Re: Summertime VLF: 8270.0025 Friday, Sunday

[Markus Vester <markusvester@aol.com>]

Thank you Stefan and Renato. The potential dot in Cumiana is only marginally above the noise, so I'd be reluctant to call it a successful detection yet. An earlier transmission on May 22 had actually produced an even less conspicuous pixel (attached).

I did send another carrier during the following night, 21 to 4 UT Sun/Mon. This one came out even better in Heidelberg (higher noise but stronger signal), but left no trace in Cumiana and Todmorden.

Thanks also to Max IK0VVE for his screenshot. Unfortunately I was not active on Monday evening, so the suspected line seems to be just a random alignment of noise pixels.

All the best,
Markus

 

-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>; Renato Romero <contact@vlf.it>
Verschickt: Mo, 4 Jul 2016 1:59 pm
Betreff: Fwd: Re: Summertime VLF: 8270.0025 Friday, Sunday

Hallo Markus,

Very nice! It's a short clear dit on that frequency but the identical time and frequency on the various grabbers makes it even more plausible that it's yours, so crongratulations! It is your first trace at IK1QFK, right?

73, Stefan

-------- Original-Nachricht --------

Betreff:	Re: Summertime VLF: 8270.0025 Friday, Sunday
Datum:	Sun, 3 Jul 2016 10:55:43 -0400
Von:	Markus Vester <markusvester@aol.com>
Antwort an:	rsgb_lf_group@blacksheep.org
An:	rsgb_lf_group@blacksheep.org

Great thanks to Max, Eddie and Gary for activating screen uploads.

The carrier was on air from 4:40 to 11:00 UT, with about 0.36 A antenna current and stable phase. It was nicely visible on Paul's "gold standard" spectrogram in Todmorden, and partly in 424 uHz in Heidelberg on Stefan's tree. The attached screenshot shows potential 47 uHz detections in Cumiana (IK1QFK, Friday, top) and Heidelberg (DK7FC tree, Friday and Sunday, bottom). Unfortunately today's transmission did not result in a clearer trace in Cumiana, so I'll have to try that again under quieter conditions.

Best 73,
Markus (DF6NM)




-----Ursprüngliche Mitteilung-----
Von: Markus Vester <markusvester@aol.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: So, 3 Jul 2016 12:00 am
Betreff: Summertime VLF: 8270.0025 Friday, Sunday

Yesterday (July 1st) I attempted to improve the cooling and to reduce the acoustical emission from my VLF loading coil. A large 12 volt fan was placed above the top of the coil, powered directly by the rectified antenna current. The high voltage and electric fields at the motor did not seem affect the electronic commutation. To reduce heat buildup inside the enclosure, the inner wall of the lower blue bucket was lined with a coil made of thin polyethylene tube, which was manually fed with cooling water by swapping the upper and lower canisters from time to time. Finally the remaining narrow slot between the two outer buckets was tightly sealed with tape, which indeed attenuated the annoying coil beep very significantly. 

Then I ran a carrier on 8270.0025 from 11 to 15:30 UT. Unfortunately at that time, the QRN was already quite strong, preventing a detection in the 424 uHz grabber windows of DK7FC and OK2BVG. But after the long transmission, a couple of promising brighter pixels did show up at the right place in the 47 uHz instances in Heidelberg and probably also in Cumiana at IK1QFK.

Today's weather was not favourable but we expect better conditions tomorrow morning. So if all goes well, I will try to repeat the carrier transmission on Sunday morning 6 to 11 UT (July 3rd, overlapping with SAQ), hopefully in lower background noise. Tomorrow's goal would be clearer detection in Cumiana, but of course I'd also very much appreciate possible detections from anyone anywhere else. I will also try to send more EbNaut later but not tomorrow.

BTW I have also reactivated my slow VLF grabber windows on the permanent "summer antenna" (a passive E-field probe in the garden), which  is permanently serving the 137 kHz and Loran-C receivers. On LF it is somewhat plagued by ADSL and powerline pickup, but the QRM situation may be different at 8.27 kHz. I actually need some amateur signals to find out how good it is ;-).

All the best,
Markus (DF6NM)  

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