Tuesday, July 31, 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 for each band.  The antennal elements also served as guy wires for the pvc pipe.  He fed the antenna with one piece of RG-8 coaxial cable.  Howard's station is modest--a Yaesu FT-857, an Astron 30-amp power supply, and an antenna tuner.

According to Howard, SWR readings for all bands except 15 meters showed SWR at 1.9 or less across each band.  Fifteen meters and portions of 75 meters could be used if an antenna tuner were used to reduce the SWR.

Howard acknowledges the limitations of his creation by noting, "I have no illusions about DX worthiness of this antenna.  The multiband variety of dipole...when well-tuned, should not suffer appreciably in performance over a monoband dipole at similar height.  The advantage of  a single feedline connot be overemphasized."

Despite the limitations of this antenna, it's worth a try, especially if you don't have much real estate to erect antennas.  Howard says the antenna is barely noticeable and blends in well with the environment--something to consider in crowded neighborhoods.  If you follow Howard's instructions and photographs, you should have little difficulty in building and using this antenna.

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Thank you for joining me today!

Aloha es 73 de KH6JRM--BK29jx15

Sunday, July 29, 2012

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 gauge hook up wire in a spiral along a pvc or wooden pole, the antenna would behave as a quarter-wave vertical for your chosen frequency.  As in any vertical, a good ground system would be needed.  In my case, I had a 10-foot piece of schedule 40 pvc pipe (2" diameter) under the house which could be used to wrap the wire.  For my 40-meter helix, I wound 66-feet of #22 wire along the length of the pipe and attached a 4-foot piece of an old CB antenna to the spiral to provide a bit of top-loading.  At the bottom of the pvc pipe, I attached one lead of some 450-ohm twin lead to the spiral or helix and connected the other part of the twin lead to 4, 33-foot radials.  The twin lead ran into a W9INN 4:1 balun, which was attached to approximately 25 feet of RG-6 coax (that's what I had in my storage box).  The coax was attached to the Drake MN-4 tuner, which was connected by a short piece of coax to the Swan 100-MX.

I adjusted the old Swan transceiver to 7.040 Khz, checked out the signal on the dummy load, used the Drake MN-4 to reduce the swr, and fired off a CQ.  Everything seemed to work alright, although the bandwidth was quite narrow.  From everything I've read about HF vertical helices, the impedance of the antenna is around 5 ohms, so this mismatch may preclude the use of coax for multi-band use.  The antenna works on 40, 20, 15, and 10 meters.  Performance does not match what I get from a dipole or inverted "vee".  But, with ladderline, I can get contacts on those bands, usually a s-unit below what I get on the dipole.  Your results may very, depending on the number of radials you use and the proximity to nearby objects.  As you may have guessed, this system is quite primitive and can use improvement.  The good thing about this antenna is that it's easy to build and easily hidden.  I plan to attach a better ground system when the weather improves.  I can break up the pvc support pipe into two, 5-foot sections, which fit comfortably into my van for portable use.

Now that my vacationing neighbors are scheduled to return on 31 July, it's time to take down by temporary 40-meter "long wire" (see last post).  This distant cousin of an off-center-fed dipole did fairly well under marginal propagation conditions.  I will roll up the longer 100-foot and shorter 35-foot sections and put them back in the storage chest.

I trust that your weekend was pleasant and that you had some time to work with homebrew antennas--that's half the fun of amateur radio.

Until next time,

Aloha es 73 de KH6JRM--BK29jx15

Friday, July 27, 2012

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-wave 40-meter "long wire" through the trees and tie off the end on a fence post about 100-feet from my qth.  So, using a big slingshot, some fishing line, and a 6-ounce fishing sinker, I launched this skyhook through the trees and tied off the end on the distant post.  Using the top of a spare 32-foot fiberglass pole as the first support, the antenna was run out about 100-feet throught the trees, with about 35-feet running off at a 45-degree angle as a counterpoise.  I attached about 40-feet of 450-ohm twin lead to the top of the fiberglass pole, with one wire soldered to the 100-foot of wire and the other lead soldered to the 35-foot counterpoise.  The antenna resembles a lazy inverted "L".

