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It’s always nice to find that other people’s findings match your own. PA0RDT is famous for his design of the mini-whip, a very small but effective long- and medium wave antenna. Roelof found that the magnetic component of a radio wave could more easily go through obstacles, while the electrical component was more contained within a closed space, like a house. This means that the electrical component of noise generated by appliances in the house stays inside – mostly – while the magnetic part travels outside the walls. Thus his mini-whip design picks up the electrical component only and amplifies that. If the antenna is placed some distance from interfering obstacles it will result in a strong, but relatively noiseless signal. I build one and can say it really works.

But amplification comes at a price: IM and overload. Passive loop antennas have non of the afore mentioned problems. Since the beginning of my radio days I have always had a one metre square loop antenna for MW and LW and deep in my heart I longed for one. So I build one again, but this time bigger: 180 cm square with the corners clipped. Tuning is done remote with a BB112 varicap. The circuit was once published by the Benelux DX Club and I’ve had it for over 25 years, but never build it to this day.

Because of bad weather I could only put it up last weekend and boy, what was I disappointed. It seems it picks up all the television noise from the whole neighbourhood, with added noise from within my own house. The mini-whip is clearly better than the loop, so PA0RDT is right. But using another laptop power brick helped a bit and after firing up Argo it seemed that despite the noise the loop was still proving itself useful.

The loop tunes from 136 kHz to just above 400 kHz, which covers most of the NDB frequencies. Even though long wave beacons are on the decline there are still a lot of them. I heard some 30 new ones over the weekend, both in the daytime and at night. Argo is a great tool, sometimes beating my ears in picking up signals. Here some screen shots.

Locator “O” on 201 kHz and PQ on 202 kHz, both unidentified.

An odd one heard on 220 kHz: BRBA5. Notice that the dash in the letter “R” is longer than the other dashes. Ears won’t notice this, but with Argo you can see it.

Three beacons on the same frequency of 380 kHz: LM, OB and sandwiched in between YU from Hualien (Taiwan’s east coast).

NDBs are fun to DX, but my goal is to do some 2200m DX. Without any voltage applied to the varicap the loop is tuned to 136 kHz, which means I can leave it on all night and hope that I can detect some signals from Japanese hams, or maybe the Philippines. Unfortunately Chinese hams are not allowed to use 2200 meters and I don’t know of any Taiwanese hams operating this low. Help! I think I am becoming “low-nely.

Shortwave radio history – communications in and out of New Zealand in 1939. This history is rich with adventure and successes that are profound. Our modern communications all stems from this historic work…

This is a short film about the romance of the radiotelegraph service that utilized the high frequency spectrum known as “shortwave” (from 3 MHz up to 30 MHz) as well as the longwave and medium frequency spectrum (below 3 MHz).  This is a short film about communication to and from New Zealand on these shortwaves, using Morse code (eventually, using CW modulation). This film is a 1939 Government film scanned to 2K from a 16mm combined B/W reduction print.

http://g.nw7us.us/1cIn92f 

Every approximately eleven years, the Sun produces a “cycle” of sunspot activity. At the very lowest point in this cycle, there are few, if any, sunspots observed. Such a lack of sunspots can last for weeks. During the peak of the sunspot cycle, there can be a multitude of sunspots, ranging in size. This cycle is known as the sunspot cycle. It is caused, in part, by the magnetic activity within the Sun. Every eleven years, the Sun’s magnetic polarity flips–the north becomes south, the south becomes north. This is normal. Every twenty two years, then, the Sun goes through one full magnetic flip cycle. The flipping seems to coincide with the timing of solar cycle maxima. When it flips, we know about where we are in the eleven-year cycle. The magnetic polarity of the Sun appears to be in the process of reversing, over the next few months. If so, then we’ve pretty much reached the sunspot cycle maxima for Cycle 24. Observers note that this cycle is quite a bit less active than the last few eleven-year cycles.

A video that talks about this reversal is here:

The flipping of the Sun’s magnetic poles: Sunspot Cycle 24

More information on the Sun and the cycle, radio propagation, and related topics:

+ http://SunSpotWatch.com

On Twitter:

+ https://Twitter.com/hfradiospacewx
+ https://Twitter.com/NW7US

On Facebook:

+ http://NW7US.us/fbswhr

A magnificent eruption ejected a massive cloud of solar plasma out away from the Sun, into interplanetary space on September 29th (2013/09/29).  A long filament of plasma hovered above the photosphere, captured by the magnetism in the Sun’s northern hemisphere.  Then, it erupted in spectacular energy as seen by the Solar Dynamics Observatory, and by Stereo and SOHO spacecraft. This plasma eruption produced a stunningly beautiful coronal mass ejection (CME).

Coronal mass ejections are often associated with solar activity such as solar flares, but a causal relationship has not been established. A coronal mass ejection is also produced when a plasma filament (or prominence) breaks away from the magnetic clutch of the Sun, escaping the gravitational pull. While many plasma ejections originate from active regions on the Sun’s surface, such as groupings of sunspots associated with frequent flares, any plasma formation could break away. Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days or even less frequently.

