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.







Tuesday, October 22, 2013

A 30 Meter Sloping Dipole Antenna. Post #236

The 30 Meter Amateur Radio band (10.100 MHz to 10.150 MHz) is territory for the cw and digital enthusiast.  You can find cw operators around 10.105 MHz and many Japanese hams clustering around 10.130 MHz.  In between, you'll find RTTY, PSK 31, FAX, and other digital modes.  If you're a cw operator, 30 Meters can be the place to make new friendships at a leisurely pace while increasing your sending and receiving skills.

Antennas for this tiny sliver of the rf spectrum are modest and inexpensive to build with many materials obtainable from the nearest home improvement outlet or hardware store.

Over the past few weeks, I've built several 30 Meter antennas for my new house lot in the Puna District, including an inverted vee, a ground plane, a delta loop, and even an inverted "L".  All have worked well.

The latest addition to my growing antenna farm is a 30 Meter halfwavelength sloping dipole.  This variation of the basic horizontal, halfwavelength flat top dipole has proven to be a simple, effective antenna suitable for both home and portable use.

MATERIALS:

One 33-foot/10.06 meters MFJ telescoping fiberglass mast.  I disconnected my 30 Meter inverted vee and used those elements to form the sloping dipole.  The top of the sloping dipole would be attached to the tip of the mast, with the bottom portion being run off at an approximately 45 degree angle to a nearby wooden support stake.

Two ceramic insulators, one for each element of the sloping dipole.

Based on the general formula 468/f(MHz)=L(feet) with a chosen frequency of 10.125 MHz (mid-band), the total length of the sloping dipole worked out to be 46.22 feet/14.09 meters.  Each element of the dipole would be cut to a length of 23.11 feet/7.04 meters.  You may want to cut the wires a little longer to adjust for tuning purposes.  I chose #14 AWG housewire for the antenna elements.

One Budwig HQ-1 center coaxial connector.  I happened to have a spare connector in the junk box.  You could also make a center connector from pvc pipe, plexiglass, or some other sturdy material.

Fifty feet/15.24 meters of RG-8X coaxial cable with UHF connectors.  This would be the antenna feed line.  If you want to run more than a few hundred watts with this antenna, I would recommend a sturdier coax, such as RG-8 or RG-213.

Two 5-foot/1.52 meters wooden stakes.  One stake will support the fiberglass mast.  The other would be used to tie off the bottom end of the sloping dipole.

Basic tools, such as wire cutters, plastic vinyl tape, nylon ties, and soldering equipment.

A transceiver capable of using the 30 Meter amateur radio band.  I used an old, reliable Ten Tec Argosy II for this task.

An antenna transmatch to handle the small amount of SWR in the antenna system.  I had an old MFJ 941-E Versa Tuner for the "tuning" process.

Various coaxial patch cords to connect the transmatch to the transceiver, dummy load, and low pass filter.

A key capable of sending Morse Code.  I elected to use an old J-38 manual key from my days as a novice operator.

ASSEMBLY:

The antenna was built on the ground and later hoisted into position.

I attached the top dipole element to the + terminal of the Budwig coax connector.  I attached the bottom part of the sloping dipole to the - terminal of the Budwig coax connector.  Both connections were soldered and covered with several layers of vinyl electrical tape.

A ceramic insulator was attached to the end of the top element.  The insulator was secured to the tip of the mast with vinyl electrical tape and nylon ties.  A ceramic insulator was also attached to the end of the bottom antenna element.

Before I attached the RG-8X to the Budwig center connector, I wound 8 turns of the coax into a "choke balun" approximately 8 inches/20.32 cm in diameter.  Hopefully, the balun would keep rf off the feed line and out of the shack.

I then hoisted the fiberglass mast onto its wooden support stake.  I led the sloping dipole away from the mast at an approximate angle of 45 degrees.  The lower antenna element was tied off at the wooden stake.  The slope of the dipole was directed to the U.S. mainland (northeast from my location).  I really didn't expect much directivity from the sloping dipole, but the direction was convenient from an aesthetic point of view.  The antenna would slope into my back yard and be unnoticeable from the street.

