Monday, July 29, 2013

Hawaii Island Hams help during tropical storm warning. Post #217

Today at 1700 hours local time, The National Weather Service downgraded Tropical Storm "Flossie" to a tropical depression.  The weakened storm swept over Hawaii Island, leaving heavy showers, gusty winds, high surf, and power interruptions in its wake. Thankfully, no one was injured.  Damage from the storm was minimal.

During the warning period, members of the Big Island Amateur Radio Club stood by to help at Hawaii County Civil Defense, the Hilo Medical Center, and at various American Red Cross stations across the island.

The Hilo International Airport reported winds between 30-35 knots early this afternoon (Monday) with rainfall gauges registering 2 to 4 inches (5.08 to 10.16 cm) of rain.  The situation could have been a lot worse, with early forecasts predicting up to 10 inches (25.4 cm) or more of rain by this evening.

The remaining portions of "Flossie" will move past West Maui, Molokai, Honolulu (on Oahu), and Kauai later this evening.  Rainfall is expected to be in the 2 to 4 inch (5.08 t 10.16 cm) range.

Considering everything, Hawaii Island residents and local amateur radio operators were well prepared for this storm, with civil defense officials providing updates over island radio and television stations.  Things could have been a lot worse.

At my QTH in Laupahoehoe along the Hamakua Coast, the storm left 1.5 inches (3.81 cm) of rain in the rain gauge.  Wind gusts were in the 20 to 25 knot range.

There was no damage to my antennas or to my home.  I managed to raise all of my masts to their operating positions without a problem.  Before the arrival of the storm, I had lowered all masts to ground level, disconnected feed lines,  and unplugged all home appliances and audio equipment from the commercial mains.  Commercial power was not a concern for my amateur radio station, since I use solar panels and deep cycle marine batteries to power my ham equipment.

This weak storm provided an opportune time for Hawaii Island amateur radio operators to test their emergency preparedness procedures and equipment.  My "go kit" was already in my van when the first civil defense message was issued on Friday.

We were lucky this time.  There's no room to hide in the Central Pacific.

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 very wet Hamakua Coast of Hawaii Island.

Saturday, July 27, 2013

A 40-Meter Inverted L Antenna. Post #216

During the past few weeks, I've been experimenting with the versatile inverted L antenna for my small house lot.  I find the antenna simple, inexpensive, and easily concealed.

An inverted L is a bent quarter-wave Marconi vertical fed against a system of surface, buried, or elevated radials.  The vertical segment should be as high as possible, with the remaining length running horizontal to a nearby tie off point.  Coaxial feed line can be used for monoband operation or 450-ohm ladder line can be employed if multiband use is planned.

MATERIALS:

Two vertical structures to support the antenna--one for the vertical segment and the other to tie off the horizontal wire running from the top of the mast.  I had a homemade 20-foot/6.09 meters pvc mast under the house and a convenient Norfolk Pine Tree at the edge of my property to support the horizontal portion of the antenna.

Sixty-six feet/20.12 meters of #14 AWG house wire for the radial system and the antenna element.

Three, 6-foot/1.82 meters wooden stakes.  One stake would support the vertical mast, while one stake would support an elevated radial running from the mast.  The elevated radial would be approximately 5-feet/1.52 meters above ground.  The remaining wooden stake would support the 450-ohm feed line midway between the mast and the garage wall, where a 4:1 balun would be placed.  The ladder line was not allowed to touch the ground.

If you plan on monoband operation, you can use 50-ohm coaxial cable for your feed line.

Four ceramic insulators, one to tie off the horizontal portion of the antenna to the tree, one to attach to the tip of the mast, one to tie off the bottom of the antenna element  on the mast, and one to tie off the elevated radial wire.

A launching system to put the upper portion of the antenna through a tree branch.  I used a slingshot, 50-feet/15.24 meters of fishing line, and a sinker to place the antenna up in the tree.

A W9INN 4:1 balun.

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

A suitable antenna transmatch.  I use a Drake MN-4 in the shack.

Various tools, including soldering equipment, wire cutters, vinyl electrical tape, nylon ties, etc.

Short coaxial cable patch cords to connect the Drake MN-4 to the Swan 100 MX transceiver, the low pass filter, and the dummy load.

ASSEMBLY:

Using the general formula 234/f (MHz)=L (ft), I calculated the length of the quarterwave vertical for my chosen frequency of 7.088 MHz.  This came out to 33.01 feet/10.065 meters.  I rounded off the figure to 33-feet/10.06 meters.  With my lowest frequency in the 40-meter amateur radio band, I could have multiband capability between 40- and 10-meters with the use of 450-ohm ladder line as my feed line.

Although many antenna experts recommend a slightly longer length for the radial wire (about 5%), I decided to keep the radial wire the same length as the antenna element (33-feet/10.06 meters).

Once I cut the wire to the proper length, I attached the antenna wire to the monofilament fishing line and shot it over a pine tree bough approximately 35-feet/10.67 meters above ground.  I left the antenna wire loosely hanging from the tree branch until I connected the wire to the top of the mast.

I attached a ceramic insulator to the tip of the mast and then threaded the antenna wire from the tree branch through the top insulator and down the vertical 20-foot/6.09 meter mast.  The antenna wire would be secured slightly above ground once I got the antenna adjust for proper tightness.

I hoisted the pvc mast onto its support stake, tied off the fishing line holding the upper portion of the antenna to the pine branch, and tightened the antenna by bringing the vertical portion down to a point approximately 5-feet/1.52 meters off the ground. Nylon ties were used to secure the wire to the pvc mast. The antenna sloped slightly upward from the tip of the mast.  At the 5-foot/1.52 meter mark on the mast, I attached and soldered the 450-ohm ladder line to the vertical element and the elevated radial.  The radial was tied off at a wooden stake approximately 5-feet/1.52 meters above ground.  The elevated radial ran through the garden and was not visible from the street.

The ladder line was run off at a right angle to the vertical mast to a 6-foot/1.82 meters wooden stake a short distance away.  The ladder line was kept off the ground until it was attached to the W9INN 4:1 balun mounted on the garage door.

A 25-foot/7.62 meters length of RG-8X coaxial cable was connected to the 4:1 balun. The cable was routed through a homebrewed patch panel in the shack window to the Drake MN-4 antenna transmatch.  Short patch cords connected the transmatch to the Swan 100 MX, the dummy load, and the low pass filter.

INITIAL RESULTS:

With the help of the Drake MN-4 transmatch, I was able to get a SWR of 1.1 to 1 on the 40, 20, 15, and 10 meter amateur radio bands.  With an output of 50 watts, I was able to get reception reports between 569 to 599 on cw and 55 to 59 on ssb.  My best band was 40-meters, followed by 15- and 20-meters, where the tuning was a bit more critical.

