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Showing posts from July, 2012

Simple Antennas for Amateur Radio Operators--a continuing series

KH6JRM's Amateur Radio Blog

Post #177

A modified fan dipole

How would you like to make a simple, stealthy, and inexpensive antenna that covers 80 to 10 meters?  All you need is a local hardware store, some connectors, some RG-8 coax, schedule 40 pvc pipe, some copper plumbing straps, a few bungie cords, and about 250-feet of stranded copper wire.

The details of this fascinating skyhook can be found in the 31 July 2012 edition of eham.net (http://www.eham.net).  Howard Gorman, W6HDG, has writen an article entitled "The Fence Fan Dipole (FFD)--A Quick, Easy, and Inexpensive Multiband Antenna."

Howard provides detailed instructions and photographs to guide you in completing this project.  Most of the materials for his antenna came from a local Home Depot store.  Howard used a 12-foot fence around an old tennis court to support a 10-foot schedule 40 pvc pipe and ran antenna elements from a special antenna connector atop the pvc pipe.  He used bungee cords to attach the elements f…

Simple Antennas for Amateur Radio Operators--a continuing series

KH6JRM's Amateur Radio Blog

Post #176

A compact 40-meter vertical

There are times when a small vertical comes in handy.  You could be in a space restricted environment such as I where neighbors are almost back to back or you could be looking for an easily portable antenna useful for mini-DXpeditions or a casual day of operating from a park or beach.  There is a solution to this often vexing problem.

If you have the resources, you may want to consider screwdriver antennas, adaptations of various mobile antennas (ham stick), or event the handy Buddipole sytem.  But if you're on a restricted budget and willing to "roll your own", you can find all the materials you need at the nearest hardware store.

What I wanted to build was as a top-loaded "vertical helix" that could be erected in my backyard and easily hidden by bushes and trees bordering my qth.  Based on various readings in antenna literature, I found that if you wound a half-wave length of ordinary AWG #22 ga…

Simple Antennas for Amateur Radio Operators--a continuing series.

KH6JRM's Amateur Radio Blog

Post #175

A "long wire" antenna

One of the joys of being an amateur radio operator is the creation of antennas.  Since I live on a restricted lot surrounded by neighbors and high power distribution lines from the local utility, I have to be creative if I want to get on the air.  Like many of you, I've had to live with compromise antennas most of my amateur "career".  Sometimes, opportunities come along that just beg for experimentation. 

Such was the case today, when several of my neighbors mentioned they would be visiting relatives for several days.  Since my teaching assignments won't begin until 01 August (or later, if you are a substitute teacher such as I), I offered to keep on eye on their homes until they returned.

Goody!  There are several 30 to 50-foot trees in back of my house on my neighbor's property that just call out for antenna use.  Oh, well, that must be my imagination.  Anyway, I decided to string up a full-…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog

Post #174

Antennas and Contests

Amateur Radio Operators will have a lot to do during August.  In the August 2012 edition of "QST", there are at least 33 contests hams can enter.  These contests range from weekly sprints to the ARRL 10 GHz and up Contest.  There is something for everybody in August, even if you aren't an active contester.  I try to jump in on a few contests (mainly cw and SSB) to see just how good by homebrew antennas work.  Sometimes, my great antenna ideas fall flat--they just don't perform the way I want them too.  As always, contests give us antenna experimenters plenty of "rope to hang ourselves."

Now that I've installed my garage roof 20-meter loop, I'm anxious to see how this skyhook performs. If performance is not up to expectations, I'll opt for the 40 to 10 meter inverted vee in the back yard.  That antenna has always done well, propagation permitting, of course.

Among my selected targets will…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog

Post #173

Friends remembered and a 40-meter vertical for restricted space

This has been a sad week for many amateur radio operators on the Big Island of Hawaii.  Two well-known hams have died and will be missed in our small radio community.

First, Paul Lieb, KH6HME, passed away last week in California.  Paul was best known for his VHF, UHF, and SHF beacons atop Mauna Loa on the Island of Hawaii.  When the tropo was in or a rare ducting across the Pacific Ocean and the U.S. mainland occurred, Paul was on top of the 13,000-foot mountain handling a wave of contacts.  Paul was a friendly guy who always was available to help his community and the Big Island Amateur Radio Club.

Second, Joe Day, NH7LP, died this past Saturday morning following his daily swim in Hilo.  Although he was not too active on the bands, he was always willing to talk "radio" and help others with their licensing efforts.  He remained active on echolink, since he was unable to erect…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog

Post #172

A homebrew 20-meter loop

For the better part of two days (Saturday and Sunday), conditions on 20-meters from the Laupahoehoe qth have been poor.  Apparently, a near class X solar flare from our sun has made severe inroads on HF propagation.  So, once my xyl and yours truly finished our daily routines, I decided to work on my modest "antenna farm" in the backyard.

Although my hastily-built 20-meter delta loop worked fine, it was low enough to cause problems with neighborhood pets, wild pigs (we have many here), assorted birds, and other furry creatures (feral cats, goats, and even a lost cow or two).  Living in an agriculture zone does present certain problems.