I ran the coax feed line through a homemade patch panel in the shack window and attached it to the MFJ Versa Tuner.  I also attached a 23.11-foot/7.04 meter "counterpoise" wire to the ground lug of the "tuner."

INITIAL RESULTS:

Thanks to the MFJ 941-E Versa Tuner, I was able to keep the SWR 1.1 to 1 across the entire band.  Obviously, some trimming of the antenna will be necessary, but, for now, I'm satisfied with the performance of this temporary arrangement.  In my location, 30 meters works very well from the late afternoon through late evening.  Reports ranged from 559 to 599 with the Argosy II running about 25 watts.

Thirty meters is a fun place to be.  You can get a lot of contacts with modest equipment and an inexpensive wire antenna built at home.

REFERENCES:

http://www.chem.hawaii.edu/uham/antennas.html.
http://www.arrl.org/files/Technology/tis/info/pdf/9106023.pdf.
http://youtube.com/watch?v=mgEibY3INHo.
http://www.hamuniverse.com/n4jaantennabook.html.
w4rnl.net46/sloper.html.

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.


Saturday, October 19, 2013

A modified 30 Meter Ground Plane Antenna. Post #235.

This week, I'm exploring the joys of 30 meters and the antennas that support this intriguing amateur radio band.

Last week, I built a simple 30 meter inverted vee antenna which continues to deliver outstanding performance.

Today, I decided to try a 30 meter ground plane antenna, consisting of a main vertical element and four sloping radials.  Many antenna experts believe that sloping the radial elements by 45 degrees will produce a better match for 50 ohm coaxial cable feed lines. Although my sloping radials don't come off the connector at 45 degrees,  they do seem to produce a usable match for my RG-8X feedline.  Any mismatch is corrected by my standby antenna transmatch--an old MFJ-941 E Versa Tuner.

According to "searchmobilecomputing.tectarget.com", a ground plane "is a variant of the dipole antenna designed for use with an unbalanced feed line such as coaxial cable.  It resembles a coaxial antenna whose lower section consists of straight elements called radials instead of a hollow cylinder.  There are two or more radials, each measuring 1/4 wavelength.  The radials are connected to the outer conductor or shield of the feed line.  The main element is connected to the center conductor."

My homebrewed ground plane is designed for the narrow range of frequencies between 10.100 MHz and 10.150 MHz.  The antenna was made to be resonant at 10.125 MHz--the midpoint of the band.

MATERIALS:

One 33-foot/10.06 meters MFJ telescoping fiberglass mast.  I had a spare mast in the garage at my new home site in the Puna District.

One Budwig HQ-1 coaxial center connector.

Five, 5-foot/1.52 meter wooden support stakes.  One stake would serve as the mast support, while the other stakes would support the drooping radials (ground plane).

Five ceramic insulators--one would support the top of the vertical element at the tip of the mast.  The other four would be used to tie off the drooping radials to their wooden support stakes.

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

A sufficient amount of #14 AWG housewire to make one vertical element and four radial segments.

Several 3-foot/0.91 meters RG-8X coaxial cable patch cords to connect the transceiver to the antenna transmatch, low pass filter, and dummy load.

A 30 meter capable transceiver.  In this case, I used an old Ten Tec Argosy II transceiver.

One MFJ 941-E Versa Tuner.  The "tuner" would handle any mismatch in the antenna system.

Basic tools, including wire cutters, soldering station, nylon ties, and vinyl electrical tape.

ASSEMBLY:

The antenna was built on the ground and later hoisted into position.

Using the general formula 234/f(MHz)=L, each radial and the main vertical element were cut to 23.11 feet/7.04 meters.  Some antenna experts recommend that radials be cut about 5% longer than the vertical element.  I decided to keep each antenna element the same length.

I attached and soldered the vertical element to the + terminal of the Budwig HQ-1 center connector.  The connection was covered with a layer of vinyl electrical tape.  I attached a ceramic insultor to the top end of the vertical element.  The vertical element was secured to the fiberglass mast with nylon ties.  The top insulator was taped to the top of the mast and secured with nylon ties.  The Budwig connector was oriented so that the + terminal faced up and the - terminal (with the radials) faced down.

