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Date: Mon, 23 Oct 2017 10:30:38 +0200
From: DK7FC <selberdenken@posteo.de>
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References: <4273a2ab-787c-d909-e7d0-d21db21ba18c@n1bug.com> <E1e63fG-00082I-VA@post.thorcom.com> <322c619f-6543-8ad4-5b0a-9a42f098467b@n1bug.com> <E1e6Hg1-000275-Hc@post.thorcom.com> <59ECC561.9040902@posteo.de> <5b388385-8cea-31e1-db86-be153479f53c@abelian.org>
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Subject: Re: VLF: VO1NA
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Hello Paul, VLF,

Am 22.10.2017 22:20, schrieb Paul Nicholson:
> Signals from Joe and Stefan have been very useful: some
> comparison S/N dB readings on recent carrier signals:
>
> DK7FC 5170.005 Hz
> -----------------
>                           Old RX   New RX
>  2017-10-21_11:00,+3.5h    13.27    17.07
>  2017-10-22_13:00,+3.5h     6.66    15.96
>
> VO1NA 8270.0075
> ---------------
>                           Old RX   New RX
>  2017-10-21_11:00,+7h       5.98     8.82

Interesting! And very promising.
Here it is the same, my VLF loops and their preamp lack sensitivity 
below 5 kHz. It is because i choose a power saving preamp design (3 mA 
at 5 V). VLF < 5 kHz was rather a low priority when i started building 
up the stuff on the tree, which is more than a year ago now.
If you can gain 2.8 dB on 8270 Hz and even 3.8 dB or more on 5.17 kHz, 
then how will it be on 2.97 kHz?!!! If you can gain 6 dB there, we could 
repeat or great result in maybe just 2 days? Hard to imagine but we will 
see. If i can manage to reach 300 mA at 2.97 kHz, the signal will be 
another 5 dB stronger!!
What about my recent EbNaut night time transmissions? You should be able 
to decode them and get additional S/N readings for comparisons at night.


> More improvement
> at lower frequencies because the old rx is pretty bad down
> there - good enough for whistlers and things but not up to par
> for weak amateur radio signals.
What's the improvement on 970 Hz? :-)

> I suspect that the extra noise was coming from the grounding
> system, either thermal noise or some sort of electrochemical
> noise. There's a nice shiny set of 6 ground rods at the new site-
>
>  https://www.screwfix.com/p/earth-rod-3-8-4ft/28044
There have been discussions about pure copper into soil, at least for 
transmit systems. I think the performance will decrease when a first 
oxide layer will have built up. Maybe this will change the performance 
of your system after some months?
For my kite experiments is used two earth rod like these: 
https://www.amazon.de/Bettermann-Kreuzerder-Staberder-Tiefenerder-4012195373636/dp/B0014DOEI6

> I'll get whatever measurements I can over the next day or two
> then the rx and antenna is back in for yet another re-build.
OK, another carrier is on the air on 5170.005 Hz since 8 UTC, unteil 16 
UTC, when the 3rd EbNaut transmission starts...

73, Stefan