[Lowfer] Analog VS SDR LF comparison

[Douglas D. Williams]

Got it all hooked up just now. I have an octopus of patch cables all over
my desk/workbench, but my wife doesn't care, so that's that.

The AAR Preamp definitely does the job. First thing I noticed was
daytime QRN levels on 180kHz went from not registering on the S-Meter to
S7(ish). No big effect on the R75, but, as I suspected, this drove the SDR
into "ADC Clipping". Fortunately, I purchased the handy-dandy 0-50dB step
attenuator. 10dB of attenuation later, and all is well. Will probably have
to dial it down a bit more at night.

Thanks Jay. Always nice to have some extra gain when needed, and the step
attenuator give me precise control over just how much gain.

-Doug KB4OER

On Tue, Oct 9, 2012 at 7:07 PM, Douglas D. Williams <kb4oer at gmail.com>wrote:

> 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
>>
>