{"id":467,"date":"2016-01-29T22:03:30","date_gmt":"2016-01-29T20:03:30","guid":{"rendered":"http:\/\/ha3ln.hu\/?p=467"},"modified":"2022-06-10T21:30:45","modified_gmt":"2022-06-10T19:30:45","slug":"inv-l-for-160m80m-ready","status":"publish","type":"post","link":"https:\/\/ha3ln.hu\/?p=467","title":{"rendered":"Inv-L for 160m\/80m finished"},"content":{"rendered":"


\nAfter a pretty long “off-station” preparation the day finally has come to complete the antenna. All I needed to do is include the trap and tune for 1830KHz. Actually I tested the 80m part last year in the ARRL-CW contest with pretty good result. I managed to log 171 NA QSO in the first 6 hours without special RX antenna. This was promising and I had great hopes for the 160m version as well. The last year 80m configuration had 30 ground radials (10m long) and the performance was satisfying. I planned to double this number up to 60 to see what will be the change. Unfortunately the property is 18m wide and the supporting tower is not centered therefore I have this 10m length compromise.<\/p>\n

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Of course, as each and every real ham antenna activity is finishing in the dark and cold I lived up to this standard. Actually I was lucky because the WX was very gentle compared to what it might have been in January. I had sunshine and +8 C on the peak. This was the result when I finished the matching network:<\/p>\n

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It was great to see how the ground loss is decreasing with adding more and more radials into the system. I really like when I can see the theory comes to reality.<\/p>\n

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It’s interesting the only big drop in impedance came with the first 10 radials. After doubling the radial number couple of Ohms the decrease only, which means a portion of a dB in gain. Only for reference this is what I measured in Feb\/2015 for the stand alone 80m Inv-L:<\/p>\n

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The reason might be the soil was much more humid now than last year or maybe the trap causes the difference. But anyway, it does not matter too much now.<\/p>\n

I was very curious about the end result compared to ON4UN’s book. I was satisfied when I could conclude that the “real” version in my garden knows the physics and acts very similarly to the “official” version in the LBDX. This is what I wanted and got:<\/p>\n

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Probably my SWR curve a bit more steep but I guess this is pretty close what the system can provide in band width wise. I was able to try it out before the CQ160m contest. I logged my first JA on top band. JA7NI had real s8 signal on the Inv-L (have no RX antenna yet) and he came back to me for the second call. Amazing. My smile was pretty long on my face. Finally, I have an antenna for 160m which is “not only radiating somehow”. I heard a bunch of other JAs with great signals as well, so the job was done.<\/p>\n

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