Μπαλούν για κεραίες σύρματος βραχέων

How to listen to HF with a row more or less random

Usually a 'wire antenna does not have to' end the 'impedance of 50 ohms typical of any receiver that does not provide an appropriate outlet. So you have to adapt the 'impedance with a small adapter that combines antennas 300 / 500 Ohm' s input to 50 ohms. The scheme is simple: it is a transformer winding constructed on a torus, or smaller FT50/43 FT37/43 (if you can make us feel the thread) consists of a primary and a secondary 10 turns of 60 or 65 turns, with sockets every 10 turns until the thirtieth then every five so you can work on a wide enough range of impedances instead of one.

This is the pattern:

This is the torus, which as you can see is very much like a tablet with mint.

This is the torus with the wrapped sub. Does wrapping the first, using copper wire of 0.20 mm or 0.25 by calmly took all, then when finished you can cover with the primary. The two ends that go to ground are soldered together naturally.

This is the complete transformation, seen from above, settled directly on the switch.

Here you see the same side. Note the wire soldered to the center of the BNC output on the right.

Canned looks like this:

I did some tests with a long row about 50 m but folded 4 times placed at an angle to the ground, in practice it is a standard power cord for equipment covered by 1.5 mm, which from about five feet in height comes to 16 m earth and then returns to repeat the course twice. And 'quite long, but it remains locked in a courtyard surrounded by buildings almost completely, with the consequent problems.

I got so far these results: in the high bands (10 to 20 meters) of the row with the given transformer earn between 6 and 9 dB compared to the same is not granted, the low bands (30 to 40 meters) the gain is approximately equal, while in 80 and 160 m appears to decrease slightly, but it is not easy to estimate with sufficient precision. I find a slight gain in long and medium wave.

Given the low cost and simplicity of this building I recommend it to all those who dedicate themselves to 'listen with wire antennas, soon I'm going to compare it with a variometer and tabular results.