Performance should increase when I add more elevated radials.  Fortunately, there is sufficient room to run a few more radials through the garden and in the area near the Norfolk Pine Tree.  I ran the single elevated radial as an experiment.  It works, but more radials would surely help the efficiency of the antenna.

Since the mast is colored a dull grey, it can hardly be seen from the street in front of my house.  The antenna wire is nearly invisible, too.

For an inexpensive antenna, the performance is adequate for my purposes.  I get great local coverage and decent DX from my location on Hawaii Island.

REFERENCES:

http://www.vk1od.net/antenna/InvertedL/InvertedL.htm.
http://www.clive.wankling.dsl.pipes.com/l.html.
http://www.amateur-radio-wiki.net/index.php?title=Inverted-L_antenna.
http://www.hard-core-dx.com/nadidx/antenna/wire/antenna.html.
http://www.hamuniverse.com/slopinginvl.htm.
http://www.antennex.com/preview/Folder1/lant/lant.htm,

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

For the latest Amateur Radio News, visit my news site--http://kh6jrm.com.  I've included a few headline stories at the end of this post.

Aloha es 73 de Russ (KH6JRM).

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















Wednesday, July 24, 2013

A Multiband "Lazy L" antenna. Post #215

One of my favorite antenna guides is a book by the late Doug DeMaw (W1FB) titled the "Novice Antenna Notebook."  Although it is a slim volume, it contains most of the facts, construction principles, and modifications needed to erect simple, inexpensive, and effective antennas.

I bought the book 25 years ago while I was mentoring (elmering) a newly licensed ham in my neighborhood.  Since I'm not a technical genius, I decided to consult a basic antenna primer that could be used by the new licensee as well as myself.  I wasn't disappointed.  DeMaw's writing is down to earth, clear, and largely without complicated formulas for the beginning ham.  I still have this wonderfully simple volume squeezed in between other antenna tomes, including the ARRL Antenna Book, the ARRL Handbook, and various RSGB publications.

What prompted me to consult DeMaw this late in my amateur radio "career" (I was licensed as a novice back in 1977), was the need to erect a simple multiband antenna that would give good results at a modest cost.  The antenna could also serve as a backup antenna for portable and emergency operations.

According to DeMaw, my self-named "Lazy L" antenna will give "good performance from 40 through 10 meters if it is situated well away from nearby conductive objects, such as house wiring, phone lines and metal buildings.  It may be used also on 80 meters, but the efficiency is lower than on the higher bands."

With that in mind, I built the new "skyhook" in about two hours.  I was in no rush.  I just wanted to get something simple and effective on the air.

MATERIALS:

One 33-foot/10.06 meters fiberglass telescoping mast.  I decided to use an extra MFJ mast stored in the garage.  You could also make a suitable mast from pvc pipe.

A pulley and halyard system to raise the vertical portion of the "Lazy L" to the top of the mast.  The upper portion of the "L" would later be led off the top of the mast at a 45-degree angle.

Three, 5-foot / 1.52 meters wooden posts.  One post would support the mast and the other two posts would support the lower portion of the "L" and act as an elevated radial or counterpoise.

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

A 4:1 balun.  The balun would connect the ladder line to a length of coax entering the shack.

25-feet/7.62 meters of RG-8X coaxial cable.  The coax would run from the balun/ladder line combination to an antenna transmatch in the shack.

A Drake MN-4 transmatch.  Actually, you could use any commercially made "antenna tuner" to complete the antenna system.  I've used my trusty Drake MN-4 since I was first licensed.  It's a good "tuner."

Soldering gun/iron, basic tools.

4 ceramic insulators...two for the vertical section and two for the elevated radial/counterpoise wire.

Transceiver.

ASSEMBLY:

I decided to cut the "Lazy L" to be resonant on 7.088 Mhz, the frequency of the Hawaii Island Afternoon net.  Using the general formula, 468/f (MHz)=L (ft),  I measured and cut two equal lengths of #14 AWG housewire. Each element (the vertical and its elevated radial) came to 33.01 feet/10.064 meters.  I rounded off the measurement to 33-feet/10.06 meters.

I attached a ceramic insulator to each end of the vertical element and the elevated radial/counterpoise.

I pounded in two 5-foot/1.52 meter wooden stakes.  The stakes would support the elevated radial/counterpoise approximately 3-feet/0.91 meters above the ground.

A third 5-foot/1.52 wooden stake would support the fiberglass mast.

A pulley and halyard system to raise and lower the vertical section of the antenna.  I used a brass pulley from the Hilo, Hawaii Ace Hardware store and 75-feet/22.86 meters of dacron rope I found at WalMart.

I attached 50-feet/15.24 meters of 450-ohm ladder line to the vertical element and the elevated radial/counterpoise.  The connections were soldered and covered with several layers of vinyl electrical tape.

I raised the vertical segment of the antenna with the halyard and pulley system.  I then led the vertical element off the top of the mast at a 45-degree angle to the nearest stake supporting the elevated radial/counterpoise.  The antenna took the form a "Lazy L" with the elevated radial/counterpoise running parallel to the ground to the end tie-off stake.  A few short pieces of dacron rope secured the ceramic insulators of the elevated radial to the posts.

The 450-ohm ladder line was routed at a right angle to the sloping vertical element.

The ladder line was attached to the 4:1 balun on the garage wall.  The balun was approximately 7 feet/2.13 meters above ground level.  At no time did the feed line touch the ground.

A 25-foot/7.62 meters piece of RG-8X coaxial cable was connected to the 4:1 balun and led into the shack through a homemade patch panel in the room's window.  MFJ sells several versions of this panel.  I just used a pine board and drilled my own holes.

The coax was connected to the Drake MN-4. Short lengths of RG-8X connected the transmatch to a dummy load, a low pass filter, and the Swan 100-MX.

INITIAL RESULTS:

With the use of the Drake MN-4 transmatch, I was able to attain a SWR of 1:13 to 1 on 40, 20, 15, and 10 meters.  The tuning was a bit "tight" on 20 and 10 meters, but I was able to get SWR readings below 1.5 to 1 in most cases.  I tried the antenna on 80 meters, but I wasn't impressed with the results.

Most contacts were made using 10 watts or less on CW and 20 watts or less on SSB.  Depending on the band selected and the time of day, my CW contacts reported 569 to 599, while my SSB efforts netted reports of 55 to 58.

For a simple, no-frills antenna, the "Lazy L" performs very well.  I had most of the materials on hand, so my financial outlay was minimal.

DeMaw's book is full of easily- built antennas such as mine.  I'm going to build a few more of these basic antennas before the year is over.  Good luck in your antenna building efforts.

