Saturday, March 31, 2012

Simple Antennas for the Hawaii Island Amateur Radio Operator--a continuing series of personal observations

It's been awhile since I jotted down a few notes about antennas.  This is one of those cases where "one should be careful about what you wish for."  Until March, most of Hawaii Island was gripped in an extended drought which began 3 years ago.  Although West Hawaii (including Kailua-Kona) has been struggling with a prolonged dry spell for several years, those of us living on the windward usually received sufficient trade wind showers to stave off any water shortages.  Until March, many East Hawaii residents got by with diminished water supplies, hoping that the weather would change.  March has turned out to be quite wet on the windward side, with rain totals in Hilo exceeding 25 inches for the month.  All of this moisture was accompanied by strong 20 to 30 mph winds, mudslides along major highways, and several power outages.  As April Fool's Day approaches, the weather is improving and only scattered showers will herald the arrival of our spring season.

During the past few weeks, heavy rains and windswept branches have damaged most of my verticals (40-meter inverted vee and the 20-meter vertical dipole).  Fortunately, the 40-meter loop under my home served as an excellent emergency antenna, especially for monitoring local hf nets.  The loop pushes a good signal out to 300 miles or so, just enought to cover the islands from Hilo to Lihue, Kauai.  I will be restringing the wires on the vee and the vertical dipole--a task that will occupy a few days with my current teaching schedule.

Meanwhile, I've been able to erect a simple vertical that keeps me on the air.  I have a large tree on the border of my rental lot which serves as the terminus of a 135-foot "long wire" I shot over the tree with a slingshot.  The wire is attached to my Drake MN-4, with a counterpoise connection to the 40-meter loop under the house.  I also have the ground lug of the MN-4 connected to a small radial field in the yard (three, 33-foot radials laid out on the ground).  So far, this crude system works and I get no rf in the shack.  The efficiency of this "skyhook" is probably poor, but I do get out and I do get some moderate DX (Japan, Korea, Philippines, and sometimes Europe).  I can work 80 through 10 meters with 10-20 watts from the old Swan 100-MX (cw).  This "lashup" antenna will serve my immediate needs until the other verticals are rebuilt and erected.  Never a dull day at the radio ranch.

Have a good weekend!  It could be worse--I could be organized.

Aloha es 73 de KH6JRM
Laupahoehoe, Hawaii--BK29jx15.

Friday, March 23, 2012

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

I haven't been able to do much antenna maintenance because of a full-time class schedule at Laupahoehoe High and Elementary School.  My xyl and I have been substitute teachers for several months now and we manage to keep busy with students from kindergarten through 12th grade.  Most of my free times is on the weekends, so I try to squeeze in a little operating and station maintenance on Saturday and Sunday.  All of this makes for a full week.  I don't mind--the routine keeps me busy and frees me to do some creative work with students, especially those in special education.

Over this past weekend, I was tidying up the shack and monitoring 20-meters when I found two old antenna books that may prove of some use for you, especially if you are on a tight budget.  The first book is one of my modern "classics"--"Lew McCoy On Antennas.  Pull up a Chair and Learn from the Master."  This compact volume is still in print from CQ Communications, Inc.  The late Lew McCoy, W1ICP, writes in an easy style and makes technical data understandable for even the beginning amateur radio operator.  The book covers topics from transmatches to multielement antennas and feed-line radiation problems to the complexities of standing wave ratios.  McCoy makes the amateur radio operator comfortable and anticipates most of the questions any operator would have.  This book would be ideal for a new operator or for those who wish to brush up on basic antenna theory.

The second volume I found in the old radio bookcase was "Easy-Up Antennas for Radio Listeners and Hams" by the late Edward M. Noll, W3FQJ.  Noll's book is available from MFJ Enterprises, Inc.  The book is a comprehensive  handbook that contains key antenna designs, construction tips, techniques, and tools you need to build effective, inexpensive antennas that work and stay up.  Many of the illustrated designs (most with photographs) can be adapted for both shortwave listening and amateur radio use.  The book covers basic, do-it-yourself antennas for shortwave broadcast, FM broadcast, medium wave applications, long wave reception, VHF/UHF uses, and various ham radio antennas.  I've tried several of Noll's slopers, verticals, and horizontal loops and find that they work and are structurly strong.  As in the book by McCoy, the financial outlay for these antennas is modest--some of the basic materials, such as pvc pipe, light gauge wire, and basic tools you may already have in your garage or in your "junk box".  If you lack some of the materials described in either book, a trip to the nearest hardware store or home improvement outlet can supply you with most of the items you need for these simple, effective antennas.