I took down the delta loop and looked around for an alternative location--not an easy task on a small lot.  While I was creating my replacement antenna scheme, I glanced at my wooden garage.  It measured 17-feet by 16-feet, if I included the laundry room.  Aha! Why not draft the wo…

Simple Antennas for the Amateur Radio Operator--a continuing series.

KH6JRM's Amateur Radio Blog

Post #171

ANOTHER APARTMENT ANTENNA

Thanks to some good weather today, I was able to get out of the house and work on my modest antenna farm in the backyard.  In my last post, I described a hastily built 20-meter delta loop fed by RG-6 coax.  The loop is working fine and I plan to keep it up for awhile.  Later, I will connect the loop to my station with 450-ohm ladder line, so I can use the antenna for 15 and 10 meters.

After that small antenna project, I was once again on the lookout for other simple antennas that even I could build.  It's true...I'm not the sharpest tool in the shed when it comes to building things, but I do better with each new project.  My fingers have solder burns to prove it!   Anyway, I wanted to improve my emergency indoor antenna without creating problems with RF emissions or TVI.  As I was searching antennas through the internet, I came across an article by Zachary Flemming entitled "How to make an indoor random ante…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog

Post # 170

A Simple 20-meter loop antenna

I've always had a fascination with full-wave loop antennas for the amateur radio bands.  While loops take up a lot of space, they are easy to make and generally quieter antennas than verticals.  Most of the materials for loop antennas can be found at your nearest hardware store or in your garage.  If you're a radio packrat such as I, you probably have extra wire and coax stashed somewhere near your shack. 

While there was a break in the rain showers that have soaked Hawaii Island for the past few days, I ventured into my flooded backyard to examine my antennas for signs of damage or loose connections.  Apparently, a tree branch struck the 20-meter vertical dipole in back of the garage, necessitating lowering of the fiberglass mast and the removal of the wire elements.  I decided to restring the 20-meter antenna as a full-wave loop fed by approximately 40 feet of RG-6 coax.  I cut three, 23-foot lengths of A…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog

Post #169

NOVICE ANTENNAS

The remnants of Hurricane Emilia are sweeping Hawaii Island with frequent showers and gusty winds--not the sort of weather conditions I prefer to do antenna maintenance.  So, bowing respectfully to the wiles of Mother Nature, I continued my antenna research via my personal library and notes from years past.

One of my favorite amateur radio magazines besides Radcom (RSGB), QST, and CQ is the quarterly volume issued by the Quarter Century Wireless Association (QCWA Journal).  The magazine features interesting articles about hams who have been licensed 25 years or more and have contributed to the "radio art" in both their professional and personal lives.  The current issue (Summer 2012, Volume 61, Number 2) has several intriguing articles articles including a review of the venerable Barker & Williamson 6100 SSB, AM, and CW 80-10 Meter Transmitter and a continuing series of articles on Amateur Radio Novice Operator histor…

Simple Antennas for Amateur Radio Operators--a continuing series

KH6JRM's Amateur Radio Blog

Post 167

A MINI-EXPEDITION

I've always wanted to go on one of those heavily funded DX-peditions to some exotic place and be on the receiving end of a DX pileup. I'm sure I could enjoy myself, even after days of stress, QRM, and unforeseen operating problems in some isolated locale.  For now, those fantasies will be explored in the pages of QST or CQ until I become sufficiently rich to afford such a trip.

Meanwhile, many amateur radio operators (including yours truly) will try to live life as it comes and operate whenever circumstances permit.  Such was the case over the past weekend, when I did my regular assignment of being the tower announcer at the monthly drag races held by the Big Island Auto Club.  Unlike past weekend stints at the Hilo Drag Strip, I brought along my HF "Go Kit" and decided to operate at the track before and after the regular races were run.  Since I arrive very early on Saturday and Sunday morning (0500 local time),…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog

Post 167

INTRIGUING ANTENNAS

Hawaii Island dodged a potentially wet weekend with the passing of tropical depression "Daniel" Thursday evening.  The island is receiving some high surf and a few heavy showers, but that's about all the storm could do.  "Emilia" is still churnging about about 1000 miles to our east, but, it too, is predicted to track south of Hawaii Island.  The hightened alert gave amateur radio operators here a chance to check out their emergency "go" kits and review their own procedures for such continguencies.

While I waited for the bad weather to pass, I found three articles in the 13 July 2012 edition of "e-ham.net" that could provide antenna ideas.

For those amateurs involved in emergency communications, a good NVIS (near vertical incident skywave) antenna is a must for regional HF  operations out to about 300 miles.  Pat Lambert, W0IPI, has published an excellent tutorial on NVIS antennas which…

Simple Antennas for Amateur Radio Operators--a continuing series

KH6JRM's Amateur Radio Blog
Post 166

EMERGENCY ANTENNAS

Hurricane season has arrived in the Hawaiian Islands and local civil defense officials are encouraging local residents to prepare for some rough seasonal storms.  In the Central Pacific, hurricane season runs from June to November.  Presently, there are two storms which will impact Hawaii Island--Daniel, now a very wet tropical depression, and Hurricane Emelia, located about 2,000 miles east of Hawaii Island.  Although the storms are predicted to weaken as they pass below Hawaii Island, they will bring heavier than normal rain, gusty winds, and storm surf ranging up to 10 feet in some lowland areas.  This is a challenging time for surfers, who have been warned to stay clear of rough spots, and for local residents, who could lose power and suffer building damage.