REFERENCES:

DeMaw, Doug (W1FB).  "Novice Antenna Notebook".  Copyright 1988.  ARRL.  Newington, CT. 06111. pp. 60-61.
http://www.antennex.com/preview/Folder01/lant/lant.htm.
http://www.eham.net/articles/27401.
http://www.w6sdo.com/160M.html.
http://www.hamuniverse.com/slopinginvl.html.

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, July 20, 2013

Ten Basic Antenna Truths. Post #214

Sometimes knowledge comes from the strangest places.  Take today, for instance.

While my van was having a routine maintenance check at my local Honda dealer (I have an Odyssey van), I ran into an Dean Manley (KH6B), one of my oldest friends and former station engineer at Hilo radio station, KHLO-AM.  I worked at this station from 1976 to 2011.  We discussed a variety of antenna ideas, including improving the homebrewed antennas we use at our stations.  I consider Dean an expert in this area.  He has spent many years building and upgrading antenna systems for  AM and FM stations, both commercial and nonprofit.

Anyway, we spent a good half-hour discussing some ideas, including his current project--a 40-meter vertical beam which Dean uses for the Hawaii Afternoon Net.  Before we parted, he gave me a copy of a handout he made for members of the Hilo Amateur Radio Club.  The one-sheet article, entitled "HF Antennas 101" by Van Field (W2OQI), appeared in the September 2004 issue of "QST".

What's remarkable about this informative piece is the easily employable principles of HF antennas--concepts that we often use without thinking, but are valuable in designing and building effective antennas.

Briefly summarized are the "10 tips and truisms that every ham should know."

1.  An antenna does not have to be resonant to work.  Van says the sole reason to use a resonant antenna is to remove the need for an impedance-matching device, such as an "antenna tuner."  The only time I've used an antenna tuner is when I go on 30 meters with my backup rig--a Ten Tec Argosy II.  My old Drake MN-4 doesn't cover 30 meters, so I try to use resonant antennas cut for 10.100 MHz.  Van notes that open wire feeders used with an antenna tuner and a basic dipole make great multiband antennas.  All of my inverted vees, loops, and slopers use 450-ohm ladder line in conjunction with a 4:1 balun and a 50-ohm feedline to the old Drake MN-4.

2.  Two wires are needed to power a lamp.  The same is true of antennas.  In this paragraph, Van says the use of tuned feeders to a balanced antenna such as a dipole eliminates some of the rf feedback problems of unbalanced feed lines using coaxial cable.  Of course, coaxial cable feed lines can be used successfully if operators use choke baluns or 1:1 baluns at the center of the dipole.

3.  Antenna "gain" is derived by shaping and aiming RF where you want it to go.  Beam antennas are the most common example of directing energy to a particular area.  Beams can be horizontal and vertical.

4.  The function of an antenna tuner is to effect a match between the output of a transmitter and the input of an antenna system.  Van suggests the use of an antenna transmatch to compensate for the narrow ranges of most internal tuners.

5.  A wire antenna doesn't always have to be center fed.  Van cites the "end-fed Zepp" and the Windom antenna as successful off-center fed dipoles.  However, these antennas require a radial or counterpoise system attached to the ground side of the antenna tuner.

6.  A dipole antenna does not have to be perfectly horizontal.  Dipoles can be configured to fit the available space.  I've used inverted vee dipoles, half-wavelength slopers, and even vertical dipoles with excellent results.

7.  Vertical antennas shorter than half a wavelength need a ground system.  This usually takes the form of buried radials, surface radials, or elevated radials.  Elevated radials are easier to install.

8.  With vertical antennas there is no such thing as too many radials.  My friend Dean (KH6B) says most commercial AM radio stations install up to 120 buried 1/4 wavelength radials.  Having installed a radial system at an AM radio station, I can verify that the project entails a lot of work on a large expanse of land.  For most hams, a modest system of 20 to 30 on- surface or buried radials should boost antenna efficiency.

9.  Having a 1:1 SWR does not mean you have a good antenna.  It only means that you have an impedance match between your rig and your antenna system.  A perfect match says little about how efficiently your antenna is working.  A vertical antenna with a poor or non-existent radial system can be adjusted to measure a 1:1 SWR, but the antenna is so inefficient that a large portion of the RF heats worms.  Even a dummy load can measure a SWR of 1:1.

10.  Always use the best feed line you can afford.  Better coax will cost you more money, but "this is the cable that is carrying your precious RF signal to and from your antenna."  A low-loss cable "will pay off in better antenna performance."

So there it is---some fundamental guidelines that should help you design an efficient, cost effective antenna that will give you many hours of enjoyment.

REFERENCES:

Personal conversation with Dean Manley (KH6B) on 20 July 2013.

Ford, Steve (WB8IMY).  "The Classic Multiband Dipole Antenna".  QST, March 2004.

Field, Van (W2OQI).  "HF Antennas 101".  QST, September 2004.

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, July 16, 2013

A 3/2 wavelength sloping dipole for 20 meters. Post #213.

One of the easiest and least expensive antennas for the amateur radio operator is the sloping dipole or "sloper."  Ed Noll (W3FQJ) defines the sloper as "a slanted half-wave antenna with one end of the antenna attached to (a) mast top and other end near to ground level."  According to Noll, the sloper shows "a modest directivity in the direction of its slope and considerably less signal pickup from its rear."  A well-designed half-wave sloping dipole can fit in a small city lot using a mast between 20 to 30 feet (6.09 to 9.23 meters), two dipole elements cut to your preferred frequency, a few insulators, a couple of tie-down stakes, and sufficient 50/72 ohm coaxial cable to reach your shack.  Multiband operation is possible using 450 ohm ladder line, a 4:1 balun, and an antenna transmatch.

Since most of my ladder line was being used for other antenna projects, I decided to use 50 feet (15.24 meters) of RG-8X coaxial cable with UHF connectors for my feed line.  The antenna would be a single band affair, concentrating on 20 meters.  I wanted some gain and directivity for the antenna, so I decided to make the antenna 3/2 wave lengths long, with each dipole leg being 3/4 wave length long for my chosen frequency of 14.200 Mhz.

MATERIALS:

A 33-foot (10.06 meters) telescoping fiberglass mast.  I had a spare MFJ fiberglass mast that would serve as the upper support of the antenna.

Four, 5-foot (1.52 meter) wooden stakes.  The stakes would serve as tie-off points for the sloping dipole.  The stakes were placed NW, NE, SW, and SE of the mast, giving me some directivity in those directions.

A lanyard system using a pulley and approximately 75-feet (22.86 meters) of Dacron rope.  The pulley was attached to the top of the mast and would be used to hoist the sloping dipole into position.