There is no need to spend a lot of money on antennas if you can build them yourself.  I'm not criticizing the commercial antennas now on the market.  Most of them are effective, sturdy, and well-designed.  Once in awhile I get the chance to operate from a shack with a 3 or 4 element beam atop a 15-meter tower.  That can be quite an experience, especially if you succumb to the wonders of an Alpha amplifier.  There is nothing quite like breaking a pileup with a commanding signal.  However, once I return to the reality of my small lot, modest station, nearby power lines, and curious neighbors, I transform myself into "stealth mode" and the low visibility operator.  I've become accustomed to lowering my verticals during the day and running low power most of the time.  Despite this self-imposed limitation, I manage to enjoy the hobby and get immense satisfaction from "rolling my own" antennas.  The antennas I use aren't fancy, but they do work.  And most of all, they are cheap to build and maintain.  So, if you are into making your own skyhooks, the books by McCoy and Noll can give you an antenna building experience without the breaking the bank.

And truth be told, I really want to build a decent tower and run a 4-element beam on 20-meters.  But that dream will have to wait until the xyl and I build our new home.  We have enough land to erect a variety of antennas, and I hope to have that dream materialize in the future.  Meanwhile, I'll continue to read, experiment, and build.  All of this activity keeps me home, which makes the xyl happy.  Besides, as a semi-retired commercial radio guy, I can't stay away from rf very long before I sense something is missing.  I guess it's in the blood.  Besides, if you don't keep busy, your mind has a tendency to rust.  So, it's back to the soldering gun, connectors, and ladder line.  After that, it's time to work a few contacts, prepare lesson plans, and correct tests.  It could be worse--I could be organized!

Have a good weekend.

Aloha es 73 de KH6JRM--along the beautiful Hamakua Coast--BK29jx

Friday, March 9, 2012

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

Thanks to the recent CME and flares from the sun, my operating time was brief today.  Everyband was noisy and all I did was listen to a few strong signals on 20-meters.  I made a few calls, but with only 10 watts to the vertical dipole, I didn't work many people.  So, I spent the day cleaning and tightening my loop, 20- meter vertical dipole, and the inverted vee in the backyard.  When I finished with basic maintenance, I was once again on the prowl for interesting, homebrew antennas that even I could build.  One of my favorite antenna books is "Simple and Fun Antennas for Hams" published by the ARRL.  The book is loaded with real-world, practical antennas you can build yourself with a minimum of cost and time. 

I came across an interesting antenna that may appeal to those of us restricted by space and CC&Rs. Jeff Brone, WB2JNA, adapted a design by Robert Johns, W3JIP, which appeared in the August 1998 issue of "QST".  Jeff's article is found in chapter 12, pp. 7-8.  Basically, Jeff's project is a "Cheap and Dirty Multiband Antenna" using an end-loaded wire (with a coil) balanced by a counterpoise.  There are several commercial variations on this theme by MFJ and B & W.  Since the antenna is so simple to build, you may want to forego the commercial versions and "roll your own."  According to Jeff, all you need are 32 feet of #14 to #18 copper wire, with 20 feet bare in order for winding the loading coil; two  "dog-bone" end insulators; an empty two-liter soda bottle; two alligator clips; 32 feet of insulated wire, such as #16 or #18 speaker wire for the counterpoise; and coax to connect your rig to the antenna.

Measure and cut off around 13 feet of wire.  This will give you enough for a span of about 12 feet after you have secured each end of the wire to its insulators.  Wrap about 17 to 20 turns of bare wire on the soda bottle to make your coil.  Having done this a few times, I can say this is the hardest part of the project.  Be sure you leave enouogh space between the turns so that there is sufficient room for an alligator clip to fit without shorting to adjacent turns.  You can use tape, coil dope, silicone seal or whatever you like to hold the coils in place.  Take a length of coax (I happened to have some RG-6 with adaptors on hand) and solder an alligator clip to the center wire.  The length of the counterpoise attached to the shield of the coax will depend on the lowest band you intend to use.  Like Jeff, I used 32 feet for 40 meters.  Connect the center conductor's alligator clip to the coil, about 13 turns from the main radiating wire.  Run the 32 feet of counterpoise along the floor of your room or apartment.  Be sure to keep the end away from people and pets, because there is a large amount of rf at the end, even for QRP operations.  Connect the other end of the coax to your rig and transmit.  You may have to try different turns to get a good SWR.  To use the antenna on 20 meters, connect the alligator clip about 2 to 3 furns from the front of the coil.

