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LOG Not Performing Well

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ultravista:
I built a 60 foot LOG yesterday using a DX Engineering BFS-1 at the feed point. The wire is solid core thin telephone cross-connect wire.

The LOG is very quiet and barely picks up distant signals. Compared to my Pixel 1B mag loop, this thing is practically dead.

I have watched numerous videos and read a lot about the LOG and mine is not as effective as others. This LOG is deaf on160 and 80 meters.

Any suggestions on what to do?

ultravista:
Interesting, at night, the LOG is different. I am picking up Israel 4XZ @ 4133 Khz with the LOG and Pixel. Also found conversations @ 160 and 80 meters. Not sure why day/night makes a difference.

Ray Wraye:
 Funny you should ask  :)  I have spent the past month or so working on a LOG for my LF/HF RX. Mine ended up 300 feet long, 75' per side square.  I made my own matching transformer (?) , a simple 5:2 wound with magnet wire using a binocular core torrid as my feedlines are 75 ohm.  It is incredibly quiet, but....I need to run a lot a gain sometimes (MOST times), depending on conditions. All I have to compare it to is (was) a 120' end feed longwire with a 9:1 balun, until a recent wind took it down.

The Longwire seemed to pick up more signals, but there was a lot of noise as well. The LOG signal levels are much lower, but I can really crank the gain with the low background noise.  As with most antennas I ever bought, built and/or used...Conditions are everything. During the day on MW and HF it is pretty good, but after sunset it reallys seems to come alive. LF is all but dead during the day, but at night it's a totally different story.

My radios are a SDR and a Kenwood R1000, so nothing incredible there, but I do use a homemade pre-selector and preamp and it seems to help, again...depending on conditions

Ray Ray

~SIGINT~:
The use of small AWG telephone wire may not be the best choice in antenna wire. This wire has a typical DC resistance of approx 98 Ohms per km and a characteristic impedance of 100 Ohms from 1 to 20 MHz.

Attenuation is in the range of:
2.6 dB/100m at 1 MHz;
5.6 dB/100m at 4 MHz;
8.5 dB/100m at 8 MHz;
9.8 dB/100m at 10 MHz; and
13.1 dB/100m at 16 MHz.

Unfortunately, the result being that the signals captured by the antenna are substantially attenuated by the length of telephone wire even before they have the opportunity to hit the receiver input.

ultravista:

--- Quote from: Ray Wraye on September 08, 2021, 0220 UTC ---Ray Ray

--- End quote ---

Nice to meet another Ray on the board.

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