Four radial elements were connected to the - terminal of the Budwig HQ-1 center connector.  The connections were soldered and taped with a layer of vinyl electrical tape.  Ceramic insulators were attached to the end of each radial.

I hoisted the mast on top of its wooden support stake.  The bottom of the vertical element was about 10 feet/3.04 meters above ground.  The radials were carefully spaced out and led away from the mast.  The radials were then attached to 4 wooden posts.  The wooden posts and the drooping radials were positioned to face North, South, East, and West (0, 90, 180, and 270 degrees).

The RG-8X feed line was led away from the fiberglass mast at a 90 degree angle, with the coax being approximately 10 feet/3.04 meters above ground.

The feed line entered the shack through a small hole in the radio room window and then to the MFJ 941-E Versa Tuner.  I also ran a 23.11 foot/7.04 meter "counterpoise" wire from the tuner ground connection.

INITIAL RESULTS:

Like the 30 meter inverted vee previously made, the homebrewed ground plane performed very well.  Owing to the vertical element's proximity to ground and the less than ideal slope of the radials, my initial SWR was between 1.5 and 1.7 to 1 across the 30 meter band.  The versa tuner handled that small mismatch without a problem.

My trusty Ten Tec Argosy II ran without complaint through the late afternoon and into the early evening hours.  With 25 watts output, I was getting reports of 569 to 599 from both Hawaii and mainland U.S. amateur radio stations.  My power source was a deep cycle marine battery charged by solar panels.

I'm enjoying the relaxed atmosphere of the 30 meter band with an antenna I built from materials found in the shack.

REFERENCES:

http://searchmobilecomputing.tectarget.com/definition/ground-plane-antenna.
http://www.csgnetwork.com/antennagpcalc.html.
http://youtube.com/watch?v=4Ex-33Jzp5E.

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

I've included a few Amateur Radio News Headlines at the bottom of this post.

Thanks for dropping by today!

Aloha es 73 de Russ (KH6JRM).

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



Thursday, October 17, 2013

A 30 Meter Inverted Vee Antenna. Post #234

The Thirty meter amateur radio band extends from 10.100 MHz to 10.150 MHz.  This sliver of the rf spectrum offers plenty of space for the die-hard cw fan as well as plenty of contacts for those into the various digital modes.  The operators who populate this band are generally friendly and willing to help out those unsure of the digital frontier.  You'll find plenty of action with PSK31 and RTTY as well.  Antennas for this band are simple and inexpensive.  While thirty meters is a good night time DX band, there are some interesting day time opportunities as well, especially towards sunset.  Besides, a few hours on thirty meters will give you some new contacts and an opportunity to improve your cw speed.

So, let's build a simple antenna for this band.  I built an inverted vee for thirty meters last weekend after I finished clearing some brush from my new home site in the Puna District.  I chose the inverted vee option because I had a spare fiberglass mast in my garage and didn't want to lay in a network of ground radials for a vertical antenna.  However, you could design the antenna as a ground plane using only 4 radials.  There are many choices in this area.  Choose the one that best suits your available space. For me, the inverted vee would be easy to build in back of my garage.

MATERIALS:

I decided to use #14 AWG housewire for the two antenna segments.  Using the general formula for a dipole (468/f(MHz)=L), I cut each element for the mid-point of the band (10.125 MHz).  The total length of the antenna would be 46.22 feet/14.09 meters.  Each antenna segment would be cut to a length of 23.11 feet/7.04 meters.

Two ceramic insulators attached at the end of each antenna segment.

Two, 7-foot/2.13 meters wooden posts.  The antenna segments would be tied off with insulators and attached to the posts to form the inverted vee shape of the antenna.

One Budwig HQ-1 center coaxial connector.  That's what I had in the "junk box".

Fifty feet/50.24 meters of RG-8X coaxial cable with UHF connectors. This would be the antenna feed line.

One, 33-foot/10.06 meters MFJ telescoping fiberglass mast.