A 5-foot (1.52 meter) support stake for the fiberglass mast.

Using the general formula for a quarter wavelength wire, 234/f (Mhz)=L(ft), I cut a 3/4 wavelength of wire for each element.  This amounted to 50.14 feet (15.28 meters) per leg.

One Budwig HQ-1 center coax connector.

Two ceramic insulators.

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

Antenna transmatch to handle any mismatch in the sloping dipole.  I had a Drake MN-4 available (great "tuner").

Soldering iron, basic tools, nylon ties, vinyl electrical tape, wire cutters, etc.

ASSEMBLY:

The antenna was built on the ground.  I hoisted the mast onto its support stake with sufficient rope from the halyard to lift the sloper into position after construction.

Before I attached the coax to the center connector, I wound a 6-turn, 8 inch (20.32 cm) rf choke out the coaxial cable, secured the choke with vinyl electrical tape, and then attached the end of the RG-8X to the center connector.

I soldered the upper portion of the dipole to the + end of the center connector and the lower segment of the dipole to the - end of the center connector.  All connections were covered with vinyl electrical tape.

The upper portion of the sloper was attached to a ceramic insulator, which was then connected to the halyard.  I hoisted the upper half into position and secured the remaining rope at the base of the mast.

The bottom segment of the sloper was attached to a ceramic insulator, which was connected by a short piece of Dacron rope to a 5-foot (1.52 meters) tie-off post.

I ran the remaining RG-8X to the shack and hooked it up to the Drake MN-4.  Short coaxial cable patch cords connected the dummy load, low pass filter, and Yaesu FT-7 QRP transceiver to the transmatch.

INITIAL RESULTS:

Using the Drake MN-4 transmatch I was able to keep the SWR below 1.1 across the 20 meter amateur radio band.  SSB reports have varied between 56 to 59, with cw reports falling between 569 and 599.  All this was done with the old Yaesu FT-7 putting out around 10 watts.

A hidden benefit of this 3/2 wavelength 20 meter dipole was getting resonance at 7.100 MHz in the 40 meter band and finding some matching in the 75 meter band.  According to Noll, "reasonable 75-meter results can be obtained by using a tuner to establish resonance on the 75-meter band."  I was able to get a decent signal out on 40-meters, thanks to the Drake MN-4.  Also, I was successful in getting  good signal reports on the upper reaches of the 75-meter band (above 3.800 MHz).  Although the antenna works best on 20 meters, it can be used on 40/75 meters with very careful tuning.  For my purposes, I'll use the antenna for 20 meters only.

I had fun making this antenna and so will you.  Another good point...this antenna doesn't require a ground radial system.

REFERENCES"

Noll, Edward M (W3FCJ).  "Easy-Up Antennas for Radio Listeners and Hams."  Limited Edition, 1991.  MFJ Enterprises, Inc.  Mississippi State, MS, 39762.  pp. 110 to 126.

http://www.findatlantis.com/wiki/index.php/20mSloping_Dipole.

http://www.youtube.com/watch?v=mgEibY3INHo.

http://www.angelfire.com/mb/amandx/dipole.html.

http://www.qsl.net/ta1dx/amateur/practical_dipole_antenna.htm.

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

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

Thanks for joining us today.

Aloha es 73 de Russ (KH6JRM).

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

 

Saturday, July 13, 2013

My favorite stealth antenna. Post #212

Amateur radio operators who live in deed restricted homes and apartments face a variety of antenna problems.  The amateur radio press is full of stories describing the "no outdoor" antenna rules of OHAs and CC&Rs.

Despite these reports, many amateurs have been able to build effective indoor and outdoor antennas to pursue their radio interests. From flagpole antennas to attic beams, hams have used creativity and "stealth" to get and stay on the air.

In my case, the adoption of "stealth" antennas was forced on me by natural circumstances and not necessarily by highly critical neighbors.  In fact, my neighbors are good people who tolerate my amateur radio pursuits as long as I don't ruin their television reception or interfere with their entertainment systems.  Although many people in my neighborhood get excellent television via cable television providers, my immediate neighbors get their tv programming over the air using the familiar deep fringe antennas marketed by Radio Shack and others.  The adoption of digital over the air television transmissions has lessened potential tvi problems, but, just to be safe, I always use a low pass filter in my antenna systems and operate my station at qrp power levels (10 watts or less).  I also lower my antenna masts (vertical and inverted vee) after I close out my radio day.  So far, this arrangement has worked.

Now to the stealth part.  When hurricane "Iniki" struck Kauai head on in 1992, I learned first hand how fragile most antennas were. Fortunately, the storm just grazed Hawaii Island.  Kauai's communications infrastructure was a mess, with amateur radio operators providing most of the initial communications links with the outside world.  In the past, high winds sweeping down from Mauna Kea have damaged my pvc and fiberglass masts, despite my best efforts at guying the structures.

Since Hawaii gets occasional visits from tropical storms and hurricanes, I thought it a good idea to have a protected antenna at the home qth.  The antenna would be protected from the weather, capable of providing emergency communications throughout the state of Hawaii, and be nearly invisible from peering eyes.

The antenna would be a full- wavelength 40 meter loop under my house.  My home is built on a post and pier system tied to concrete pads, an arrangement that provides some protection against earthquakes and floods.  The house is approximately 3 feet/0.91 meters above the ground.

The antenna would be fed by a length of 450-ohm ladder line, coupled to a 4:1 balun.  A short piece of coaxial cable would connect the balun to an antenna transmatch and then onto the rig and associated station equipment.

MATERIALS and ASSEMBLY:

I designed the loop to be resonant on the daily Hawaii Afternoon Net frequency of 7.088 MHz.  Using the general formula 1005/f (MHz), I calculated an antenna length of 141.78 feet/43.22 meters.
I used #14 AWG household wire for the loop antenna.

The antenna fit fairly well under my house, with a short turn into the garage to make the total length come to what was calculated.  I attached 20 feet/6.09 meters) of 450 ohm ladder line at an intersecting corner of the loop.  That connection was soldered and wrapped with several layers of vinyl  electrical tape.

The ladder line was run under the door of the shack and was connected to a W9INN 4:1 balun.  A 3-foot/0.91 meters piece of RG-8X coaxial cable with UHF connectors ran from the balun to my trusty Drake MN-4 transmatch.  Several pieces RG-8X coaxial cable connected the transmatch to the Yaesu FT-7, the low pass filter, and the dummy load.  I also attached a 33-foot/10.96 meters piece of #14 AWG housewire to the ground lug of the Drake MN-4. 