With the exception of Hurricane Iniki in 1992 and Hurricane Ewa in 1982, Hawaii has been spared the full force of seasonal hurricanes thanks to the storms entering cooler…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog
Post 165


BACK TO BASICS


One of the creative things amateur radio operators can do these days is to build simple, effect wire antennas.  Although most commercial antennas are well made and perform well, there is nothing quite like building your own antenna and working DX on a shoestring budget.  So, let's begin with my favorite band--20 meters.


After I took down my temporary "long wire" antenna this morning, it was time to rebuild a 20-meter antenna that had seen better days.  As mentioned in post 164, rodents and other unnamed creatures chewed on my feed lines and elements, creating an ugly mess.  Fortunately, I still had a homebrew 33-foot mast made from 2-inch pvc pipe which could be pressed into service.  I attached 16 1/2 feet of AWG 22 wire to one half of the mast and another 16 1/2 feet of wire to the bottom of the mast.  At the midway point of the mast, I attached and soldered 40-feet of 450-ohm ladder line.  The line ran into a 4:1 bal…

Simple Antennas for the Amateur Radio Operator--a continuing series

KH6JRM's Amateur Radio Blog
Post 164

A QUICKLY DEPLOYED "LONG WIRE" ANTENNA

Most of my weekend chores are done, which gives me a few hours to play with antennas before Monday arrives.  Yes, even for those of us in the "semi-retired" category, there are things to do before the warm glow of vacuum tubes draws us back to the rf circus.

I've been able to build and test numerous antenna designs over the past few weeks, thanks to a break from my substitute teaching duties.  My xyl and I expect to be called shortly for another assignment since Hawaii public schools begin during the first week of August.  So, there's lots to do--clean up the "shack", inventory equipment, and otherwise try to find stuff I misplaced over the year. 

As for antennas, I decided to take down the inverted 40-meter vee for maintenance.  Rats and other small animals have chewed up some of the wire elements and a piece of coax I used to connect the 4:1 balun to the Drake MN-4 tune…
KH6JRM's Amateur Radio Blog, post 163

An emergency 6-meter antenna

Although 6-meter openings to Hawaii are fairly rare, many of us amateurs on Hawaii Island look forward to times when the "magic band" is open.  As is often the case, when 6-meters and 2-meters "open up" to the U.S. mainland, amateurs in the central Pacific often don't have a decent 6-meter antenna available when propagation is favorable.  By the time  I get home to tune in the 6-meter signals, most of the action has already past and many signals have disappeared into the noise.  Such is the state of the ionosphere.

However, I think there is a way to keep on top of 6-meters without an outlay of additional funds.  Of course, it helps to have a rig that can cover 6 - meters--most of the current HF  rigs from Kenwood, Yaesu, Icom, and Alinco cover the band.  Or in my case, I can resort to an old Heathkit 6-meter rig in the storage room for such emergencies.

As for antennas, you may have a workable 6…

Mobile operations on Independence Day

KH6JRM's Amateur Radio Blog, post 162

Topic:  Mobile operations on Independence Day

Happy 236th Birthday to the United States of America.  As is the custom in this country, the national holiday is reserved for barbecues, sporting events, parties, fireworks, and just kicking back and enjoying what we fought for over these past 2 1/4 centuries.  Those celebrating the holiday on Hawaii Island have some added attractions, such as classic car cruises, outrigger canoe races, parades, and special concerts of Hawaiian music.  This will turn out to be quite a noisy affair.  Everything should return to something close to "normal" on Thursday. 

This year, I'm getting away from all of the noise, heavy traffic, and crowded beaches to operate HF mobile and portable in my own neighborhood.  Over the past few weekends, I've been using my emergency mobile set up in the van to operate from highlands above my qth.  When the Laupahoehoe Sugar Company closed its doors in the mid-90s, t…

Simple Antennas for the Amateur Radio Operator

KH6JRM's Amateur Radio Blog

A simple 40 and 15 meter antenna you can build in just a few minutes

Sometimes it is possible to operate two or more bands with one antenna and a short run of good quality coaxial cable.  A simple 40 and 15 meter antenna, used either as a dipole or as an inverted vee, will provide hours of enjoyable contacts at modest power levels.

I've built several variants of this antenna, with the inverted vee configuration preferred because of my limited backyard space.  An antenna cut for 40 meter operation can be used on  15 meters because dipoles have harmonic resonances at odd multiples of their resonant frequencies.  Because 21 MHz is the third harmonic of 7 MHz, a simple 40 meter antenna (approximately 33 feet on each side of a center connector) can be used for both 15 and 40 meters.  There is one drawback to this wonderful plan.  The idea works if you cut the 40 meter dipole for use in the cw portion of the band, for example around 7.010 MHz.  As you move h…