One, 5-foot/1.52 meters wooden stake to support the mast.

Nylon ties, vinyl electrical tape, soldering tools.

One MFJ-941E Versa Tuner.

Station equipment, including an old Ten Tec Argosy II, dummy load, and a low pass filter.

ASSEMBLY:

The antenna was built on the ground and later hoisted into place.

The antenna elements were soldered to the tabs of the Budwig HQ-1 center connector.  The connections were wrapped with several layers of vinyl electrical tape.

Before I connected the RG-8X feed line, I made an 8-inch/20.32 cm diameter "choke" balun out of several turns of the RG-8X coaxial cable.  The choke balun was taped to the fiberglass mast about 6-inches/15.24 cm below the Budwig center connector.  I then connected the feed line to the center connector.

I taped the feed line to the fiberglass mast to a point just about 10-feet/3.04 meters above ground.

I then raised the mast onto its support stake, tied off the antenna elements to their wooden stakes, and adjusted the shape of the antenna slightly.

The now elevated feed line was run through a small hole in the shack window and connected to the MFJ Versa Tuner.  The Ten Tec Argosy II, the dummy load, and a low pass filter were connected to the MFJ Versa Tuner with some 3-foot/0.91 meter RG-8X patch cords.

INITIAL RESULTS:

With the Drake MN-4 in the system, I was able to keep a 1:1 SWR across the entire thirty meter band.  Without the transmatch, I kept the SWR down to less that 1.5 to 1 across the band.

I made most of my contacts from the late afternoon through the early evening.  I enjoyed both DX (mainland U.S., Canada, and Mexico) as well as local contacts.  My reports varied from 559 to 599 using 50 watts output from the old Argosy II.

As I grow to like thirty meters, other antennas for this band will be used.  But, for now, the simple inverted vee does an excellent job from the Central Pacific.

REFERENCES:

http://www.dxzone.com/catalog/Antennas/30M/.
http://www.k7su.com/verticalpage.html.
http://www.youtube.com/watch?v=xtwLdlm6wsM.
http://www.wa8lmf.net/ham/30m-magloop-ant.htm.
ht-antenna.com/012/.
http://www.arrl.org/hf-vertical.

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.

Saturday, October 12, 2013

The K3MT "Grasswire Antenna". Post #233

How would you like to use what I call the "ultimate stealth antenna" at your deed-restricted location?  While I was doing some research for antennas at my new home location in the Puna District of Hawaii Island, I came across a fascinating article by Mike Toia (K3MT).  Over 20 years ago, Mike designed, built, and used something called the "grasswire antenna" which would serve as a  nearly invisible, yet effective antenna while he traveled from his various jobs.  Although the antenna appears to be a lossy dummy load on steroids, the data revealed by Mike show that this unusual antenna does work--not as well a dipole or a yagi, but it does get contacts in difficult operating situations.

The antenna is ridiculously simple to build and use.  Mike says his design "is an end-fed, longwire antenna that is laid right in the grass."  This would be perfect for those amateurs that have restrictive HOAs and CC&Rs prohibiting outdoor antennas.

Mike's original design used 204-feet (62.19 meters) of #12-#26 AWG magnet wire, a simple trifilar balun, and a counterpoise (laid on the ground) or a ground rod.  He has since shortened his "grasswire"  to 85-feet (25.91 meters), still retaining the balun and the counterpoise wire.  Mike says the "grasswire" is highly resistive with most of the radiation coming from the long end of the wire.  The antenna is vertically polarized.

Although the wire is quite lossy, Mike's data indicate that that the vertically polorized radiation has a 15 to 20 degree takeoff angle, which can be useful for DX.  Mike has also published a part of his operating log showing that the  antenna does do well for DX.

With all of this in mind, I decided to build a copy of the "grasswire" antenna just to see if it works.

I would build and use the antenna at my future home site, along side of the vertical, loop, inverted vee, and flat top horizontal 1/2 wavelength dipole already in use.  One can't have too many antennas, especially when my lot is off the main highway and out of sight of most neighbors.

