[Lowfer] Analog VS SDR LF comparison

[Lee]

Thanks in advance for your hard work and investment of time and equipment into this very interesting subject/comparison.
Lee
KE6PCT


-----Original Message-----
>From: "Douglas D. Williams" <kb4oer at gmail.com>
>Sent: Oct 6, 2012 1:17 PM
>To: "Discussion of the Lowfer (US, European, &amp,
>	UK) and MedFer bands" <lowfer at mailman.qth.net>
>Subject: [Lowfer] Analog VS SDR LF comparison
>
>Well, as I mentioned to this group a few weeks ago, I planned to do a
>series of comparisons between an analog receiver and an SDR at VLF/LF
>frequencies, using the same antenna.
>
>In order to receive the same signal simultaneously on both receivers with
>the same antenna, I would need some sort of "splitter". KIWA Electronics
>manufactures two models:
>
>http://www.kiwa.com/LFCombiner
>
>Neither one completely covered the frequency range I am interested in,
>which is 5kHz to 500+kHz, so I commissioned a "special order" model, which
>I received today. BTW, I would like to take this opportunity to thank Craig
>Seigenthaler at KIWA for his help in this. In addition to the custom
>splitter/combiner, I own one of their 500kHz low pass filters, and can
>recommend their products without reservation. They are built like a Sherman
>tank.
>
>The antenna that will be used in this comparison is a custom Clifton
>Laboratories Z1501D active whip, located about 50' from my house with the
>base up 20' from ground. The "custom" part is I asked Jack at Clifton Labs
>to lower the bottom range of the active antenna from 20kHz to below 8kHz,
>which he did with flying colors (all the way to about 3kHz).
>
>The setup is as follows:
>
>Output from the Clifton Labs indoor DC coupler goes first to the KIWA
>500kHz low pass filter, then to the KIWA splitter. Output "A" goes to an
>AMRAD LF converter custom built by Todd Roberts with an OCXO for stability,
>then to an Icom R75 with the OCXO option, as well as a 500Hz and a 250Hz
>crystal filter. Output "B" goes directly into a Winradio Excalibur Pro
>G33DDC receiver.
>
>At first, I was going to run two instances of Argo on the same PC, one for
>each receiver, but I ultimately decided to connect the two receivers into
>two separate PCs.
>
>
>Got it all hooked up today, and here are my initial results, after briefly
>calibrating both receivers with WWVB.
>
>
>This is afternoon copy of beacon MP, both receivers tuned to 137.780 kHz,
>and the same version of ARGO running on each computer, with the settings as
>close as I could get them.
>
>Beacon MP is approximately 464 miles from my QTH. Nice daytime signal.
>
>First, the R75+AMRAD converter:
>
>https://dl.dropbox.com/u/33457409/R75%26Winradio%20Comparison/R75MP1.jpg
>
>Second, the Winradio G33DDC:
>
>https://dl.dropbox.com/u/33457409/R75%26Winradio%20Comparison/WINRADMP1.jpg
>
>
>In my opinion, there is essentially no difference in the two screen
>captures.
>
>I will continue to do direct comparisons throughout the listening season,
>at different frequencies (all 500 kHz or below).
>
>In a week or so, I am having the wooded portion of my land cleared out,
>which will put my receive antenna much more in the clear and away from
>trees.
>
>Once that happens, and the LF season really gets underway, I should be able
>to do some really "weak signal" comparisons in the Part 15 Lowfer band.
>
>-Doug KB4OER
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