[Lowfer] Analog VS SDR LF comparison

Tue Oct 9 19:07:42 EDT 2012

10 kHz - 20 MHz

I hope Jay does not mind me linking this.

(And since he has published the schematic on his own web page, I feel safe.)

D.

On Tue, Oct 9, 2012 at 6:48 PM, K2ORS <k2ors at verizon.net> wrote:

> Doug,
>    What frequency range did you get with the custom ARR preamp?
> tnx & 73 Warren
>
> ----- Original Message -----
> From: "Douglas D. Williams" <kb4oer at gmail.com>
> To: "Discussion of the Lowfer (US, European, &amp, UK) and MedFer bands"
> <lowfer at mailman.qth.net>
> Sent: Tuesday, October 09, 2012 6:37 PM
> Subject: Re: [Lowfer] Analog VS SDR LF comparison
>
>
> > Minor update.
> >
> > The KIWA splitter, being a passive unit, introduces a 6dB attenuation to
> > both output ports. Is this a problem? Most likely not, given the band
> > noise
> > at VLF/LF, and the gain at the output of the Clifton Labs Z1501D active
> > antenna.
> >
> > Regardless of that logic, I decided to obtain and introduce into the
> > entire
> > system a 20 dB preamp, and for that purpose I chose a special order model
> > by Advanced Receiver Research (our own Jay Rusgrove):
> >
> > http://www.advancedreceiver.com/
> >
> > Since that will likely produce a signal level that will drive the
> > input Winradio SDR input into clipping, I managed to bid and win on eBay
> a
> > 50 ohm, 0-50 dB step attenuator (1 dB steps) by JFW Industries, INC.
> >
> > My plan is to place the 20 dB preamp after the 500 kHz low pass filter,
> > then to the step attenuator, then the KIWA splitter, then etc. etc.
> >
> > It will likely be a haywire mess on my workbench, with all the patch
> > cords, and I am happy with that.
> >
> > -Doug KB4OER
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > On Sat, Oct 6, 2012 at 4:17 PM, Douglas D. Williams
> > <kb4oer at gmail.com>wrote:
> >
> >> 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.
> >>
> >
> >
> >
> >>  *[SNIP]*
> >>
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> >
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