With the help of the Drake MN-4, the under the house loop works on all bands between 40 and 10 meters.  Since the loop antenna is close to the ground, most of the signal goes straight up.  This low mounted NVIS (near vertical incident skywave) antenna is perfect for local statewide coverage out to about 200-300 miles/320-480 kilometers. 

The performance of the full wavelength loop is acceptable on 20, 15, and 10 meters.  This certainly is no DX antenna.  But it does work well for local and statewide coverage.

So, if one of my inverted vees or verticals succumbs to the forces of nature, I still have a dependable antenna for local emergency HF work.  The antenna can't be seen from the street or from any of my neighbor's homes.

A low mounted loop may be the solution to your antenna problem.  You could also run a loop around the ceiling of your apartment and feed it with 450 ohm ladder line into a balanced antenna tuner.  If you operate at qrp levels, rfi will be kept to a minimum. 

ADDITIONAL RESOURCES:

http://voices.yahoo.com/stealth-ham-radio-antennas-guide.
http://www.radiosurvivalist.com/antennas/build-stealth.asp.
http://www.eham.net/articles/29676.
http:/www./ac6v.com/antprojects.htm.

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, visit my news site--http://kh6jrm.com.  I've included a few headline stories at the bottom of this post.

Thanks for joining us today.

Aloha es 73 de Russ (KH6JRM).

BKJ29jx15--along the beautiful Hamakua Coast of Hawaii Island.

Thursday, July 11, 2013

An 80-Meter Vertical Helix

Like many amateur radio operators, I live on a small lot surrounded by neighbors, utility lines, and civic-minded citizens concerned about the "attractiveness" of my community.  Whether by design or outright fear, I've adopted the "stealth" approach to ham radio antennas.  It's the old "out of sight, out of mind" idea applied to amateur radio antennas.

The amateur radio press is full of articles describing the struggle of amateur radio operators to pursue their hobby under the burdensome regulations of CC & Rs, HOAs, and other civic minded citizens who object to antenna farms.  So far, my modest verticals, loops, and inverted vees have blended well with the vegetation and trees bordering my small backyard.  Vertical antennas have always been a problem because of the limited space for a radial system.  There are times, however, where a shortened vertical for the lower HF bands (such as 80/75 meters) is necessary where horizontal space is lacking.

In one of my recent posts, I described an inverted "L" antenna I built for  80 meters--a band I find difficult to use because of my restricted space.  The antenna was a joy to build and I got many contacts despite a mediocre ground system.

The one drawback I had was in quickly deploying and taking down the antenna when I was done operating for the day.  Call me extremely cautious, but I believe in lowering my antennas before I "call it a day", partly to prevent evening thunderstorms and lightning from affecting my antennas and partly because I wanted to reduce the visual impact of any antenna I build.

So, enter the helically-wound vertical for 80 meters.  My antenna was based on a design originally presented in QST by Gary L. Ellingson (WA0WHE).  The article was reprinted in "The ARRL Antenna Anthology" back in 1978.

From my initial research in various ARRL publications, I discovered that a half-wavelength of wire for a chosen frequency wound in a helix on an insulating form such as a wooden pole, a fiberglass pole, or even pvc pipe could duplicate the performance of a standard 1/4 wavelength vertical antenna.  As WA0WHE states, "by using a helical configuration, the overall antenna height is reduced, thus eliminating the need for guying."  He continues by noting that "with the helically wound antenna, more equal current and voltage distribution is accomplished (as compared with a lumped impedance from a loading coil)."  In fact, the elongated coil is the antenna.

The are some tradeoffs with this antenna:  narrow bandwidth and the requirement for an effective radial system.  Even though my yard lacked space, I managed to squeeze in a number of non-resonant radials for the helix.

Here is the materials list for the 80 meter helix:

A 33-foot (10.06 meters) telescoping fiberglass mast.  I had a spare MFJ mast for this project.

Enough #14 AWG housewire for the helix.  Using the general dipole formula for a half-wavelength antenna, 468/f (MHz)=L(ft), and the chosen frequency of 3.750 MHz, I calculated a total wire length of 124.8 ft/38.04 meters.

A five-foot/1.52 meter wooden stake to support the lightweight fiberglass mast.  I have a homemade pivot system to lower the mast when I'm done for the day.  DX Engineering offers a professional metal pivot system at a modest price.

An 8-foot/2.43 meter copper ground rod at the base of the mast.  The radial system would be connected to the ground rod.

A Budwig HQ-1 coax connector.  The + lead would be attached to the vertical helix element, while the - lead would be attached to the copper ground rod with some copper braid.  The radial wires would be attached to the copper ground rod.

Four 62 ft/18.90 meters radial wires.  I used some #22 gauge wire for this part of the antenna.  More wire will be added later.  I used four radial wires to test the antenna system.

A 4-foot/1.21 meters antenna "stinger" from an old mobile antenna.  The metal whip would serve as a "top hat" for the helix.

Twenty-five feet/7.62 meters) of RG-8U coaxial cable with UHF connectors on both ends.

Vinyl electrical tape and nylon ties to secure the helix to the mast.

A clip lead to attach the helix to the top-loading "stinger".

An antenna transmatch to take care of possible mismatches in the antenna system.  My old Drake MN-4 was available.

Station equipment, including a transmatch, low pass filter, dummy load, and my faithful Swan 100 MX.

MAKING THE ANTENNA:

I built the helix on the ground.  With a chosen frequency of 3.750 MHz and 124.8 feet/38.04 meters of #14 AWG available, I began winding the helix on the MFJ fiberglass mast.  I used vinyl electrical tape to secure the coil as I proceeded up the mast.  At the top of the mast, I used a clip lead to attach the antenna to the "stinger."  That connection was covered with clear fingernail polish and several layers of vinyl electrical tape.

The bottom of the helix was soldered to the + lead of the Budwig connector.  The - lead of the Budwig connector was soldered to a small piece of copper braid.  The braid was then soldered to the copper ground post.

Each radial was in turn soldered to the copper ground rod and spread out as evenly as I could.  Because my backyard is fairly small, I had to adjust the position of each radial to conform to the "lay of the land".  Not all radials were straight--some were bent to pass through the garden along the edge of my property, while others ran under the house (my house is built on a post and pier system) and over to the driveway.  The last step in the process was attaching the clip lead from the helix to the top-loading "stinger."

It only takes a few minutes tor wrap up the radials when it comes to mowing the lawn.  Later on, I will use my pizza cutter to entrench the radials into the lawn.

Once everything was attached and protected from the weather, I hoisted the mast onto its wooden support stake.  No guy lines were needed.  I will add some later this week to give the mast more stability.

INITIAL RESULTS:

With the Drake MN-4 in line, I was able to keep the swr below 1.5 to 1 from 3.725 MHz to 3.775 MHz.  The bandwidth is quite narrow, but, with careful tuning, I could use most of the 80 meter band without surpassing a SWR of 2.3 to 1.