The twin lead goes into a 4:1 W9INN balun.  Twenty feet of RG-6 (with suitable connectors) goes to the Drake MN-4.  Three feet of RG-6 attached the tuner to the Swan 100-MX.  The antenna can be tuned from 40 to 10 meters without upsetting the old Drake or the venerable Swan.  I also have an 8-foot copper ground rod outside of the shack which is attached to two 33-foot counterpoise wires running around the property.  The antenna works fairly well, especially since the longer portion of the wire is pointed NNE--that puts most of my signal into the Pacific Northwest of the U.S. mainland.  Reports on cw run between 569 and 589 with 20 watts from the Swan 100-MX.  After Sunday, I'll have to take the antenna down.  The neighbors are due back on Monday.  In the meantime, I'm having fun.  Once Monday arrives, I'll return to the inverted "vee" and my two loop antennas.  The antenna was fairly cheap, since I used wire and connectors I already had in storage.  Besides, with all the rain our area has been receiving, I needed to take advantage of whatever sun was available.  Antenna erection day (today) was most pleasant--mostly sunny.  I probably shouldn't say much, because I see some evening showers coming towards the Hamakua coast.  Such is life.   Enjoy what you can.

Have a good, productive weekend.

Aloha es 73 de KH6JRM--BK29jx15

Wednesday, July 25, 2012

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 be the North American QSO Party (cw) on 06 August, the Worked All Europe Contest (cw) on 11 August, and the North American QSO Party (SSB) on the 18 August.  Depending on propagation, this could be fun or a real chore.  Over the past few weeks, 20 meters has been fair to poor in the central Pacific.  Of course, my timing may be wrong, too.  I've had to take care of a few teaching matters during the day, so I may have missed some good openings.

As for new antennas, I'm in the process of redoing my indoor 40 to 10 meter antenna.  I'll remove the random wire and counterpoise I installed as an experiment.  The counterpoise was becoming a safety hazard, since it snaked around the floorboards and under the rugs of my qth.  Most likely, I'll restring a 70-foot loop on the ceilings and feed it with a balun and the Drake MN-4 tuner.  That system worked well a few months ago.  As before, I will run mostly cw and SSB at 10 watts or less to reduce rfi and rf exposure. 

Have a good day and get on the air.

Aloha es 73 de KH6JRM--BK29jx15

Monday, July 23, 2012

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 decent antennas at his qth.  He designed and built computers, was knowledgeable in coding, and recently had three books published on Amazon.com.  He pursued the mystery-crime genre after he closed his CPA practice and had plans to go on a major book tour within the continental United States.

I knew both of these gentlemen and considered them close friends.  They will be missed.

Now, on to antennas.  While I was reading about stealth antennas, I came across an article written by Robert Houf, K7ZB, entitled "A 40 meter stealth vertical."  The article, originally published in antennex in 2001, was republished by Simone, IW5EDI in dx.com.  Basically, the antenna was fashioned out of collapseable aluminum tubing about 35-feet long.  The vertical was attached to the patio (or lanai if you're from Hawaii) with a homebrew swivel mount.  He fed the 35-foot tube with RG-8 and had two counterpoise wires leading away from the antenna at an angle of about 145 degrees.  The illustrations in the reprinted article are quite good and give you a thorough description of his building process.  At night, Robert would lower the antenna and lie it flat against the floor of the patio.  His bill of materials should be available at most hardware stores.  The antenna apparently does an excellent job and creates a very small footprint on his property. 

My former vertical antenna was patterned after Robert's, using a 33-foot fiberglass mast to support the wire antenna and one counterpoise running from the base of the antenna.  This antenna worked very well, considering the scarcity of space in my back yard.  And, just like Robert's antenna, my homebrew vertical could be nested to the ground by a homebrew swivel.  If you would prefer a more sturdy swivel mount, consider the various swivels offered by DX Engineering.  These mounts have received good reviews.

Until next time,
Aloha es 73 de KH6JRM--Bk29jx15

Sunday, July 22, 2012

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 wooden panels beneath the roof for an antenna support?  The roof was 10-feet above ground level--not ideal, but it could work.  I measured and cut a loop of 66-feet for the antenna, using AWG #22 gauge hookup wire I found in my junk box.  At 66-feet, the loop would be about 3-feet short according to formulas found in several antenna books.  However, my Drake MN-4 would be up to the task if I used 450-ohm ladder line and a 4:1 balun. 

