Tuesday, February 18, 2014

News From ARS W8MDE

My winter operating season got off to a rocky start.  For most of the fall of 2013 I suffered from a debilitating case of PLN or Power Line Noise. This condition has been the bane of the amateur radio operator for nearly as long as radio has been around.  Whole websites have been devoted to the problem.  Usually the cause is a worn or loose connection in the power distribution system somewhere in close proximity to a radio's antenna system.  Another cause could be a pole top transformer ready to give up the ghost.

I like to describe it this way:  Imagine that a broken insulator or jumper cable with loose hardware up on a power pole has caused a very small gap to occur in the system.  In its unending quest to keep the circuit energized the current arcs across the gap or bad connection.  The side effect of this condition is that energy that should be flowing smoothly to our homes and businesses is radiated out into space as a broadband hash loudly sizzling from the speaker of a sensitive radio receiver.

In my case the interference was a solid S9 on my signal meter.  The PLN knocked out my ability to hear anything on the HF bands except the ARRL station in Newington, CT which transmits an amplified signal with high gain antennas that point more or less towards my location.  This whole event was very disappointing because during the winter is the time I most enjoy sitting comfortably inside playing with my radio gear.

With the help of my local amateur radio club the line department was notified and after a few weeks I noticed the PLN was gone and the bands have been back to normal since the 21st of December.  Detecting problems in the power distribution grid is one of the services hams offer to their communities.  Power line noise usually goes undetected and like a leaky garden hose the end result is a wasted product not getting to its intended location.  Yes the lights still come on in the neighborhood but with local grids carrying 5000 volts or more a leak in the system if gone unnoticed ends up costing us all money.

In other ham radio news we have arrived at the high point of the 12 year solar cycle.  World wide  radio communication on the High Frequency bands is made possible by the energy flowing from our sun and the way this energy reacts with Earth's upper atmosphere.  When I first got my license in 2008 we were at the bottom of the cycle with very low sunspots or none at all.  I did make contacts none the less and had fun but it has really been exciting and interesting to witness how the increase in solar activity directly correlates to increased radio propagation here on Earth.              

Above is an electronic QSL card I received from a Russian ham named Yuri after we had a successful PSK-31 contact one evening on the 40 meter band.  I was using my 40 meter end fed wire up 40 feet. As a horizontal antenna the EFW normally works great for close in work out to a range of about 500 to 1500 miles.  Now that the ionosphere is bristling with charged ions even my lowly flat wire is transmitting a signal over 5000 miles away!


A new "old" antenna project at W8MDE

My very first amateur radio antenna I purchased from the commercial vendor Gap Antenna Products.  The attractive assembly of aluminum pictured above is called the Eagle DX.  I had the antenna mounted on a fifteen foot steel mast attached to the peak of the garage roof on the property where I lived at the time.  I used the Eagle for about a year before moving onto a different antenna so I took the antenna apart and stored it back in its original box.

The last few years I have only had a couple wire antennas up and now with the solar cycle in full swing I felt the need to get on some of the higher HF bands.  Time for the Eagle to fly once again!

The Gap antennas are unique radiators that really do work.  Technically they are multi-band vertical dipoles.  Vertical antennae have a lower radiation angle which puts signals closer to the horizon resulting in a longer "skip" distances.  A horizontal antenna shoots its signal up at steeper angles allowing it to return back to Earth much closer to it's origin.  With each successive bounce a signal loses some of its energy as it travels around the curve of the Earth.  A vertical antenna by nature of its low radiation angle makes it a good choice for "DX" or long distance communications using low power.  Less hops for a given distance means a louder signal more easily copied at the receiving end.

Dipole antennas are normally deployed in a flat or sloping position.  The Gap antenna is a dipole which means the feed point is in the middle of two antenna elements.  Unlike a traditional flat dipole the Gap is tilted up on one end.  The feed line coax does attach at the bottom end of the Eagle but a secondary piece of coax isolates the signal from the aluminum part of the antenna and deposits it at the feed point or "Gap" a thicker gray section with the yellow stripe visible in the photos.

While I was reassembling the antenna in my garage I noticed exposed wire showing at the end of one of the internal coax runs.  I made a quick call to GAP and spoke with Chris about it and he recommended simply capping off the end with a wire nut.  The original must have popped off while I was taking the antenna apart years ago.  Sure enough in my spare parts I found a wire nut that screwed down tight and even fit perfectly into the black shrink tube that was on the end of the wire. (See first assembly photo above.)  I've dealt with the guys at Gap a few times and have always had helpful and friendly service.

To operate on multiple bands the Eagle is actually a set of dipoles.  Points of resonance along the shortwave spectrum are accomplished by "tuning rods" placed around the main antenna on short PVC standoffs.

