[Lowfer] Can I expect to receive ....

[Douglas D. Williams]

Bill,

What you have, as far as low frequency reception goes, is a 256 foot long,
short (at our frequencies) random wire antenna.

What you need to do, like JD and others have said, is try to match that
antenna's impedance to 50 ohms at whatever frequency you are trying to
receive. This can be accomplished with an L/C "antenna tuner", or an active
device like JD has designed. In the past, I have constructed a low
frequency L/C impedance matching device for a 260' long wire antenna, based
on an R.W. Burhans article, but, though successful at impedance matching,
the antenna was (mostly) a flop at LF because of all the LF QRM present
near my QTH.

Your situation may different.

My best results at LF receiving thus far have been small active broadband
or tuned loop antennas and "active whip" broadband antennas situated in the
most QRM free spot I could logistically manage.

Andy (KU4XR), who lives only 100ish miles from me, has, however, had great
results with a long wire antenna. It's all about the local QRM and the
effort you put forth to counteract it.

Regarding software for QRSS reception, there isn't anything better than
ARGO, simple or not, IMO.

For the quickest and best results, since winter is half over, build an L/C
"antenna tuner" for your wire, download Argo, and see what you can receive.
I can try to help with a grainy photocopy of the old Burhans article.

73, Doug KB4OER











On Fri, Feb 1, 2013 at 3:54 PM, Dexter McIntyre W4DEX
<dexter.mc at gmail.com>wrote:

> I've had good success with a SDR-IQ on LF connected to unmatched wire
> antennas.  Out of curiosity I just now connected it to a 135 foot dipole
> suspended over the house.  The NDB band is very much alive but the noise
> level is very high.  I can hear 60 kHz WWVB but the signal isn't much above
> the noise.  With the SDR-IQ connected to the 40 foot near vertical wire in
> the woods some distance from the house this is what I see on VLF:
>
> https://dl.dropbox.com/u/**15095569/w4dex/sdr-iq_vlf_**01feb13.jpg<https://dl.dropbox.com/u/15095569/w4dex/sdr-iq_vlf_01feb13.jpg>
>
> You can easily see the 17 dB level changes each second of WWVB on 60 kHz
>
> Part of the NDB band looks like this:
>
> https://dl.dropbox.com/u/**15095569/w4dex/sdr-iq_ndb_**01feb13.jpg<https://dl.dropbox.com/u/15095569/w4dex/sdr-iq_ndb_01feb13.jpg>
>
> Dex
>
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