MATERIALS:

One homebrew trifilar balun to match the "grasswire" with the RG-8X coax feed line.  I used the illustrations in Mike's original article, including the T-200-2 Core material for the balun form.

Eighty-five feet (25.91 meters) of #22 AWG hookup wire I had in stock.  This would be the radiating "grasswire".

Eighty-five feet (25.91 meters) of #22 AWG hookup wire for the "counterpoise".

SO-239 Coaxial connectors to join the balun to the RG-8X coaxial cable and to connect the balun to the radiating element and counterpoise.



Drake MN-4 antenna transmatch.

Several 3-foot (0.91 meters) pieces of RG-8X to connect the antenna transmatch to the low-pass filter, dummy load, and the Swan 100 MX transceiver.

Fifty-feet (15.24 meters) of RG-8X coaxial cable with UHF connectors.  This would serve as the antenna feed line.

ASSEMBLY:

The hardest part was winding the trifilar balun.  I was a little "rusty" in this area.  Once the balun was made, I connected all the other pieces.  Mike has a good illustration in his article...follow this and you won't make mistakes.

I laid out the main antenna element and its counterpoise in straight lines from the balun.  The counterpoise ran at a 90 degree angle from the "grasswire" antenna element.  Both antenna elements were laid on the freshly mown grass in back of the house.  The "grasswire" antenna was oriented to the north-north-east, with a lobe hopefully falling along the west coast of the United States.

I ran the coaxial feed line to the Drake MN-4 and connected the rest of the equipment in the shack with short patch cables.

RESULTS:

The antenna works very well on 40 and 15 meters running approximately 25 watts from the old Swan MX-100.  With a little nudging from the Drake MN-4, 20 and 10 meters tuned up nicely.  I was able to get SWR readings from 1.3 to 1.9 to 1 on these bands.  Reception reports varied from 53 to 57 for ssb and 549 to 579 for cw.  At my location in the Puna District, I had the most satisfactory results on 40 meters (evenings/early mornings) and on 20 and 15 meters (late morning to late afternoon).  Local state contacts were weak--something predicted by Mike Toia when he designed the antenna.

All told, this isn't a bad antenna.  It won't bust pileups and outperform a four-element monobander on a tower.  But the "grasswire" does work, despite its limitations.  The "grasswire" would make a nice portable or emergency antenna.  Those living in restricted operating areas might want to consider this unusual antenna.  It's almost invisible and blends in well with your lawn and garden.  This may be another case of "out of sight, out of mind."  Good luck!

REFERENCES:

f5ad.free.fr/Liens_copes-Ant/G/K3MT%20Antenna%/20gazon.htm.

http://www.rsgbshop.org/acatalog/PDF/StealthAntennas_Sample.pdf.

http://www.radiosurvivalist.com/antennas/Stealth-hidden-camouflage.asp.

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, October 9, 2013

A simple, portable 40-10 meter vertical antenna with counterpoise. Post #232

How would you like to build a 40-10 meter vertical antenna that could be used in portable or emergency situations?  For the relatively low cost of some housewire, a length of 450-ohm ladder line, some clip leads, a few insulators, a 4:1 balun, a small length of coaxial cable, and an antenna transmatch, you could have a simple multiband antenna that will give you hours of fun on your next mini DXpedition to the nearest public park or in your own back yard.  With a  QRP rig, a deep cycle marine battery, and a few solar panels, you can enjoy a few carefree hours without increasing your electric bill.

I have such a station placed in my Odyssey van.  I can operate when the mood strikes me or when a local emergency is declared.  During the quarterly break from my teaching duties, I decided to unpack my portable station and give it a brief "shakedown cruise" at my new homesite in the Puna District of Hawaii Island.

I wanted to relax a bit after a day's work of clearing the land and making small house repairs, and the portable station in the van would a perfect way to get on the air with a minimum of cost and time.

So, after removing the storage cases from the van, here's what I had:

One Yaesu FT-7 QRP rig.  This is an "oldie but goodie".  If you have a more modern rig such as an ICOM-703, a Yaesu FT-817, or an  Elecraft K-2 or a KX3, so much the better.

