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Date: Thu, 09 Jun 2016 22:18:10 +0200
From: DK7FC <selberdenken@posteo.de>
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References: <1685128417.20160531153441@chriswilson.tv> <CAHAQVWNRW8KmN01VfnPEFNHGSUyZgsqXqZT7d+2d=hMRm45TeA@mail.gmail.com> <844647135.20160607150703@chriswilson.tv> <5757E24F.1050507@posteo.de>
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Subject: Re: ULF: A first step on the 100 km band
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Hi Paul,

It's to early to start an ULF experiment between me and you. But some 
preparations could be helpful. How do you estimate the sensitivity of 
your RX system on 2970 Hz? Is the spectrum clean or do you suffer from 
Mains QRM? Did you already put some attention to this band?

73, Stefan

Am 08.06.2016 11:15, schrieb DK7FC:
> Hi all,
>
> I've got a first result with my ULF project: One of the ideas to 
> generate and radiate a signal on the 100 km band to use a ferrite 
> power transformer with using two E cores out of N27 material. These 
> are available at https://www.buerklin.com/de/e-kern/p/83d970
> At 2970 Hz i can apply 1 V / turn without saturating the core, maybe 
> even more. I think i can generate 3 kV (rms) with one transformer 
> without a risk of a flashover. And i can set an air gap between the 
> two E cores.
>
> For 2970 Hz i need L = 6.1 H! Now without an air gap i need about 800 
> turns (hand wound!)to resonate the antenna. So i can apply 800 V now.
> On 2970 Hz, my antenna radiation resistance is 70 uOhm. With 800V on 
> the wire it radiates 6 nW!
> The distance to my remote site is 3.5 km or 0.035 lambda.
>
> I'm TXing since last night and got a trace of up to 15 dB SNR in 424 
> uHz. Quite weak but it's a first step.
> The signal was radiated with an E field antenna and received with a H 
> field antenna, so there could be a better result in the near field.
>
> I' now planning to wind more turns on the transformer and add an air 
> gap to keep the inductance and rise the voltage limit.
>
> 73, Stefan