UGZ), Philippine Amateur Radio Association, 09-10 November 2013.

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

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Tuesday, November 5, 2013

My favorite Amateur Radio antenna books. Post #239

If you've been an amateur radio operator for any length of time, you probably have a good collection of parts, books, magazine articles, wire, coaxial cable, connectors, and basic tools to support your hobby.  This "junk box" is part of our amateur radio tradition...making do with what you have on hand.  I'm no exception.  In my 36 years as a licensed amateur radio operator, I've accumulated a wide collection of items, ranging from books to spare rigs.  Of course, the collection circulates a bit through trades, upgrades, giveaways to newly licensed hams, and, finally, to the recycling station.

One of the things I rarely sell or giveaway is my growing collection of books related to Amateur Radio and Amateur Radio antennas.  Many of these volumes were bought when I was newly licensed or successfully upgraded my license.  Nowadays, the task of assembling an Amateur Radio library is easier, thanks to the internet, Amateur Radio-related websites, and the outstanding archive of technical information available to ARRL (American Radio Relay League) members.  Nonetheless, I still collect books about radios and antennas.  This tendency must have been acquired when I was once a librarian at the University of Hawaii at Hilo Library.  But, that's a strange tale best told at another time.

As mentioned previously, my xyl and I are moving our household to a larger rural property in the Puna District of Hawaii Island.  As part of that process, I've been going through my "junk box" and sorting out the items I wish to transfer to our permanent home.  The items worthy of retaining include my old rigs (Swan 100 MX, Kenwood TS-520, Yaesu FT-7, and the Ten Tec Argosy II).  My antenna transmatches (Drake MN-4 and the MFJ 941-E Versa Tuner), the slightly used Elecraft K3, and my collection of wire, coax, and connectors are also coming with me.  My antenna book collection was the last category to be inventoried.  I'm still in the process of sorting that collection into the "keep" and "no keep" category.  Over the next few weeks, I'll make a complete list of the antenna reference materials that will make the "cut".

So far, these volumes have been retained, many for sentimental reasons:

A current edition of the ARRL Handbook and ARRL Antenna Handbook.  Both of these works are basic reference materials that every Amateur Radio operator should have.

"The Radio Amateur Antenna Handbook" by William I. Orr (W6SAI) and Stuart D. Cowan (W2LX).  This book provides many simple, practical, and inexpensive antenna ideas using locally available materials.

"73 Vertical, Beam, and Triangle Antennas" by Edward M. Noll (W3FQJ).  A basic book for antenna experimenters.  All you need to make Ed's simple antennas are a telescoping mast, some aluminum tubing, ingenuity, and a desire to explore antenna design.

"Novice Antenna Notebook" by Doug DeMaw (W1FB).  A concise introduction to antenna theory, construction, and maintenance of simple wire antennas.  I've tried most of Doug's ideas with great results.

As I continue my packing routine, I'll list some more of my favorite antenna books.  Building antennas and simple kits are a good way to expand your knowledge of Amateur Radio.  Besides, all of this "hands on" experience is fun.

REFERENCES:

The ARRL Handbook and ARRL Antenna Handbook are available from the ARRL, 225 Main St., Newington, CT, 06111.

These books may be out of print.  They occasionally turn up on e-bay:

DeMaw, Doug (W1FB).  Novice Antenna Notebook.  ARRL, Newington, CT, 06111.  First Edition, Copyright 1988.

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

Orr, William I. (W6SAI) and Cowan, Stuart D. (W2LX).  The Radio Amateur Antenna Handbook.  Radio Publications, Inc. Box 149, Wilton, CT., 06897.  First Edition, 1978.

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

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Thursday, October 31, 2013

A 40-10 Meter sloping Delta Loop Antenna. Post #238.

A one-wavelength loop is one of my favorite antennas.  Loops may be built in a square, circular, rectangular, of triangular form to create an effective, inexpensive antenna.  Loops can be built for single band service using coaxial cable and a quarter wave transformer or for multiple band use employing 450 ohm ladder line fed into a 4:1 balun and then into an antenna transmatch.  A small length of 50 ohm coaxial cable with UHF fittings can be used to connect your transceiver to the transmatch.