One 33-foot (10.06 meters) MFJ telescoping fiberglass mast.

Two insulators, three, 5-foot (1.52 meters) wooden stakes, and 2 alligator clips.

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

Sixty-six feet (20.12 meters) of #14 AWG housewire.  This length would make the antenna resonant around 7.088 MHz (the frequency of the Hawaii Afternoon Net).  With ladder line, a 4:1 balun, and an antenna transmatch, I could use the antenna from 40 to 10 meters.

One W9INN 4:1 balun.  A good source for baluns would be DX Engineering.

An antenna transmatch.  I had a spare Drake MN-4 which I use for portable work.

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

Three, 3-foot (0.91 meters) pieces of RG-8X coaxial cable with UHF connectors.

One deep-cycle marine battery and solar panels.

Basic tools.

Assembly:

I first drove the 5-foot (1.52 meters) wooden support stake into the ground with a hammer.  

I measured 33-feet (10.06 meters) from the mast support stake and drove in another 5-foot (1.52 meters) wooden stake.  This stake would support a slightly elevated radial or counterpoise from the base of the fiberglass mast.

The 66-feet (20.12 meters) of #14 AWG house wire was cut into two equal pieces, 33-feet (10.06 meters) each.  One piece would run up the mast and the other would be lead away from the base of the mast at a slight angle to the second wooden post.

One ceramic insulator would be attached to the tip of the mast and would support the vertical element.  The other would be used to tie off the slightly elevated radial at the second post.  Nylon ties were used to secure the vertical element to the fiberglass mast.

An alligator clip lead was soldered to the bottom portion of the vertical element and to the the left end of the elevated radial.  

I hoisted the mast onto its support stake.

The vertical element clip lead was attached to one side of the ladder line.  The elevated radial clip lead was attached to the other side of the ladder line.  The radial wire was attached to a ceramic insulator and tied off at the distant second wooden post.  The end of the elevated radial was now about 3-feet (0.91 metes) above ground.

I led the ladder line to a third wooden post approximately 50-feet (15.24 meters) away from the base of the mast.  This post kept the ladder line off the ground.

The ladder line was attached to the W9INN 4:1 balun, which was secured to the wooden post with nylon ties.

Twenty-five feet (7.62 meters) of RG-8X coaxial cable was attached to the 4:1 balun.  The coax was run to the Drake MN-4 antenna transmatch.  A 3-foot (0.91 meters) piece of RG-8X coax connected the Drake MN-4 to the Yaesu FT-7.  Small pieces of coax were used to connect a dummy load and low pass filter into the antenna system.

Once I connected the Yaesu FT-7 to the deep cycle marine battery, I had a working station.

Initial Results:

With the Drake MN-4, the W9INN balun, and the 450-ohm ladder line in the antenna system, I was able to get an SWR of 1.2 to 1 on 40, 20, 15, and 10 meters.  Even with low power (under 10 watts) from the venerable Yaesu FT-7, I received good reports from both Hawaii and mainland U.S. stations.  I ran the rig for several hours into the early evening.  The system worked.  Best of all , I made it myself.

Once operating was done, I lowered the mast, disconnected the vertical and radial wires, collapsed the antenna, rolled up the ladder line and coaxial cable, and packed the Yaesu FT-7 into its padded box.  The solar panels and deep cycle marine battery were put in special plastic storage bins.  The wooden stakes were cleaned, dried, and put away with the antenna elements.  With the system safely stored in my van, I was again ready for my next mini DX-pedition.

Resources:

http://www.antennex.com/preview/Folder01/lant.htm.

De Maw, Doug (W1FB) (SK).  "Novice Antenna Book."  ARRL, Newington, CT, 06111. 1988. pp. 60-61.

http://www.hamuniverse.com/slopinginvl.htm.

http://www.vk1od.net/antenna/InvertedL.htm.

Thanks for joining us today.

