[Lowfer] Pixel Loop at LF ?

[Douglas D. Williams]

Having used many types of VLF-LF receive antennas over many years,
including tuned long wires, tuned loops, broadband loops, and active
whips....I prefer active whips for overall receive performance 10-500 kHz.

The caveat is that you need to deploy the active whip in a location on your
property that introduces the least VLF/LF interference. In addition, the
liberal use of common mode chokes can be of good help, in my experience.

https://dl.dropboxusercontent.com/u/33457409/LF%20common%20mode%20choke.jpg

The above photo shows six 40T1417-10H cores glued together and wrapped with
as many turns of RG-174 as I could. This goes between the DC coupler and my
active whip which is 50 ft from my house.

In addition, I use several other 40T1417-10H cores glued together and wrap
the DC supply lines, USB lines, and all other wires of my receive station.

D.



















On Tue, Dec 2, 2014 at 2:09 PM, Garry Hess <k3siw at sbcglobal.net> wrote:

> Mark,
>
> I have a Wellbrook LF 1 mtr loop (http://www.wellbrook.uk.com/
> Loop_Antennas/ALA1530LF-1) and a homebrew 1 mtr shielded loop a la VE7SL (
> http://members.shaw.ca/ve7sl/burhans.html). They perform comparably in
> terms of SNR. Jack Smith of Clifton Laboratories has made extensive S+N/N
> comparisons between the Wellbrook and Pixel loop offerings (http://www.
> cliftonlaboratories.com/Documents/Loop%20vs%20Loop%20Final-Final.pdf).
> Table 1 shows the Pixel antenna is the winner below 100 kHz and the
> Wellbrook antenna does best at MF. No comparisons are presented between
> 73.6 and 550 kHz. It seems reasonable to conclude that both antennas are
> quite comparable in performance and quality so price/availability is the
> decider. As Jay, W1VD points out LF antenna performance in practice is like
> real estate - "location, location, location". That's because the noise
> floor varies substantially with location. If you have the luxury of
> multiple sites you can benefit by trying them all to find out which is best.
>
> So far the discussion has focused on which loop is best. Unfortunately, to
> my knowledge Jack hasn't yet included a comparison to his eprobe. I made
> some limited LF comparisons between my eprobes and a 10' shielded loop and
> initially found the loop usually a bit better. However, more recently I
> find the eprobe mounted away from the house in the back yard at only 10'
> performing a bit better on most LF signals than both the 10' loop and the
> eprobe mounted atop the house at 35'. That's telling because the 10' loop
> typically has about a 10 dB SNR advantage over the 3' loop. Thus, both my
> e-probes substantially outperform my small loop antennas. Unless you need
> the nulling aspect of a loop antenna, or can build a small one with many
> more turns (like the "octalux" of W4DEX at http://www.w4dex.com/lf.htm),
> I think you'll find the eprobe hears better, at least at LF.
>
> My 2 cents worth.
>
> 73, Garry, K3SIW, EN52ta, Elgin, IL
>
>
> --
> 73, Garry, K3SIW, EN52ta, Elgin, IL
>
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