Re: LF: Morning enhancements of DHO38

[Daniele Tincani <danieletincani@yahoo.com>]

Hi Bill,

 

I also have an HP Pavilion DV6 with the IDT integrated audio codec (type 92HD75B, in my case). I don't think the MIC input is mono, at least on my PC model. It is a dual-use (line/mic) input. Did you try to feed the MIC input on your PC from a stereo signal source?

Best regards

Daniele

 

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From: Bill de Carle <ve2iq@magma.ca>
To: rsgb_lf_group@blacksheep.org
Sent: Tue, July 19, 2011 3:08:09 PM
Subject: Re: LF: Morning enhancements of DHO38

We are still in the midst of a power outage here after a severe storm (100 Km/H winds) Sunday evening.  It is now 39 hours with no mains power in this area.  I have been able to do some comparisons of the Mini-Whip vs two series-connected orthogonal loops favoring Europe.  Bottom line is both antennas perform well but when looking at DHO38 there is an estimated 5 dB SNR advantage using the loops.  That's consistent with the directional gain of the loop configuration.  On both antennas I see big baseline excursions (+/- 10 dB) lasting about one second.  Can't be caused by local QRM because the mains power is off all along the road here.  It looks like static crashes.  Apparently I have some coupling capacitors in the preamps which are too large for the frequencies of interest.  There isn't any visible effect on SL's waterfall because I'm not displaying such low frequencies, but I'll be looking into it.  Maybe some voltage clipping would prevent high amplitude static impulses from having any major effect on the output lines?  Not too serious because everything still stays within the allowable range for sound card inputs and there is no clipping.  I'm using an HP netbook with integrated "IDT High Definition Audio Codec" - unfortunately there is only one audio input available on the netbook (intended for a microphone) and it's mono.  Oh well...

Bill VE2IQ

At 09:50 PM 7/16/2011, VE2IQ wrote:
> At 10:21 AM 7/16/2011, Stefan wrote (about Mini-Whip):
>> Maybe it works near the trees too. The signal level will be reduced, anyway it might be OK as long as it is well above the soundcards noise. On VLF this is easily done.
>
> I found a good spot for the Mini-Whip - just above the roof of a garage about 100 feet from the shack.  Didn't want to damage the coax jacket so instead of grounding the shield DC-wise I wrapped a bunch of turns of solid copper house wire around it (about a foot along the coax) and grounded that (directly below the mini-whip).  Apparently the capacitive coupling is sufficient but your mileage may vary.
>
> I'll let it run overnight updating the grabber.  Will replot the DHO38 SNR tomorrow.