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Calheta Loreto Madeira
Casa Velha Escola
22 DEC to 28 DEC, 2014
Though it's not exotic, Madeira always draws a big pile-up on the air.
Note: The wires of the antenna were enhanced in the picture for clarity.
The coax (not enhanced) is running about 5 ft. below the right leg of the antenna and not visible in this picture.
(See picture below.)
English translation follows the original German text.
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Eure Antenne 404-UL hat mich bei einem Urlaub nach Madeira begleitet.
Durch euren Leichtbau wurde das Urlaubsgepäck kaum belastet.
Am Urlaubsort habe ich die Antenne im Garten auf einem 12m Mast aufgebaut. Die Anpassung war wie beschrieben auf Anhieb gut.
Ich konnte einige schöne QSOs nach Nord- und Südamerika führen. Weiter ging es mit 100 Watt problemlos nach Südafrika. Ich habe auf 10,15 und 20m gearbeitet.
Enttäuschend waren die Signale aus Europa. Hier gab es jedoch nach einem Blick auf die Karte eine Erklärung. Europa wurde durch das Bergmassiv von Madeira abgeschirmt. Diese Berge stiegen in 7 km Entferung auf bis zu 1850m an.
Danke – sobald der Dauerregen in Deutschland vorbei ist werde ich die Antenne hier auch bei einigen SOTA Aktivitäten einsetzten.
Your Model 404-UL Antenna accompanied me on my vacation to Madeira.
The antenna's extreme lightweight had no negative impact on my vacation luggage allowance.
I installed the antenna at the vacation site on a 12m (40 ft.) fiberglass pole. The SWR was immediately as described in the advertising.
With 100 watts I was able to have several nice QSOs with North- and South America, as well as South Africa. I worked 10, 15, and 20m.
The signals from Europe were disapointing. A quick glance at the map explained it: Europe was shielded by a 1850m (6000 ft.) high mountain range just 7 km (4.5 mi.) away.
Thank you. As soon as the non-stop rain has ended, I will use the antenna here in Germany for several SOTA activities.
THE COMMITS BELOW ARE FROM AERIAL-51, NOT FROM DL8DBW
Here is a close-up photo of the antenna and its coax feedline:
What you see here is is a "worst case installation", predestined to incur Common Mode Current. Common Mode Current is any antenna's worst enemy, but especially critical with Off-Center-Fed dipoles or Inverted-V's.
Running the coax away from the antenna while keeping it equal distance from both sides will generally prevent Common Mode Current from flowing in the coax. Unfortunately this is often not possible, especially at a holiday locations like Thomas had at Madeira.
The consequences of Common Mode Current can be disasterous to an OCF antenna unless the utmost care is taken to deal with excessive Common Mode Current. Besides skewing the SWR curves, it can even cause the loss of coverage of one or more bands.
The purpose-built balun used in the Model 404-UL was designed to handle situations like this. It uses a dual-core Guanella balun with "matched pair" ferrite toroids, assuring excellent balance and the best possible protection from the ill effects of Common Mode Current.
In its design phase, the Model 404-UL was extensively stress-tested in configurations like this one and the measured results were factored into the design of the balun. Its impedance to Common Mode Current peaks in the frequency range that this type of antenna requires.
This and other quality features built into the Model 404-UL assures trouble-free operations, even in troubled installations.
- Rick, DJ0IP -