After I tacked the loop onto the roof boards of the garage, I ran 20-feet of ladder line to the balun and then used 10-feet of RG-6 coax to connect the MN-4.  Three feet of RG-6 cable attached the system to the Swan MX-100.  I used RG-6 (with suitable connectors), because that's what I had on hand.  Wonder of wonders, the loop worked.  The swr is a little high on the lower portion of the band (antenna is a bit short), but the SSB part of the band can be managed nicely.  I expect to add 3-feet of wire to the loop so I can reach the bottom portion of the band without creating distress for the Drake MN-4.  Under the current configuration, the tuner doesn't get hot or arc-over.  Presently, I running about 20-watts output on SSB and CW.

Best of all, the loop is invisible to passers by.  I can use the loop on 20, 15, and 10 meters.  Like my other loop (the full-wave 40-meter loop under the house), the antenna is quiet and unobtrusive.  So far, I've made only local contacts in Hawaii.  Once conditions improve, I'll give the antenna a few more tests.  This is not an ideal antenna, but it works and blends it the environment.

The 40-meter inverted vee along the mountain side of the qth continues to perform well.  The antenna is presently nested to the ground because of a few thunderstorms last night.

Until next time,

Aloha es 73 de KH6JRM--BK29jx15

Thursday, July 19, 2012

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 antenna."  At the time of the article (06 January 2010), Flemming was a PhD candidate at the University of California, Santa Cruz and had apparently devised an antenna that gave him many contacts over the years from his small apartment.

Basically, Flemming ran 50-feet of Radio Shack wire around the ceilings of his apartment and fed the antenna into a RBA 1:1 balun attached to a LDG Z-100 automatic tuner.  He didn't say if a counterpoise was used.  Without a counterpoise, that antenna would "bite" a bit when you used a microphone.  Anyway, assuming he had a decent ground and a working counterpoise, the arrangement proved to be quiet effective in pulling in contacts. 

Here is his list of materials:

50 feet of wire, pushpins to hold up the wire along the ceiling, automatic antenna tuner (LDG Z-100 or equivalent), RBA 1:1 balun, short pieces of RG-8 or RG-58 to connect the transceiver to the antenna and tuner, and a low pass filter to reduce TVI.

Flemming advises those who wish to duplicate his success to run low power (below 100 watts), use digital modes (including cw), and reduce RF exposure and electronic interferrance (TVI) with low pass filters.

As an experiment, I made a similar antenna using 50-feet of wire with one end of some RG-6 coax connected to the wire and the other end of the coax connected to a counterpoise of 50-feet, which snaked along the floor panels and rugs in the qth.  I had an old 1:1 balun in the junk box which I interspaced between the coax and the Drake MN-4 tuner.  I had no RF feedback or "bite" when I used the microphone.  I also had my station ground connected to an 8-foot ground rod outside of the bedroom window.  The indoor antenna worked pretty well, as I received 569 to 579 reports on bands between 40 and 15 meters.  My trusty Yaesu FT-7 with its 10 watt output provide the RF source. 

Perhaps you can use Flemming's original idea for your apartment.  The antenna works given its limitations.  The important thing is getting on the air safely.

Until next time,

Aloha es 73 de KH6JRM--BK29jx15

Wednesday, July 18, 2012

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 AWG 22 gauge wire from a stock of wire in the garage to form a loop.  I made the loop slightly larger than the normal 66-feet for a full-wave 20-meter antenna.  I attached the wire to the apex of a 32-foot fiberglass mast and spread out the loop to form a fairly uniform delta shape measuring 23-feet on a side.  I fed the loop at a lower corner and ran the coax into the Drake MN-4 tuner.  The swr was no more than 1.5 to 1, a mismatch easily handled by the tuner.  Once the antenna was attached to a HI-QUE dipole connector and weatherized with tape and several layers of old plastic shopping bags, I had a good temporary 20-meter antenna for my afternoon contacts.  I will later replace the RG-6 with 450-ohm ladder line and a 4:1 balun in order to operate between 20 and 10 meters.  So far, the improvised delta loop works well and gets me many contacts.  Since I had the materials on hand, I didn't need to buy anything for this project.

My other full-wave loop is cut for 40-meters and is attached to the underside of my house.  The house is about 5-feet off the ground on a post and pier system, so there was plenty of room to lay out the antenna.  The antenna is fed with 450-ohm ladder line and can be used from 40 through 10 meters.  As mentioned in another post, this is my NVIS (near vertical incident skywave) antenna and is used primarily for local nets.  The loop also serves as an antenna for my Hallicrafters SX-62-A general coverage receiver.