For my growing antenna farm at my new homesite in the Puna District of Hawaii Island, I needed an antenna which would give me good local coverage for local state wide nets and a decent signal for DX work.  From my location on Hawaii Island, almost anything beyond Hawaii counts as DX.  I elected to build a simple, one wavelength long sloping delta loop supported by a telescoping fiberglass mast and supported at the bottom ends by two wooden stakes.

In order to cover 40 through 10 meters, I designed the delta loop for the lowest frequency of use.  In this case, that frequency was 7.088 MHz, the meeting place of the daily Hawaii Afternoon Net.  I would operate the loop on its various harmonics with 450 ohm ladder line, a W9INN 4:1 balun, a short length of 50 ohm coaxial cable, and my trusty Drake MN-4 transmatch.  I would use my MFJ 941-E Versa Tuner and my Argosy II transceiver for 30 meter contacts.  For the remaining bands, I could use either the Argosy II or the old Swan 100 MX.

MATERIALS:

One 33-foot (10.06 meters) MFJ telescoping fiberglass mast.  The mast would support the apex of the delta loop.

Three ceramic insulators--one at the apex of the loop and the other two at the bottom two ends of the loop.

#14 AWG housewire.  This is sturdy material and will stand up to the tropical heat and rain.   You could also use whatever wire you have in the shack.  I've found #18 speaker wire from Radio Shack a good alternative wire source.  Using the general formula 1005/f(MHz)=L(feet) and my preferred frequency of 7.088 MHz, the total length of the loop came out to be 141.78 feet/43.22 meters.  Each side of the delta loop would be 47.26 feet/14.40 meters.

Fifty feet/15.24 meters of 450 ohm ladder line. This would be the feed line for the antenna.

One W9INN 4:1 balun.

A sturdy transmatch.  I had a Drake MN-4 and a MFJ 941-E Versa Tuner at my disposal.

One 5-foot/1.52 meters wooden support stake for the fiberglass mast.

Two 6-foot/1.82 meter wooden stakes to support the bottom of the delta loop.

Short pieces of Dacron rope to tie off the bottom loop element to its stakes and to attach the upper portion of the loop to the top of the mast.

Basic tools, including a soldering gun, vinyl electrical tape, pliers, and nylon ties.

ASSEMBLY:

The delta loop was built on the ground.

I laid out the antenna wire on the lawn in back of my garage, with each side measuring 47.26 feet/14.40 meters.  The wire was threaded through 3 ceramic insulators.  At the lower right hand corner of the loop, attached the 450 ohm ladder line.  All connections were soldered and covered with several layers of vinyl electrical tape.

I attached the top of the delta loop to the tip of the mast.  The ceramic insulator was secured by nylon ties and vinyl electrical tape. 

I hoisted the mast onto its support stake, pulled the loop away from the mast at about a 45- degree angle, and secured the bottom of the loop to two 6-foot/1.82 meter wood stakes. Short pieces of Dacron rope attached the ceramic insulators to the wooden end stakes.  Some minor adjustments were made so that the delta loop assumed a uniform shape as it came away from the fiberglass mast.

The 450 ohm ladder line ran from the right hand bottom insulator to the W9INN 4:1 balun on the garage wall.  The balun was about 5 feet/1.52 meters) above ground.  At no time was the ladder line allowed to touch the ground.

A twenty-five-foot/7.62 meters length of RG-8X coaxial cable with UHF fittings was attached to the balun. The coaxial cable was run into the shack through a homemade patch panel in the shack window.  The cable was connected to the Drake MN-4 antenna transmatch.  From the transmatch a series of 3-foot/0.91 meter coaxial patch cords connected the transceiver, dummy load, and low-pass filter to the Drake MN-4.  I also added a 33-foot/10.06 meter "counterpoise" wire to the ground lug of the Drake MN-4 transmatch.

