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Re: VLF: DK7FC close to SAQ

To: [email protected]
Subject: Re: VLF: DK7FC close to SAQ
From: g3zjo <[email protected]>
Date: Tue, 28 Nov 2017 11:21:48 +0000
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Hi Dave

Stefan's e-probe design for 8.7kHz antenna and sound card RX. The BPF in the probe has quite some cut off outside sub 9kHz but maybe that's good due to the adjacent big boys.

73 Eddie

On 28/11/2017 10:58, Dave wrote:



What antenna and RX are you using for VLF, Eddie?


73, Dave G3WCB IO80EI


From: [email protected] [mailto:[email protected]] On Behalf Of g3zjo
Sent: 28 November 2017 10:49
To: [email protected]
Subject: Re: VLF: DK7FC close to SAQ


Left it on overnight.

Would you like it on 24/7, I see diurnal variations similar to Marcus but more pronounced due to my lower signal strength.

73 Eddie


On 27/11/2017 20:30, g3zjo wrote:

Hi Stefan

I didn't quite believe what I was reading you may like to take a look at my Grabber.

73 Eddie


On 27/11/2017 09:34, DK7FC wrote:

Hello Markus,

thanks for the feedback. Wonderful, now it is 30 dB in 424 uHz. DL0AO could run a 3.8 mHz '600' RDF spectrogram and a phase and signal level plot, so we could see propagation effects much better.
You could already see QRSS-60 from me! I will try that soon.
The carrier is still on the air. It will run the whole day and night...

73, Stefan

Am 26.11.2017 15:59, schrieb Markus Vester:

Yeah it's there! More than 20 dB SNR at DL0AO:

Excellent activity!

73, Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 26. Nov 2017 0:42
Betreff: VLF: DK7FC close to SAQ


Since 23 UTC a 700 mA carrier is running on
17.4701 kHz!

It is a little surprise to the VLF community i think ;-)

Legal? Yes:,47kHz_Sonderlizenz.jpg
Actually the document has 3 pages but the other ones are no so relevant.
My ERP is limited to 5 mW. I did not request more because more isn't possible anyway with this antenna.

I wound a big single layer coil with 0.5 mm enameled wire on a PVC tube with 315 mm outher diameter.

0.7 A is just a first careful step. The coil is designed to hold 1.5 A 'key down'.

The carrier will run the whole night and even tomorrow at daytime.

Worldwide reports are welcome ;-)

It is not sub-9-kHz but still VLF, the 17 km band!! So give it chance :-)

The tree has still some solar power to stream the signal from the EW loop down to the city, so there is a feedback spectrogram at

73, Stefan

PS: I still can hear that tone of the coil. It is terrible! Be happy when you are older than me!




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