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Hello,
On Fri, 10 Dec 2010 06:15:51 -0800, Wimpie wrote: it may result in worse reception because of overloading electronic circuits in your receiver. OK for that. If your balcony has a metal fence (that may be connected to rebar also), you can use this as a ground provision for a wire antenna of about 5… 10m. I didn't test that until now. I will. Adding a 9:1 transformer (outside, directly below the antenna) will increase antenna output at the lower bands. This does not automatically mean that your S/N ratio increases also. Portable receivers may experience overload. A preselector may help. www.tetech.nl/divers/SimplePreselector2.jpg shows an (old) example. I better see what could be a home made tuner. Seems quite easy to build ![]() This one tunes from 3.3 to 26 MHz. By changing the crocodile clips, you can perform some matching to get more output from the antenna, and change the bandwidth of the preselection. The crocodile clips can be replaced by a selector. Am I OK on that? For the lower bands (AM broadcast) a loop may have advantage. Figure 2(a) in http://www.compliance-club.com/archi...ive/030718.htm shows the construction of a loop out of coaxial cable. These types of loops have built-in balanced to coaxial transition. A square or circle of about 1m (diameter) is a good start for the AM BC band. It is called a shielded loop. Am I wrong? Be careful with (expensive) loop antennas. If you can't get reception with a simple well-constructed (tuned) loop because of local interference (noise), the most expensive loop will not change that. For now, I tried a lot of different things... The best result were on loops. A big loop (1.6mx4 = 6.4 meters), one turn, with an air variable capacitor + an inside loop connected to the coaxial cable seems to give better ways to give something to eat to my receiver. Sometimes my air capacitor was not powerful enough, in the lower bands if I remember well... To improve that I will have to add a fixed capacitor (lets say 300pF) in parallel (to be bypassed) or more depending on the band I am listening to. For now I am just experimenting (with some simple wire), but I think I will build a more solid one... A big loop (1.6mx4 = 6.4 meters), one turn, with the the universal balun from Wellbrook. Don't know why, but, it gives very good results, far better than a long wire in my flat, or a short wire on my balcony... At this time it seems there is a Ham Contest in Italia... I can get them fully on 80m ![]() easier for me ![]() But the first solution seems more efficient. Need to do further investigations.... Sebastien. |
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