Much remains to be done with this shortened helical vertical.  As the late Jerry Sevick (W2FMI) suggests, improvement in the ground radial system will help performance.  Four decades ago, Sevick conducted a series of experiments with shortened verticals on 40-meters and demonstrated that short verticals can produce excellent results with a large number of radials and some "top loading".

I've made some good contacts on 80-meters, despite the noisy conditions found in the summer time.  Although local contacts can be made, the vertical helix does a much better job on DX.  In the past, I've used low-mounted dipoles to cover Hawaii on 80-meters.  That tradition will probably continue.  But for now, the vertical helix and its soon-to-be-improved radial system will give me many hours of fun on 80 meters.  I may even feed the "beast" with 450-ohm ladder line and a 4:1 balun to see what happens.

When I finished working through a few contacts, I disconnected the feed line and lowered the mast.

With every project, one learns a little more about about antennas and the skills necessary to communicate with our fellow amateurs around the world.

REFERENCES:

Ellingson, Gary L (WA0WHE).  "A Helically Wound Vertical Antenna for the 75-Meter Band."  Contained in the ARRL Antenna Anthology.  ARRL. Newington, CT. 06111.  Copyright 1978. pp. 20-21.

The ARRL Antenna Book.  14th Edition.  ARRL.  Newington, CT. 06111.  Copyright 1982. pp.10-11 and 10-12.

Sevick, Jerry (W2FMI) (SK).  "The Ground-Image Vertical Antenna/The W2FMI Ground-Mounted Short Vertical."  Contained in the ARRL Antenna Anthology.  ARRL.  Newington, CT. 06111.  Copyright 1978.  pp. 22-29.

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

To find the latest Amateur Radio news, visit my news site--http://kh6jrm.com.  I've included a few headline stories at the bottom of this post.

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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

Tuesday, July 9, 2013

A modified 20 meter extended double zepp antenna. Post #210

How would you like to boost your 20 meter signal by 3 dB with only 84.5 feet/25.76 meters of wire, two supporting masts, some 450-ohm ladder line, ordinary 50-ohm coaxial cable, and a few miscellaneous parts?

Today, I ran across a fascinating article by Paul E. Fuller (N8ITF), who designed a simple data sheet to help you build what is called "an extended double zepp antenna."  The double extended zepp is a dipole type of antenna consisting of two collinear 0.64 wavelength elements fed in phase, providing approximately 3 dB gain over a dipole on its intended frequency.  By following Fuller's advice, you can build an antenna that will give you some gain and more DX in the process.

Although my backyard is a bit cramped, there are numerous tall Norfolk Pine trees in an adjacent lot which could serve as a temporary support system for the 20 meter extended double zepp antenna.

With Fuller's article in mind, plus a few other ideas from several amateur radio operators, I set out to build this intriguing antenna.

MATERIALS:

Using Fuller's data table, I measured out two dipole elements, each segment being 42.25 feet/12.88 meters long.  I used #14 AWG housewire for the antenna elements.

Two supports for the antenna.  I had a 31 foot/9.53 meters jackite pvc mast already in place (it was supporting a 40 meter inverted vee) and found a nearby Norfolk Pine tree with a suitable branch at the 35 foot/10.67 meters) level. The horizontal portion of the antenna system would not be perfectly level, but, for my purposes, the available supports would do nicely.

A 4:1 current balun on the end of a 450-ohm ladder line stub.  Fuller says the 4:1 current balun should be capable of handling "at least twice the operating voltage to prevent  the balun from burning up for the swr mismatch on frequencies other than what the antenna was designed for."

For 20 meters, Fuller recommends a 450-ohm ladder line stub of 7.25 feet/2.21 meters.  For other bands, the length of the ladder line stub can be found by using the general formula 103/desired frequency in megahertz.

A convenient length of 50-ohm coaxial cable.  I had 75 feet of RG-8X with UHF connectors on both ends in the storage room.

An antenna transmatch, just in case.  I decided to use my trusty Drake MN-4 to take care of mismatches in the antenna system.

A suitable transceiver.  In my case, I used my qrp rig--the 1970s vintage Yaesu FT-7.  The rig would be run off solar charged deep cycle marine batteries.

ASSEMBLY:

Construction of the antenna was fairly simple.

I used a slingshot, fishing line, and a small "sinker" to launch one antenna element into the tree branch, which was 35 feet/10.67 meters) above ground.  Once I knew there was enough line to pull one dipole segment up to the tree, I lowered that element to ground level.

I lowered the jackite pvc mast to the ground.  With both antenna segments on the ground, I soldered the 450-ohm ladder line stub to each antenna segment.  Each connection was covered with clear fingernail polish and several layers of vinyl electrical tape.

A 4:1 current balun was attached to the ladder line stub.  The 75 foot/22.86 meter piece of RG-8X was connected to the 4:1 balun.

I first hoisted the jackite mast onto its mounting stake.  I then pulled on the fishing line to raise the remaining antenna element to its full height (between 30 feet/9.14 meters and 35 feet/10.67 meters).  The fishing line was tied off at a nearby wooden post. Ceramic insulators were used to keep the antenna elements separated from the pvc mast and the tree.   I left a little slack in the line to accommodate the wind and the swaying of the tree.

The coaxial cable was run into the shack through a plexiglass panel in the window frame of the shack.

Without the Drake MN-4 in the antenna system, my initial swr on 20 meters measured 1.6 to 1--not too bad.  I decided to leave the Drake MN-4 in the system in case I wanted to operate on other bands.  The old Drake transmatch kept the swr below 1.3 to 1 on 20 meters.  I will have to adjust the element lengths a bit to get a better swr, but, for now, I'm satisfied the antenna works.  My first few SSB reports in the late afternoon ranged between 56 and 59 with the little Yaesu FT-7 running around 10 watts output.

I briefly tried the antenna on 15 and 10 meters.  The tuning was a bit tricky, but I could get contacts without stressing the transmatch or the Yaesu FT-7. Rather than risk ruining the old rig or damaging the Drake MN-4, I decided to keep this antenna strictly for 20 meters.

The 20 meter extended double zepp was an enjoyable project that gave my qrp signal a needed boost.

REFERENCES:

http://myplace.frontier.com/~nb6z/nb6zep/htm.
http://home.comcast.net/~n8itf/doublezepp.htm.
http://www.rogerwendell.com/mystation.html.
http://qsl.net/4/..../ANTENNAS/40-thru-10-meter-zepp-Antenna.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, visit my news site--http://kh6jrm.com.  I've included a few headline stories at the bottom of this post.