There are several sources available that can help you design effective antennas for restricted spaces.  Among them is a site started by Rod Dinkins (AC6V), now a silent key.  You can find many antenna ideas by visiting ac6v.com/antprojects.htm.

Good luck in your antenna design efforts.

Aloha es 73 de KH6JRM--BK29jx15

Tuesday, July 17, 2012

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 history, created by Cliff Chang, PhD, AC6C.

I always like this historical column because it takes me back to the summer of 1977, when I first passed my Novice License test and started my official days as an amateur radio operator.  One of the engineers at the commercial radio station I called my second home came in after my air shift and administered the exam.  After two weeks of anxious waiting, my first ever amateur radio license arrived via mail from the FCC.  Armed with an old Heathkit HW-101, a J-38 key, and a simple 40-meter dipole between two Norfolk pine trees, I was on my way.

Everytime I read the "Novice History" column in the QCWA Journal I return to those days when I thought I knew everything about radio.  The passage of time has taught me that the license was only an introduction to a life time of learning--a process that has never stopped.  In those passing years, I've seen tubes transform into solid state devices and rigs transform from heavy "boat anchors" into highly portable units that can fit in your hand.  About the only thing that hasn't changed so much is the design, building, and erecting of antennas--a skill that many amateurs still practice.  Despite the availability of excellent commercial antennas, many amateurs, including yours truly, prefer to "roll our own."  This perhaps is the lingering legacy of our early days as new operators when there wasn't much money to spend on rigs or antennas.

As I look out the bedroom window facing Mauna Kea and the upland forest, I see a descendant of my original novice dipole stretched between two trees.  This 40-meter skyhook has also been converted into an inverted vee on numerous occasions.  And like my first dipole erected 35 years ago, it does a decent job on the lower 25 kHz of 40-meters.  So, in a sense, part of my novice history continues in the antennas I build and in the old rigs I repair because I'm too cheap to buy the more expensive equipment in the marketplace.  My old Swan 100 MX and an even older Kenwood TS-520 are the mainstays of my station.  An old Yaesu FT-7 goes into the van as part of my "go" kit.  I suppose I'm locked into my past, since I prefer doing my own repairs and modifying my equipment to suit my own needs.  I have nothing against the modern digital transceivers--the newer Icoms, Yaesus, Kenwoods, Elecrafts, and even Ten-Tecs are super rigs.  I just prefer the older stuff.  There is hope, though.  I'm saving up for an Elecraft K3.  At that time, I'll join the 21st century.

Once the rain stops, I'll connect the old Swan to the antenna and pound out some cw until it's time for bed.  It's been a good day to think about my radio past and to plan for my radio future.

Have an excellent day!

Aloha es 73 de KH6JRM--KK29jx15

Monday, July 16, 2012

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), there was plenty of time to set up the race track computers and hook up the track public announce system.  The auto club also has a part 15 AM station at 1620 kHz to provide continuous coverage in the pit area and the visitor viewing stands.  Under ideal conditions, the little 100 mw station can reach a mile or so before disappearing into the noise.  The track is located about 4 miles east of Hilo in the Panaewa Rain Forest and far away from the interference of power lines and industrial equipment.  So, the area is quiet before race time--ideal conditions for a small qrp operation from my van or the tower itself.

I attached the B & W apartment antenna (MFJ has a model 1622 antenna similar to this) to the tower roof and strung out 4, 33-foot radials.  Once the ladder line was attached to a 4:1 balun and the Drake MN-4 antenna tuner, I was in business.  The venerable Yaesu FT-7 performed will on 10 watts, both on cw and on SSB.  Of course, a more modern rig such as an Icom-703 or one of the Elecraft rigs would allow more flexibility, but I made do with what I had.  I had a lot of fun until I took the arrangement down at 0700 local time.  That's when the drivers and crews began to filter into the race track.  And by 0800 local time, the pit area was full of cars, motorcycles, and trucks ready for two days of pro-gas and E T Bracket Racing. 

