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Re: LF: 8.970Khz

To: [email protected]
Subject: Re: LF: 8.970Khz
From: Stefan Schäfer <[email protected]>
Date: Sun, 01 Apr 2012 20:09:30 +0200
Cc: Uwe Jannsen <[email protected]>
In-reply-to: <[email protected]>
References: <[email protected]>
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Hi Henny, Uwe, VLF,

Yesterday i did some tests with an active E field antenna in the forest. I used my normal VLF receive antenna design. First i didn't expect much since it is said that there are little chances to receive anything with an E field antenna in the forest at VLF but i got excellent results! DHO38 easily reached 50 dN S/N. The antenna was hung up 2m above the ground to a branch of a > 20m tree. A small 12V battery was used for the supply and i took a recording of about 10 minutes. In a previous test i had QRM coming from the netbook's screen but yesterday i added a single copper earth rod, 20 cm stuck into the soil. Now the QRM was completely gone and the levels rised 1 or 2 dB.

Now i want to try if i can receive your transmission Henny and Uwe, if you have the chance to transmit tomorrow between 8 UTC until the late afternoon? The longer the better. It is exciting how clean the band looks there and i really want to have a permanent remote link to my grabber PC. These are the pre tests...

Will you be on air tomorrow? :-)

As an additional test i want to add a switch into my antenna which allows to disable the high pass RC part. I will then see the difference and who knows, maybe i can receive the ZEVS on 82 Hz. At least i want to do a recording of  > 1 hour. That is such a fascinating WX here! I love it.

Also i want to do a new VLF transmission test with the small LOPT transformer from an old TV. It became wet during the last test and then i had a flash over. Maybe it is damaged but maybe not. If not, i will transmit at 8972 Hz or so and try to decode a WOLF10 signal on VLF.

I also ordered some audio transformers in different winding ratios. A galvanic decoupling, optimal matching to the soundcard, first using a 4:1 and then a 1:10 xfmr with a local ground between the transformers may help to get a lower noise floor on my 2 orthogonal VLF loops which generate the signals for the CDF VLF grabber at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html

73, Stefan/DK7FC



Am 01.04.2012 10:34, schrieb henny van elst:
Gm LF,
the tx is on,8.970 Khz 450 mA antenna current
henny pa3cpm
73's
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