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM)

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






Sunday, July 7, 2013

A simple 80 meter inverted "L" antenna. Post #209

Because my back yard is rather small, I haven't been able to erect a decent 80 meter dipole antenna.  In the past, I've used an inverted vee with elements measuring 67 feet/20.42 meters on a side.  Although the antenna worked reasonably well, it barely fit in back of my house and was clearly visible to my neighbors.  Another approach was needed.

I decided to build an inverted "L" antenna, since I had some room to go up (vertical) and some room to go horizontal (flat top segment).  If I used a lightweight wire (#20 or #22 gauge wire) and placed a mast among some trees bordering my lot, I could have a working 80 meter antenna with some degree of stealth.

An inverted "L" is a form of bent vertical, with the vertical section running up a mast for 1/8 wavelength (or more, if possible) and a horizontal wire running for 1/8 wavelength from the top of the mast.  Like all verticals, I would need a ground radial system to maximize efficiency and cut losses.

Although I could feed the antenna with 50-ohm coaxial cable, I decided to use 450-ohm ladder line in conjunction with a 4:1 balun and an antenna transmatch to operate on 80, 40, 20, 15, and 10 meters.

MATERIALS:

Using the general formula, 234/f (MHz)=L (feet), and the chosen frequency of 3.500 MHz, I cut 67 feet/20.42 meters of #22 AWG wire for the length of the 80 meter bent vertical.  The actual length was 66.85 feet/20.38 meters, but I rounded off the length to 67 feet/20.42 meters.

A slingshot, fishing line, and a sinker to launch the horizontal portion of the antenna into a tree notch approximately 30 feet/9.14 meters above ground.

A 33 foot/10.06 meters telescoping fiberglass mast (MFJ brand).   This mast would support the vertical portion of the inverted "L".

Six ceramic insulators to secure radial wires, the horizontal wire to the tree, and an insulator at the tip of the mast to route the remaining wire down the mast.

Four, 7 foot/2.13 meter wooden stakes to support a rudimentary radial system.

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

Four, 30 foot/9.14meters pieces of #22 AWG wire for the radial system.  These rudimentary radials are not a resonant 1/4 wavelength, because my lot is not large enough to accommodate a full 67 foot/20.42 meters radial in any direction.  As it was, I had to "snake" and bend the 30 foot/9.14 meters radial wires through the garden and along the border of my property.  My space is a bit restricted.

Fifty feet/15.24 meters of 450-ohm ladder line, a 4:1 balun, and an antenna transmatch (Drake MN-4).

Twenty five feet/7.62 meters of RG-8X to run from the 4:1 balun to the Drake MN-4 in the shack.

Small patch cords to connect the antenna transmatch to the rig (Swan 100-MX, the low pass filter, and the dummy load.

Nylon ties, vinyl electrical tape, soldering kit.

Log, note paper, pencil, J-38 key, and a Shure 444 microphone.

ASSEMBLY:

I first launched the antenna element into a convenient branch of a Norfolk Pine Tree bordering the south end of my lot.  The slingshot, fishing line, and sinker made the launch fairly easy.  I tied off the fishing line to an old fence post near the tree.

I then threaded the antenna line through the insulator at the top of the mast.  The insulator was secured to the mast by several nylon ties.  The horizontal portion of the antenna was 37 feet/11.28 meters.

The remaining portion of the antenna, 30 feet/9.14 meters, was secured by nylon ties to the mast.  That segment would be the vertical portion of the antenna.  The end of the antenna was 3 feet/.91 meters above ground.

The mast was hoisted onto its support stake.

One wire of the 450-ohm ladder line was soldered to the vertical portion of the antenna, while the other was soldered to four, 30 foot/9.14 meter elevated radials.  The radials were approximately 3 feet/.91 meters above ground.  One  radial was placed along the path of a east-facing garden and another was laid along the south-facing border of my property line.  One radial led into an abandoned lot bordering my property.  The fourth radial ran along side a pvc water pipe near the north facing side of my house.

Once the antenna was raised, it had a horizontal component of 37 feet/11.28 meters and a vertical component of 30 feet (9.14 meters).

INITIAL RESULTS:

For a compromised antenna system, it performed as well as my 80 meter inverted vee.  Although the radial system is far from ideal, the inverted "L" has been able to gather both local and DX contacts on 80, 40, 20, 15, and 10 meters.  With the help of the 4:1 balun, the 450-ohm ladder line, and the trusty Drake MN-4 antenna transmatch, I've been able to keep SWR on all bands below 1.7 to 1.  Antenna tuning is a bit challenging at times, but I can use 80, 40, 20, 15, and 10 meters without much difficulty.  Obviously, the radial system must be improved. But, for now, I'm enjoying the late night "adventure" on 80 meters.

REFERENCES:

http://www.hamuniverse.com/slopinginvl.htm.
http://www.hamuniverse.com/w7lpninvertedl8010.html.
http://www.youtube.com/watch?v=uuD2mBZKHO9.
http://www.dxzone.com/dx16525/allband-inverted-l-antenna.html.
http://www.amateur-radio-wiki.net/index.php?title=Inverted-L_antenna.
http://www.praisescribe.com/InvLAnt.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, visit my news site, http://kh6jrm.com.  I've listed a few headline stories at the end of this post.

Thanks for being with us today!

Aloha es 73 de Russ (KH6JRM).

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






Thursday, July 4, 2013

Antenna Topics: A simple 30 meter vertical antenna

Every now and then I feel the need to get away from the crowded amateur radio bands and just relax with an easy-paced conversation on 30 meters.  The band, which stretches from 10.1 MHz to 10.150 MHz, is quite narrow and is restricted to cw and data transmissions.

The pace of communications is generally more relaxed on 30 meters than in any other amateur radio band.  And since I need more practice in cw, this band is perfect for sharpening my skills.  Along the way I also meet some interesting and helpful people.

In order to use 30 meters, I have to change rigs.  My old Swan 100 MX, Yaesu FT-7, and Kenwood TS-520 don't cover this band, so I rely on another excellent transceiver--the Ten Tec Argosy II.  This rig can run up to 50 watts output, but I prefer the 5 watt setting for most of my cw work.  I can run the Argosy II off my solar charged deep cycle marine battery all day without depleting the battery.

Although I could use my 40-10 meter inverted vee fed by 450-ohm ladder line, I decided to build an inverted vee especially designed for 30 meters.

So, last Friday morning, I used a halyard/pulley combination to lower the 40 meter inverted vee.  I removed the antenna and its Budwig HQ-1 center connector and placed them in a plastic storage bin.

MATERIALS:

One 33-foot (10.06 meters) MFJ telescoping fiberglass mast.  That was already in place.