With favorable weather, the day passed quickly as a steady stream of vehicles qualified and ran their respective races.  The tower was quite busy keeping track of racers and their times.  By the end of the day (around 1800 local time), I was ready to secure the tower and equipment until Sunday morning.  I did a bit of operating from 1900 to 2100 hours local time before the track manager and I closed the facility for the night.

A similar pattern was repeated on Sunday.  All told, I got in about 8 hours of amateur radio operations from my portable system.  Not a lot of contacts, but I did make some interesting qsos with the mainland USA and Japan.  If I do this again, I may just have to print out some special QSL cards.  This was indeed a case of mixing business with pleasure. 

You may want to try a small, mini-expedition this weekend.  Just take one of your transceivers, a portable antenna, a deep cycle marine battery, and a small antenna tuner to the beach or nearest public park.  Set up your equipment, start operating, and have some fun.  Besides, all of this is good practice for times when portable operation is needed for emergencies.

Until next time,
Aloha es 73 de KH6JRM--BK29jx15

Friday, July 13, 2012

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 are easily built, portable, and easy to maintain.  Pat notes that many amateur radio operators already have a NVIS antenna and don't know it.  All one has to do is lower a 40-meter dipole to 10 or 15 feet to get strong, no fading signals out to about 250-300 miles.  He provides the necessary graphs and test instrument readings to support his designs.  This is a good, informative read.

Next, Cecil, W5DXP, has published approximately 20 antenna ideas that could provide some excitement on your "antenna farm."  What caught my eye was what Cecil called a "no-tuner all-hf band antenna" using ladder line and a 1.1 balun.  The antenna can be either a flat-top dipole measuring 130 feet long at an elevation of 37 feet, fed by 90 to 110 feet of 450-ohm ladder line attached to a 1:1 balun.  He has a smaller design incorporating a flat-top dipole measuring 66 feet at 37 feet, fed by 60 to 90 feet of 450-ohm ladder line.  The ladder line is attached to a 1:1 balun.  Cecil provides extensive photographs, smith charts, and illustrations on how to erect this antenna. 

Finally, for your mobile operators (including me), James Bennett, KA5DVS, has reprinted his popular "Build the PAC-12 Antenna" for portable operations.  The article was published originally in issue #8 of "QRP Homebrew Magazine".  Like the other two articles, James provides an ample amount of pictures, parts lists, and construction techniques for the experimenter.  The antenna is now being marketed as a commercial product by Pacific Antenna (www.pacificantenna.com).  You can also contact the designer by visiting ka5dvs@arrl.net.

That's about all for this week.  Have a good, safe, and productive weekend.  Until next time,
Aloha es 73 de KH6JRM--BK29jx15.

Wednesday, July 11, 2012

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 waters and losing steam through sheer winds.  However, one can't be too careful, especially where tropical storms are concerned.

Local amateur radio operators, the American Red Cross, and local civil defense officials run various drills throughout the year to prepare for such eventualities.  The greatest dangers on Hawaii Island are strong, gusty winds and heavy rains which can collapse utility poles, trees, and other vegetation.  Besides the loss of power, there is the danger of closed roads due to mudslides and the loss of interisland transportation.  These problems are especially acute in rural areas such as Laupahoehoe, which has only one highway leading to the county seat at Hilo.  So, most of us living in the rural countryside prepare for the day when county, state, and federal help may be delayed.

In my own case, the xyl has stored food and water for several weeks in case we are totally cut off by natural events, including earthquakes.  All amateur radio equipment can be shifted to battery power via solar cells.  I also have backup antennas, spare rigs, coax, ladder line, and various connectors in case they are needed.

Many amateurs living on Hawaii Island also have "go" kits in their vehicles, ready for emergency service should the need arise.  My mobile go kit is simple.  There is a Yaesu FT-7, 10 watt, SSB/CW rig, a B & W apartment antenna (similar to the MFJ-1622), 50 feet of RG-6 coax, 100 feet of 450-ohm ladder line, a small MFJ antenna tuner, a deep cycle marine battery, some solar cells to charge the battery, and various connectors, tape, and a butane soldering iron.  My van also contains a 3-day supply of food, water, and medical supplies.  I make an effort to keep the gasoline tank full at all times.  If electricity is lost because of a storm, there will be no way to pump gasoline from the nearest service station.  At home, the xyl and I have a good stock of food and water, along with a two-burner propane stove.