INITIAL RESULTS:

With the help of the Drake MN-4 transmatch and the MFJ 941-E Versa Tuner, I was able to get a 1:1 SWR reading on all amateur radio frequencies from 40 through 10 meters.  Daytime coverage on 40 meters is excellent with 57 to 59 reports on ssb and 579 to 599+ on cw.  Despite the loop's proximity to ground, I've been able to get some excellent DX on 20 and 15 meters.  Ten meters has ranged from good to poor, depending on the time of day and propagation.  Most of my DX work on 20 and 15 meters has ranged from 56 to 59 on ssb and 569 to 599 on cw.  I ran the Swan 100 MX at 50 watts and the Ten Tec Argosy II at approximately 20 to 25 watts.

The sloping delta loop is a simple, inexpensive antenna that will deliver good results for both local and DX contacts.  Unlike my vertical antennas, I didn't need a ground radial system to get decent performance.  Wire antennas are fun to build.

REFERENCES:

http://www.k5rcd.org/hor%20loop%20instruct.htm.
http://www.youtube.com/watch?v=WF1Tlfbl8Xo.
DeMaw, Doug (W1FB).  Novice Antenna Notebook.  ARRL, Newington, CT., 06111.  First Edition, 1988.  pp 78-89.
Noll, Edward M. ( W3FQJ).  73 Vertical, Beam, and Triangle Antennas.  Editors and Engineers, Ltd.  New Augusta, Indiana.  Seventh Printing, 1979.  pp 126-138.

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.

 

Sunday, October 27, 2013

A Multi-Band horizontal dipole. Post #237

How would you like to build a simple, inexpensive multiband antenna that will give you hours of enjoyment chasing DX or "ragchewing" with your local amateur radio friends?  Sometimes, when it comes to "homebrew" antennas, you can't beat a 40 through 10 meter dipole or doublet fed  by ladder line into a suitable antenna transmatch.  One antenna can perform well on a variety of amateur radio bands if it is designed and built carefully.

Ideally, we could all use a 50-foot (15.24 meter) tower with a 4-element monobander on 20 meters, plus separate antennas for 160, 80, 40, 15, 10, and whatever other bands you can squeeze in.  However, most of the amateur radio operators I know can manage only one or perhaps two HF antennas on their small properties.  Add to this mix the growing trend of antenna restrictions found in many housing areas these days and you've got the one antenna scenario.  And that antenna must be hidden in many cases.

Enter the horizontal flat top half wavelength dipole and its immediate cousins the inverted vee, the sloping dipole, and the vertical dipole.  In past posts, I've described the inverted vees and sloping dipoles used at my station.  All of these antennas have performed well as multiband antennas using 450-ohm ladder line, a 4:1 balun, and a sturdy antenna transmatch.  My two antenna "tuners" are the trusty Drake MN-4 and a very old MFJ 941-E Versa Tuner which I use for 30 meters.

So, let's build a simple dipole half wavelength antenna and get ourselves on the air.

According to the late William Orr (W6SAI), the common half wavelength dipole fed at the center with two conductor feed line is an "inexpensive antenna to build and to get working."  If you use 450-ohm ladder line or television 300-ohm twin lead in combination with a 4:1 balun and robust antenna "tuner", you'll have a working multiband antenna at minimum cost.

MATERIALS:

If you're going to use the dipole for several bands, design your antenna for the frequency of the lowest band.  In my case, I wanted to work 40 through 10 meters.  So, using the frequency of 7.088 MHz (the frequency of the daily Hawaii Afternoon Net) and the general formula 468/f (MHz)=L (ft), I computed a half wavelength of 66.02 feet(20.13 meters).  Each dipole element would be half that amount or 33.01 feet (10.06 meters).
Some antenna experts recommend that you cut your antenna elements a bit long to allow for trimming and SWR adjustments.  For my purposes, I left each element slightly longer than 33-feet (10.06 meters).  The antenna transmatch would compensate for the mismatch found on each band.

Two masts to support the dipole.  I had two spare MFJ 33-foot (10.06 meters) telescoping fiberglass masts in the garage of my new home site in the Puna District.

Two ceramic insulators to tie off the antenna elements to the supporting masts.

Two 5-foot (1.52 meters) wooden stakes to support each mast.

One "homebrew" center connector to support each conductor of the 450-ohm feed line.  I used some plastic cut from an old "Clorox" (household cleaner) bottle for the center connector.