These rods work with the main body of the antenna to make up the various dipoles required for operation on the 40m, 20m, 17m, 15m, 12m and 10 meter bands.   Of course with the 40 meter end fed half wave wire already in use I wasn't concerned with the Eagle's less than stellar performance on that band.  At 21 feet tall the Eagle is just too small to be an effective radiator at 7 MHz.

At 20 meters and up on the other hand the Eagle works very well and now with the help of the sun spots and the radiation they spew forth these higher frequencies are available for long range radio fun.

My garage worked perfect for the assembly process and allowed just enough room to build the antenna.  I only had to open the back door to attach the mounting plate and short section of fiberglass mast right before taking the whole thing out to the back yard.

The following photograph shows the mounting plate attached to a short section of fiberglass mast pipe I chose because it conveniently slips into the steel pipe of my heavy duty tripod.  As a dipole the bottom end of the Eagle must be insulated from the support structure.  This is accomplished by the short PVC sections directly under the U-bolts. (In the event a metal mast pipe is used.)

Two weeks ago with the RoadQueen's assistance we erected the antenna on the tripod in the back yard.  For now the installation is temporary although we did guy the antenna using four non-conductive guy lines spaced 90 degrees apart to prevent tip over and damage in the case of high winds.

The following day we put the radiator to work making contacts from one end of the country to the other during the Straight Key Century Club's February Week End Sprint.  I made a majority of contacts during the WES on 20 meters and a couple on 10 meters.  At the same time a radio tele-type contest was going on and had the whole lower end of 40 meters booked solid with loud RTTY transmissions.  40 meters was my only band of operation before but now the Gap Eagle allows me into different areas of spectrum to meet up with other SKCC members for contacts.

Another reason I had been wanting to put up the Eagle is to take advantage of the great propagation conditions and try to put some DX stations in the log using the low power digital mode PSK.  Here is what I've got so far:

(While the first two stations are not really DX as in a foreign country I don't normally hear many western US stations with my low wire antenna so to me they are DX)

2-09-14     10.139 MHz    KA5PNX    Eagle, Nebraska         
2-10-14     28.120 MHz    N7CMJ       Kalispell, Montana    
2-11-14     14.070 MHz    ZZ80DF      Brazil                        
2-12-14     14.070 MHz    DL1FAM    Langen, Germany      
2-12-14     28.120 MHz    NP3LY        Aibonito, Puerto Rico
2-17-14     28.120 MHz    IZ0RPS       Rome, Italy
2-17-14     28.120 MHz    UR5ICG      Donetsk, Urkraine

You may notice that the first contact on my list shows the frequency at 10.139. This is the digital only 30 meter band that is one of my favorites sharing attributes of both the 40 and 20 meter bands.  The Eagle was not designed to operate on 30 meters.  Back in 2008 when I first put up the antenna I noticed while sweeping the entire short wave spectrum using an antenna analyzer coupled to the Eagle that a dip in the SWR occurred near 30 meters.  I inquired about this with Chris at Gap and he said as long I kept my transmit power at 100 watts or less I should be good to go using an antenna tuner or trans-match to even out the impedance between the antenna/feed line system and my transceiver.  Using very efficient modes like CW and digital phase shift keying the bit of loss due to the miss match is inconsequential. 

Even though I didn't "homebrew" the Eagle but put it together from a box it was still great fun to play around with aluminum out in the garage while it's too cold to do much besides ski or snowshoe outside. Making contacts with hams on the other side of the planet using the Gap Eagle is just icing on the cake.



  1. The Eagle has landed! Nice write up. A bit (a lot) over my head, but an interesting read. Very cool that you made contact at such great distance! Is 5000 miles a record for you? What is the most distant contact you've ever made?

    1. Hi Mike. I think my greatest distance 2-way comm is a station SV1BDO located in Egio, Greece. 5,213 miles. This morning I saw a station in Bangledesh which is a good bit further at 7,970 miles but he disappeared before I could try to contact him.

    2. Scratch that- Farthest distance was back in January of this year. R6AV in Russia. 5,471.9 miles.

  2. Replies
    1. I was home at lunch checking out PSK again on 10-meters and I saw the callsign ZS6AI from South Africa on my decode screen. I watched for him to reappear or call CQ but he never did. That's 8,433 miles from my location. A big part of DXing is being at the right place at the right time. -But like you say awesome indeed.

  3. Good Night esteemed colleague.
    Very good your design, beautiful photos, but excuse me if being rude, but would provide the project so I can build one for my use here in Brazil, this is not the first project that I see building also saw an extracted design ARRL HandBook 2008 in which your lordship informs that pulled such a project this vertical shortened to 40 meters.
    Since you already appreciate the attention and time spent reading this message.
    I wish lher a strong 73s extended to their families
    by PY5KYW - Marcelo