Every so often, I take off on a mini "expedition" to test how good my emergency station works.  Most of the time, everything works as planned.  But one never knows what will happen given the nature of tropical storms.  According to the National Weather Service, the remains of these decaying storms should hit by Thursday night or Friday morning.  Hopefully, the winds and rain will pass quickly without damage.  There is one "silver lining" to the upcoming storm passage--those depending on water catchment systems should see their tanks full by the time the storms pass well south of us.

'Till next time,

Aloha es 73 de KH6JRM--BK29jx15

Monday, July 9, 2012

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 balun.  A short length of RG-6 coax with suitable connectors ran to the Drake MN-4 ATU.  A 3-foot patch cord made from RG-6 ran into the Swan 100-MX.  I tested the homebrew vertical dipole on 20, 15, and 10 meters.  The antenna caused no problems with the Drake MN-4 or the Swan-100 MX transceiver.  I also tried the vertical dipole on 40 meters just to see if it would load.  Results on 40 meters were mediocre, but I could load the antenna on this band if I had to.


The vertical dipole had several advantages, including the elimination of a radial system, which has been a problem in my small backyard.  I can also swivel the mast down to ground level quickly without tangling radial wires in the mast.  The antenna performs well, blends in with the environment, and can be safely stowed when it is not in use.


I still have the 40-meter inverted vee which performs well on 40 through 10 meters.  My backyard is getting populated by several masts and various lengths of wire.  I may have to remove some of the structures to keep the visual impact low and to keep lawn mowers out of trouble.


I'm doing as much maintenance and antenna repair as I can before school begins on 01 August.  After that date, it's back to my "regular" job as a substitute teacher.  My xyl and I get called frequently to teach, so I'm not fully retired--yet.  One must keep busy to prevent the brain from "rusting".


Have an excellent, productive day!

Aloha es 73 de KH6JRM--BK29jx15

Sunday, July 8, 2012

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 tuner.  While I was cleaning the mast and cleaning up the destruction from my little furry rodents, I noticed a 30 to 40-foot tree about 100 feet in back of the strip separating my house from the nearest neighbor.  Hmmm, I thought.  Why not string up a "long wire" from the garage roof to the tree and see what happens?  I used a similar arrangement years ago when I was a novice operator and had some good contacts.  I found several 33-foot rolls of AWG 22 gauge wire in the garage and a 40-foot length of 450-ohm ladder line from a previous experiment in the "junque" box.

I connected enough rolls of wire to make a length of 132 feet for the random wire.  I attached the wire to one lead of the ladder line, attached the other leg of the ladder line to my under-the-house 40-meter loop, and ran the assemblage to a 4:1 balun.  A short length of RG-6 coax connected the antenna to the Drake MN-4 tuner and then to the venerable Swan 100-MX.

I was able to run all bands from 80-meters through 10 meters, thanks to the ladder line and balun.  With power running between 10 and 50 watts, I was able to make plenty of daytime contacts on 20 and 15 meters by mid-afternoon.  I'll see what 80 and 40 meters does tonight.  I was able to reduce the SWR to 1.7 or better on most bands.  Nothing spectacular, of course, but contacts were made and the Drake MN-4 stayed cool.  The old Swan just chugged along without complaint. 

I will probably take the antenna down in a few days and replace it with the repaired 40 meter inverted vee.  The vee has much less visual impact than a bare wire swinging between my garage and the ohia tree.  All of this was good fun.  Besides, the project enabled me to get outside and enjoy some sun after many days of rain, gusty winds, and even thunderstorms.  Never a dull moment in the Central Pacific.

Until next time....

Aloha es 73 de KH6JRM--BK29jx15

Friday, July 6, 2012

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-meter antenna and not know it.  I found an article by Steve Hajducek, N2CKH, in the 17th Edition of ARRL's "Hints and Kinks For the Radio Amateur," p. 10-1, that may prove useful for those quick and often fleeting 6-meter contacts.  Steve found that the common 2-meter 5/8 wave base loaded antenna as well as 54-inch HF-mobile antenna masts are 1/4 wave antennas for 6-meter operation.  Steve says, "depending on the make and model of the radio, a software menu selection of antenna port or the addition of a diplexer may be all that is needed to get in on the excitement of 6-meter SSB or FM while mobile."  I've got to try Steve's idea one of these days.  I have a spare 5/8 wave 2-meter mag mount antenna that could be pressed into service.  Presently, the antenna is mounted on the metal roof of my garage and serves me quite well for repeater and simplex contacts.  The next step will be to move the old Heathkit from the storage box to the shack and see if I can find some 6-meter signals when propagation permits. 