You may want to cut the counterpoise about 16 feet in length and attach an alligator clip to its end for attaching the other 16 feet when you want to work 40 meters.  The antenna cost me nothing, since I had an empty diet Coke bottle, some insulators in the junk box, and about 100-feet of #18 speaker wire in the garage.  I was surprised how well this homebrew antenna worked.  You could even mount this on a wall of your operating position if you ran QRP levels of 10 watts or less.  This antenna will not perform like a beam or even a decent dipole in your yard, but it will get you on the air.  Of course, your success will vary--that's part of the fun of Amateur Radio.  Besides, if this antenna does work for you, you have saved some money and built something you can call your own.

Have a good weekend!

Aloha es 73 de KH6JRM--Laupahoehoe, Hawaii, BK29jx15.

Friday, March 2, 2012

Simple Antennas for Hawaii Island Amateur Radio Operators--a continuing series

It's been a busy week of teaching for me and my xyl at Laupahoehoe High and Elementary School.  As substitute teachers, we have a variety of assignments ranging from special education to agriculture.  Variety is the spice of life at this rural school on Hawaii Island.  Both of us enjoy doing something positive for our community in our "sunset years."  Now that the school week is over, I can focus my attention on amateur radio and my favorite aspect of the hobby--building antennas from commonly available materials.  A good, effective homebrew antenna is what you need to join the ARRL International Phone DX Contest, which begins 03 March 2012 at 0000 Z and ends 2400 Z on 04 March (this weekend).  I plan to do a lot of listening and get what contacts I can as a QRP station.

My limited contest participation will rely on the homebrew 20-meter vertical dipole in back of the garage and the trusty 40-meter inverted vee along the hedge line fronting my neighbor's house.  I plan to have fun no matter the condition of the atmosphere and the rising volume of qrm.  I'm sure my 10-watt signal will get a few contacts no matter how propagation goes.  So, I'll raise the verticals during operating hours and lower the antennas when I'm not calling "cq".  With rain and perhaps a few thunderstorms in the forecast, I'm glad I installed swivels to lower and raise antennas quickly.  This contest will test just how effective my "homebrew" antenna "farm" really is.  Fortunately, I have a good supply of RG-6 coax, #14 wire, connectors, and some 450-ohm ladder line in case strong tradewinds take any antenna to the ground.  As a last resort, I'll connect my Yaesu FT-7 or Swan 100-MX to my under-the-house 40-meter loop and see what I can stir up.

Speaking of antennas, you may want to peruse the March 2012 "QST", which focuses on antennas.  There is an interesting article by Joel Hallas, W1ZR, called "Selecting a Commercial HF Vertical for Your Station" on pages 69 and 70.  Although I prefer building my own verticals, Joel makes a strong case for a commercially produced vertical if your interests lie in that area.  Joel reviews a number of commercial verticals from Butternut, Gap, Hy-Gain, Force 12, SteppIR, New-Tronics (Hustler), and Mosley.  Any one of these products could be what you need to get on the air, especially for those with severe space limitations.  The only commercial vertical that I have tried, and that was years ago, was the Hy-Gain 12AVQ--a classic 1/4 wave trap monopole covering the 20, 15, and 10 meter bands.  At 13-feet, it is a compact antenna that can either be ground mounted or elevated.  I used the 12AVQ as a ground mounted vertical with 16 quarter-wave radials cut for 20-meters.  The antenna served me several years without problems until Hawaii's tropical air, volcanic haze, and heavy rains finally destroyed the aluminum and traps.  I may pick one up one of these 12AVQ skyhooks again just to see what I can do with it.  But for now, I'm content to "homebrew" what I need.  As you may have guessed, my favorite antenna store is Home Depot, Ace Hardware, or the nearest farm supply store.

Have a good weekend and enjoy the contest!

Tnx for stopping by.

Aloha es 73 de KH6JRM
Laupahoehoe, Hawaii--along the beautiful Hamakua Coast