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

Aloha es 73 de Russ (KH6JRM)

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









Saturday, October 5, 2013

A radiating dummy load antenna, part 2. Post #231

In my last post, I recounted a conversation I had with Dean Manley (KH6B) on Monday, 30 September 2013 concerning the use of "dummy loads" as emergency antennas.  The conversation centered around Hank Scharfe's (W6SKC/7) attempt to get some power into his 150-ft (45.73 meters) grounded inverted "L" antenna following the failure of his automatic antenna tuner.  Hank was successful in meeting his scheduled nets when he used his Waters dummy load with a "T" UHF connector to feed some rf to his antenna.  Although most of his power was confined to the dummy load, there was sufficient power delivered to his antenna to complete his schedules.

Dean and I have made several such antennas for field day and portable operations.  In fact, I mentioned my own experience with a dummy load antenna back in September 2012 when I was a newly licensed novice operator.  That contact surprised me, and that experience has kept me interested in radiating dummy loads ever since.  So, while I had some time off from my substitute teaching assignments, I decided to make an emergency antenna using a dummy load and the few milliwatts I could squeeze from the lash up to make some local contacts.  The results were gratifying.  I made some excellent ssb and cw contacts on 40, 20, and 15 meters with my trusty Heathkit  Cantenna dummy load performing most of the work.

MATERIALS:

One 33-ft (10.06 meter) MFJ telescoping fiberglass mast.  The mast supported a 40 through 10 meter inverted vee fed by 450-ohm ladder line running into a W9INN 4:1 balun and a Drake MN-4 antenna transmatch.  I had a spare 40 meter dipole connected to a Budwig HQ-1 coax center connector and 50-feet (15.24 meters) of RG-8X coaxial cable in the garage.

I lowered the inverted vee, stored it in the garage, and hoisted the dipole to the top of the mast where I configured it as an inverted vee.  The antennas were raised and lowered with a halyard and pulley system.

Two 5-foot (1.52 meters) wooden stakes to support the ends of the inverted vee.  The stakes were also used for the vee fed by the ladder line.

One Heathkit Cantenna dummy load.

One UHF "T" connector.

Three-feet (0.91 meters) of RG-8X coaxial cable with UHF connectors.

Shack equipment, including an SWR meter, low pass filter, and the trusty Swan 100-MX transceiver.

ASSEMBLY:

One I lowered the ladder line-fed inverted vee, I hoisted the 40 meter dipole with the Budwig center coax connector to the tip of the fiberglass mast.  The halyard and pulley system came in very handy in making a quick and smooth transition from ladder line to coax feedline.

I ran the RG-8X coaxial cable through a homebrewed window panel to the equipment table.  I screwed the coaxial "T" connector into the Heath Cantenna.  One port went to the Swan 100-MX transceiver and the other port went to the coax leading to the outdoor inverted vee.

RESULTS:

I ran approximately 50 watts cw and 75 watts ssb into the antenna feed line.  The SWR meter showed 1:1 on all frequencies from 7.088 MHz (Hawaii Afternoon Net frequency) to 29.7 MHz.  Although most of the power was channeled to the Cantenna, there was enough "juice" left over to energize the antenna.  Reports varied from 549 to 579 on cw and 53 to 58 on ssb, depending on time of day and band in use.  Ten meters was very noisy, so I didn't spend much time using that band.  My best reports came from 40 and 15 meters.

Despite the absorption of most of the power by the dummy load, some power was running up the feedline.  Like W6SKC/7's experience, I noticed this modification seemed to be quieter than my other inverted vee.

This is a compromise antenna with high losses, but, in an emergency, a dummy load can substitute for an antenna "tuner" if the need arises.  This was an enjoyable and educational experience.  I replaced this temporary antenna with my previous inverted vee fed by ladder line.  If I ever need an emergency antenna, I know what to do.

REFERENCES:

Personal conversation with Dean Manley (KH6B) on 30 September 2013 at the Hilo, Hawaii Jack In The Box Restaurant.

The "Aerials" column from "World Radio", December 1992.  The column was the brainchild of the late Kurt N. Sterba (aka John E. "Jack" Althouse) (K6NY).  Althouse died on 15 September 2013 after suffering a massive stroke.  He was the president of Palomar Engineers.