When a CME passes Earth (not all CMEs are directed toward the Earth), it could cause geomagnetic disturbances, triggering aurora and causing disruption of shortwave radio communications.

Although this CME was not aimed at Earth, it passed by the Earth with a glancing blow from the plasma cloud on October 2-3 2013. This caused a geomagnetic storm (minor level), which lowered the Maximum Usable Frequency (MUF) over many ionospheric radio-wave propagation paths on shortwave radio.  This lowing of the MUF is often regarded as a
degradation of shortwave radio conditions.  Some aurora is also produced, though this event did not cause much significant aurora.

Here’s a video showing the magnificent plasma eruption and CME:

Credit: SOHO/Stereo/SDO/NASA

More info: http://SunSpotWatch.com and on Facebook at
https://www.facebook.com/spacewx.hfradio

Aurora Watch: http://Aurora.SunSpotWatch.com

This afternoon I hiked up to Knox Mountain with my wife and daughter. It’s a beautiful fall day. I worked two German stations and a station from Denmark. The trail was covered with dried leaves and as we walked along, we enjoyed the familiar crunching sound and the pungent smell of the season. We reached the pond after hiking 25 minutes or so.

I set up the KX3 under a cherry tree near the pond. I operated only on 20 meters. I tossed a line 50 feet over a branch and pulled up the 10 meter wire. First I heard Soren, OZ0JX in Denmark. What a beautiful signal. He gave me a 559 and we said goodbye.

A few minutes later I heard Rolf, DL3AO in Germany. We have worked a half dozen times before. Rolf was a 599 and he gave me a 559. He told me that he still hikes with his K2 at 80 years old! How wonderful to hear him again. As I finished the QSO Joerg DL2DSL called and we had a quick contact. He was a strong 599 and gave me a 559.

This is a wonderful time of year to hike in the hills. Today it was 21C and sunny. Very warm in the sun. It’s supposed to rain for the next few days, but I certainly plan to come back before the leaves are all gone.

I’ve been experimenting with magnetic loop antennas of various sizes and configurations for the past year or so. They are fun to build and even more fun to use.

QRP and Magnetic Loop antennas go hand in hand for many reasons. They work well, are very quick to set up, and are bidirectional! Its nice to be able to ‘aim’ an antenna at a prospective target, like say ‘Africa’!

Copper face plate with PL 259 and Gamma Match sticking out of the side

Soldering with a plumbing torch is necessary in some places, like attaching the main loop tubing to the PL 259. 

It may not look very pretty here, but believe it or not, my torch soldering skill is actually improving. The PL 259 is attached with screws and is soldered with a regular soldering iron to reduce inter component resistance. I’ve pretty much settled on the Gamma Match for a number of reasons. It’s easy to match and its easy to build. It works well too.

This T’ fitting helps to make the loop more stable, therefore easier to transport for portable ops.

What would hams do without PVC pipe?

Half inch PVC tubing bisects the mast and passes through the center of it. This three point connection stabilizes the loop and makes it much more robust. My first few magnetic loops didn’t have this feature and were a bit ‘wobbly, and bent more easily as they bounced around in the back of my truck.

This is the ‘business end’ of the Gamma Match 

Using a plumbing torch, I attached this copper strip to the Gamma match from the main loop tubing.

Here is another nifty improvement 

You can see the support PVC pipe passing through the center of the mast here, The black piece is a plastic pipe clamp. It is held in place with tie wraps. I try to keep the use of anything made of metal to a minimum in the center of the loop.  I’m not worried about radiation patterns as much as trying to keep the overall weight  of the antenna low. The smaller PVC pipe on the left is a tuning stick. It is tied to the capacitor and is very light and makes reaching way up to tune the antenna unnecessary. Keep in mind that merely approaching this antenna closely affects the SWR. Touching it certainly changes the SWR as well.

How Well Does It Work?

I got great signal reports today, and that is saying something for a high Q antenna and only 5 watts of RF

This is my favorite pavilion at Hagen’s Cove Florida.

Hagen’s Cove is about 17 miles from my home, along the shore route. Its a county park that is right on the Gulf of Mexico. This particular pavilion is only 50 feet from the water’s edge. I bring a sandwich and bottle water lunch, but it took me an hour to eat it today. I had very curious visitors asking a million questions about radio, and my set up. I also keep my QSL cards handy to pass around. Visitors really like seeing them.

Hagen’s Cove

There is a kayak and canoe launching ramp here. Air boats have their own launch site close by. And darn it, I forgot my noise canceling headphones today, again! Air boats pass by in only inches of water and just 50 feet away, so I can’t hear anything on the radio when that happens. I have this place all to myself during the week, but its busier on weekend as you can imagine with such a nice venue.

For more information about Magnetic Loop Antennas go to http://groups.yahoo.com/group/MagneticLoopAntenna/

or http://groups.yahoo.com/group/MagLoop/

Hagen’s Cove is in Taylor County Florida http://taylorflorida.com/

73 de AA1IK

Ernest Gregoire