Two, 7-foot (2.13 meters) tie off stakes.  These were already in place.

A 50-foot (15.24 meters) of RG-8X coax with UHF connectors.  The cable was in the shack.

Two ceramic insulators from the junk box...one insulator would be attached to each element of the inverted vee dipole.

One Budwig HQ-1 center connector.  I had an extra connector in the junk box.

Fifty-feet (15.24 meters) of #18 AWG speaker wire.  I had some of this wire in the shack.  For a permanent  installation, I would recommend stronger wire, such as #14 AWG house wire.

A halyard/pulley system to hoist the vee into position.  I had the system already attached to the fiberglass mast.

ASSEMBLY:

The antenna was built on the ground.  The halyard/pulley system would later hoist the antenna into position.

Using the general formula 468/f (MHz)=L (ft),  I cut the antenna to a length of 47 feet (14.32 meters).  The computed length was 46.33 feet (14.12 meters), but I used the longer length to accommodate for adjustments to the dipole elements.  The dipole was divided into two equal parts--each 23.5-feet (7.16 meters) long.

Each dipole element was attached to a ceramic end insulator.  The top portion of each element was soldered to the Budwig HQ-1 center connector.  Connections were covered by several layers of vinyl electrical tape.

Before I attached the RG-8X coaxial feed line, I wound the top portion of the coax into a 6 turn RF choke to keep RF off the cable.  The coil diameter was 6-inches (15.24 cm).

I attached the coax feed line to the center connector and hoisted the inverted vee into position with the halyard/pulley arrangement.

I tied off the dipole elements to the support stakes.

I ran the cable into the shack through a nearby window and attached the feed line to the Drake MN-4 antenna transmatch.  Small patch cords linked the Drake MN-4 to the low pass filter, dummy load, and the Ten Tec Argosy II.

PRELIMINARY RESULTS:

Without the Drake MN-4 in line, the SWR measured 1.7 to 1--not bad for a hurried half hour of building.  A bit of trimming would come later.  The Drake MN-4 brought the SWR down to 1.1 to 1 without a problem.

So far, contacts have been excellent in the late afternoon hours, with reports ranging from 569 to 589 with the Argosy II running 5 watts.

I had fun making this unsophisticated, but  efficient antenna.  Best of all, I didn't spend any money making the antenna, thanks to my junk box in the garage.  Thirty meters is a fun band with lots of helpful people.  So, get  out your key or keyer and try 30 meters.  This band is quickly becoming my favorite place to catch a good "ragchew".

REFERENCES:

http://www.wm8c.com/60-minute-dipole.htm.
http://www.kd5om.com/build-an-inverted vee.htm.
http://www.youtube/watch?v=fyOWRTWdDKM.
http://www.146970.com/PDFs/Antenna-HFAntennasforbeginners30MetersandBelow.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 headlines, check out my news blog--http://kh6jrm.com.  I've included several stories at the bottom of this post.

Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).

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


Tuesday, July 2, 2013

Antenna Topics: Disconnecting equipment for safety. Post # 207

Like many regions of the northern hemisphere summer has come to Hawaii Island.  Although this tropic paradise is known for its gentle climate, there are occasions where severe thunderstorms and lightning plague Hawaiian hams just like our fellow amateur radio operators on the U.S. Mainland.  Every now and then, a small sea-spawned tornado (waterspout) comes ashore in Kailua-Kona and does some minor damage to beach areas.  Most of these unwanted guests arrive on the strong winds of a frontal passage which begins north of Kauai and runs down the island chain to Hawaii Island.  While most of these severe storms occur during the winter months, it's not unusual for a bad thunderstorm to strike in mid-summer and cause damage to utility poles, transformers, and other electrical equipment.

Now that I'm mostly retired, I tend to stay at home and can keep watch on the weather. With adequate warning, I can safely disconnect  my antennas and get my rigs out of danger before any storm strikes.
 With the passing of time, I've tended to get lazy about protecting my equipment, especially if my xyl and I decide to go on an impromptu shopping trip or to visit friends across the island.  I've been careless in the safety department--a pattern I've vowed to break ever since I read a helpful article by Claudia J. Lang (KC3GO) called "Quick power and antenna disconnects for equipment lightning safety."  The original article was published in the 13th Edition of "Hints & Kinks for the Radio Amateur."

Following Ms. Lang's example, I've instituted a storm safety program for my amateur radio equipment.  I follow this routine everyday, whether I'm away from the house all day or just visiting friends down the road.


1. When I finish operating for the day, I unplug all transceivers and computers from the power mains.  Most of my rigs run off solar-charged batteries, so I just disconnect all power leads from the deep cycle marine battery and put the solar panels in the garage.  I also disconnect my telephone line, since the line is also used for internet access.

2.  All antennas are disconnected and grounded at the mast for my verticals and inverted vees.  I also disconnect the feed line from my under the house 40 meter loop.  I also disconnect the RG-8X coaxial cable leading to the 4:1 balun on the garage wall.  I use home made swivels to lower the vertical and inverted vee antennas to ground level.

3.  I make sure all power cords have surge suppressors, so I don't get a surprise when I plug equipment back into the ac mains.

As good as these steps may be, "Hints & Kinks" Editor David Newkirk (WJ1Z) recommends some additional precautions to protect your equipment:

"Disconnecting antenna and ac-power leads may not fully protect gear connected to ground.  The best way to protect station electronic equipment against lightning damage is to disconnect all wires from the equipment and move the equipment away from station wires and cables."

Newkirk also suggests that you "keep a weather eye out and disconnect your gear well before severe weather moves into your area...better yet, keep it disconnected whenever you're not using it."

I apply these same rules to my audio and television equipment.  Whenever I leave the house, I disconnect all power and speaker leads from my component stereo system and make sure the television set is disconnected from the ac mains and the roof-mounted antenna.  Like my amateur radio equipment, my entertainment systems use surge protectors as added protection from power line "spikes."

Hopefully, these simple tips will save your equipment when lightning threatens your area.

REFERENCES:

Lang, Claudia J. (KC3GO).  "Quick Power and Antenna Disconnects for equipment lightning safety."  Contained in "Hinks & Kinks for the Radio Amateur", 13th Edition.  ARRL.  Newington, CT, 06111.  p. 9-7.

Editorial comments from David Newkirk (WJ1Z).  Contained in "Hinks & Kinks for the Radio Amateur", 13th Edition. ARRL. Newington, CT, 06111. p. 9-7.

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, visit my news site--http://kh6jrm.com.  I've included a few headline stories at the bottom of this post.

Thanks for joining me today!

Aloha es 73 de Russ (KH6JRM).

BK29jz15--along the beautiful Hamakua Coast of Hawaii Island.