At 80 meters planned to use special antenna to receive – beverage. It's a very long wire (almost 200 meters) hanging from the low height above ground, making this dish features smerovosťou – the ability to receive signals only from a specific direction. Its profit is much smaller than conventional antennas are at a greater height. In order not to differences in signal strength of both antennas large, it is necessary to use a beverage antenna preamplifier.
One design for this antenna is realized and there are details:
The first very important thing is the transfer impedance of the antenna (cca.450 Ohm) commonly used for impedance. The transformer is wound according to the recommendations W8JI nuclei dvojotvorových Amidon. Measuring the PSF confirmed excellent conversion properties. The procedure to find fold transformer http://www.w8ji.com/k9ay_flag_pennant_ewe.htm
Preamplifier that was prebudzovaný unwanted signals outside the band, is connected to the input jet outlet 3,6 – 3,98MHz and the entire block is in the shadow box. This outlet has great features and is easy to tune it. Calculation is complicated but that culverts. You can find it at: http://www.cq.sk/modules.php?name=News&file=article&sid=135
Preamplifier itself is very simple and uses the integrated circuit MMIC. Circuit used to gain some. 8dB. More is needed, otherwise there could be overloaded by strong signals entering the receiver. Very well explained the issue to Milan OK1VWK: http://www.sweb.cz/ok1vwk/K9AY%20loop%20-%20modifikace%20OK1VWK.htm
For beverage antenna was bi-direkcionálna, t.j. does not receive from two directions, be an end loaded bezindukčným resistor. Such a resistor impedance is approximately. 450 Ohm, and because of weather effects is placed in a waterproof box.
The figures can be seen without the involvement of the input transformer 9:1 and supply voltage indication (LED + resistor:
[AD-1 to #]