ARRL Letter, 19 September 2013 (http://www.arrl.org/).

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Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Wednesday, October 2, 2013

The radiating dummy load. Post #230

On Monday, 30 September 2013, I had the day off from my substitute teaching assignment and I decided to meet with some of my amateur radio friends at the Hilo, Hawaii Jack In The Box Restaurant for informal discussions concerning amateur radio.  The Hawaii QRP Club holds daily meetings at the popular fast food restaurant around 0800 W.  Most of the time, the meetings are concerned with the usual topics of rigs, DX, antennas, and the latest HOA restrictions on ham operators.  Monday's meeting was going to be different.

By the time I arrived at 0800 W, most of the group had departed for their jobs and other concerns, leaving only myself, my xyl, and informal club president Dean Manley (KH6B) left to "hold the fort."  Several times in the past I had lamented my fate in using compromise antennas in the various homes I rented while I was fully employed as a news announcer for KKGB-FM and KHLO-AM in Hilo.  Now that I was building a new home on a larger property, I had more space to build "real" antennas without some HOA forcing itself on my operating habits.

Dean handed me an article published in the December 1992 edition of "World Radio", which described how  Hank Scharfe (W6SKC/7) used a dummy load to get back on the air after his "automatic high-speed antenna tuner committed suicide."  I found the article fascinating.  I'm offering a few quotes from the article, hoping that those in similar circumstances can return to the air despite failure of their antenna matching devices.

Although Hank could hear well on his 150-foot Grounded Inverted L, the Icom "781 would not generate any power to what was probably a very high SWR.  The little 'band expander' tuner in the 781 was of no use at all, so I decided I had to trick the 781 into generating some useable (sic) power.  I screwed a coaxial 'T' connector into my Waters dummy load.  Of the other two ports, one went to the 781 and the other went to the GIL's feedline."

"The power meter on the dummy load indicated 150 W on peaks, and the inline SWR bridge indicate the world's finest SWR, 1:1 on all frequencies between 1.8 and 29.7 MHz!  Best of all, instant loading."

"I checked into my normal sked and Tucson (60 miles away) gave me my usual 30 over 9 report.  Then Yuma (250 miles to the west) volunteered that I was the same old 20 over 9."

"Although the power meter in the dummy load was still indicating 150 W, it was obvious that some power was escaping up the GIL's feedline.  The only noticeable difference was that the receiver seemed to be 'quieter.'  Being a low-Q lashup, i.e. broad-banded, the residual noise was down.  I thought the coupler with a 10 to 20 millisecond tuneup time was fast, but zero tuneup time is faster and more convenient when band-hopping."

"Not wanting the big Waters DL on the operating table all the time, I replaced it with a 15 W dummy load from Radio Shack...it handles the 150 W of the SSB rig without getting hot, since the duty cycle SSB is probably less than 5 percent.  For a few dollars more, Ten-Tec and MFJ offer 300 W units that will handle 1500 W SSB easily."

So, there you have it...an emergency antenna using a dummy load to help your random wire radiate.  I've done the same thing using a Heathkit Cantenna, a "T" coax connector, and a simple coax-fed dipole.  Like W6SKC/7, I've made contacts on several amateur radio bands, including 40, 20, 15, and 10 meters.  The reports were a bit down from my usual reports at home, but I did radiate a signal and was able to carry on conversations.  I suppose most of my power was absorbed by the cantenna, but some power in the milliwatt range was "squeezed out" and I had enough energy to make contacts.

You may want to try this temporary antenna project just to see what you can do.

REFERENCES:

Sterba, Kurt N. (John E. "Jack" Althouse, K6NY (SK).  Article published in the Aerials column.  "World Radio".  December 1992.  Note:  John Althouse (aka Kurt N. Sterba) died 15 September 2013 in San Diego, California.  He was the president of Palomar Engineers.

Personal conversation with Dean Manley (KH6B), 30 September 2013, 0800 W, at the Hilo, Hawaii Jack In The Box Restaurant.

http://www.eham.net/articles/9054.

http://www.ehow.com/how_6459249_use-dummy-load-ham-radio.html.

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.