Two pieces of #14 AWG household wire, measuring slightly more than 33 feet (10.06 meters) each.  These wires would be the flat top horizontal half wavelength dipole.

Fifty feet (15.24 meters) of 450-ohm ladder line to feed the antenna.

One W9INN 4:1 balun.

Twenty five feet (7.62 meters) of RG-8X coaxial cable with UHF connectors.  The ladder line would be connected to the 4:1 balun and then the coax would be connected to the balun.  The coax would run into the shack for eventual connection to my transceiver, an old but trusty Ten Tec Argosy II.  If I wanted to operate on 30 meters, I would swap out the Drake MN-4 for the MFJ 941-E Versa Tuner.

Short pieces of dacron rope to attach the ceramic insulators to each mast.

Several 3-foot (0.91 meters) RG-8X coax patch cords to connect the Argosy II to the Drake MN-4/Versa Tuner, the dummy load, and the low pass filter.

Basic tools, soldering gun, tape, nylon ties.

ASSEMBLY:

The dipole was built on the ground.  I measured out the antenna elements, attached the ceramic insulators to the end of each element, and secured each end insulator to its respective mast with dacron rope.  The rope was further secured to each mast with several nylon ties.

The 450-ohm ladder line was secured to a "homebrew" plastic center connector with nylon ties.  Each antenna segment was soldered to a conductor of the ladder line.  Those connections were wrapped with several layers of vinyl electrical tape.

Each mast was hoisted on its wooden support stake and adjusted so that there was a slight "dip" in the horizontal flat top dipole towards the center conductor.

The ladder line was led to a W9INN 4:1 balun attached to the garage wall.  The balun was approximately 10 feet (3.04 metes) above ground level.  A 25-foot (7.62 meters) length of RG-8X with UHF connectors was attached to the 4:1 balun and fed to the radio room through a "homebrew" patch panel in the room window.

The coax was attached to the Drake MN-4 transmatch.  Short pieces of coax cable connected the Argosy II, the dummy load, and the low pass filter to the transmatch.  I also added a 33-foot (10.06 meters) "counterpoise" wire to the ground lug of the Drake MN-4.  So far, there have been no rf problems in the shack.

INITIAL RESULTS:

For a general antenna covering several bands, performance has been quite acceptable.  Although I would have preferred to have the dipole at a higher elevation, I couldn't find suitable trees nearby that would accommodate a height of a half wavelength above ground for 40 meters--66 feet (20.12 meters).  Even at this lower elevation, the antenna works well.  Performance on 20, 15, and 10 meters is good.

With the help of the Drake MN-4 transmatch and the MFJ 941-E Versa Tuner, I can get a SWR of 1.1 to 1 across each band.  Most of my mainland U.S. contacts range from 559 to 599 (cw) and from 54 to 59+(ssb), depending on the band and time of day.  Local Hawaii contacts often exceed 599 (cw) and 59 (ssb).
I usually run the old Argosy II at 20 to 30 watts.  The power supply is a solar panel/deep cycle marine battery combination.

Most of my materials were bought locally or were found at garage sales (#14 AWG wire, ceramic insulators, dacron rope).

Of course, your results will vary.  Soil conditions, available space, and property restrictions will affect your design.  But, for a simple, inexpensive antenna that delivers both excellent local contacts and sometimes decent DX, you can't beat the old half wavelength dipole. Besides, unlike a vertical antenna, you don't need a ground radial system to make the dipole work.  And you get the satisfaction of making the antenna yourself.

REFERENCES:

Orr, William I. (W6SAI) and Cowan, Stuart D. (W2LX).  The Radio Amateur Handbook.  Radio Publications, Inc., Wilton, CT, 06897.  First Printing 1978.  pp. 130-137.

http://www.ehow.com/how_4530_build-dipole-antenna.html.

http://voics.yahoo.com/how-dipole-antenna-340817.html.

http://www.buzzle.com/articles/dipole-antennas-build-a-dipole.

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

http://www.stepbystep.com/how-to-build-a-dipole-antenna-54624.

Or, you can consult the latest edition of the ARRL Antenna Book.

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.