The results of my mini expedition up an old plantation road above Laupahoehoe on 05 July were good.  Until the rains came, I managed to snag several good cw contacts with the venerable Yaesu FT-7 and the B & W apartment antenna.  The 40-meter counterpoise worked like a charm and most of my signals were 5 6 9  to 5 8 9.  Not too bad for 10 watts, a marine battery, and a compromise coil-loaded vertical.  Of course, operating from a quiet spot at the 2,000-foot level helped a lot....not to mention a clear shot to the northeast over nothing but the Pacific Ocean.  I cut the operation off after an hour or so because I heard thunder in the distance.  No sense getting fried by a stray bolt out of the blue.

I trust your 4th of July went well.

Until next time,
Aloha es 73 de KH6JRM--BK29jx15

Wednesday, July 4, 2012

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, they left some excellent roads and other infrastructure in place, giving hams and those who love the outdoors a chance to "get away from it all" without traveling miles to do so.  After charging up the road in the van, I will park at a small turnaround at the 2,000-foot elevation and set up the emergency station.  The Yaesu FT-7 will sit on a small portable table next to my Drake MN-4 ATU.  The Drake will be connected to a B & W apartment antenna (similar to the MFJ-1622).  I'll run a 33-foot counterpoise from the  operating position to a nearby tree.  Power will be supplied by a deep cycle marine battery.  I brought along a set of solar cells to keep the battery charged while I crank up the Yaesu FT-7 to a mighty 10 watts cw.  In my "go" kit I have an old J-38 key and a decades-old Yaesu hand mike.  I've used this arrangement before with good results.  A good picnic lunch and plenty of iced tea will keep the operator running for several hours.  This should be great fun in the outdoors.  If I have time, I'll erect a homebrew 2-meter beam and try to contact several repeaters on the neighbor islands.  Two meters will be served by my old, but trusty Kenwood TH-21A hand held.  I don't know how many 2-meter contacts I can make with 1 watt, but I'll try out the arrangement just for fun.

After the brief mini expedition, the xyl and I will join some neighbors in a block party.  With each home bringing something to the potluck get together, no one should go away hungry.

Enjoy the holiday and get home safely.

Aloha de KH6JRM--BK29jx15

Monday, July 2, 2012

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 higher in the 40 meter band, the third harmonic will fall outside of the band.  How do you correct this problem?

According to an article on page 9-20 of the "Hints and Kinks for the Radio Amateur, 16th edition (ARRL publication),"  the use of capacitance "hats" will lower the antenna's resonant frequency of 15 meters without seriously affecting resonance on 40 meters.  The article states, "to put this loading scheme to work, first measure, cut and adjust the 40 meter dipole to resonance at your desired frequency. Then, cut two 2-foot long pieces of stiff wire (such as #12 or #14 house wiring) and solder hte ends of each piece together in the middle to create two figure 8s.  Solder the twisted centers of your "hat" to each leg of the 40 meter antenna at a point about a third of the way out from the feed point.  Adjust the loop shapes and take measurements on 15 meters until you reach an acceptable SWR on your chosen frequency.  When you check the SWR on 40 meters, you shuld only see a minor variation."

With this in mind, I quickly assembed some extra wire, a 50-foot length of RG-6 with the proper connetors, and fed the 40 meter antenna through my trusty Drake MN-4.  Then, I made some crude loops out of #14 house wire and attached the loops as instructed.  SWR was acceptable on cw and SSB portions of both bands.  I strung this antenna as an inverted vee.  My SWR was between 1.6 to 1.8 to 1 on both 15 and 40 meters.  With proper prunning, I probably could get the SWR down a bit lower. But for now, this two-band vee works great!  You could also add a 20 meter section to the "array" with those wires running at right angles (90 degrees) to the 40 meter elements.

The antenna is cheap, easy to raise and lower, and even easier to store in the garage.  One should always have a backup antenna in case your main structure falls  victim to the weather or vandals.  This project would make an excellent antenna for shortwave listeners who prowl the 41 meter band.

Have a good day and stay safe!

Aloha es 73 de KH6JRM--BK29jx15