Re: LF: Re: VLF in Spain

[Daniele Tincani <danieletincani@yahoo.com>]

Stefan,

in fact I tried to compare a small and simple-to-build active loop for VLF reception (ref. http://www.vlf.it/easyloop/_easyloop.htm) with a short E-probe based on your design and with another short active whip based on Steve McGreevy's BBB-4. Unfortunately, noise conditions at my location (in Livorno, Italy) are so bad that it was very hard to get acceptable results under 10KHz. Additionally, I didn't perform specific tests with the E-probes, like for example attaching them to a fishing rod (or other support) to put them well outside of my balcony at 5th floor, that probably would have given a substantial improvement. Anyway, I think I have some test results and screenshots stored on my hard disk and I will be pleased to share them with Jose. I will be sending a more informative message (hopefully) on the reflector when back to home this evening.

Now I have a new soundcard (the popular E-MU 0202) and a new portable PC, so there could be room for repeating my tests in autumn.

Best regards

Daniele

---

From: Stefan Schäfer <schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Wed, June 15, 2011 2:19:56 PM
Subject: Re: LF: Re: VLF in Spain

Hello José,

OK, but if you live in a city, brobably it is better to try a small E field antenna first. Daniele Tinacani has done many tests with loops and E field antennas on 9 kHz. Maybe he can give some further advice (if he reads this mail).
It would be worth to monitor a wideband screen to see which kind of noise affects the RX. Some EMC tricks may improve things easily by 20 dB, depending on the source and path of the noise. You can find these by testing, e.g. trying a battery instead of a normal power supply, trying a battery fed notebook instead of a normal PC, trying to ground (or not) the antenna either on the RX or antenna side, using an audio transformer to decouple an earth loop, rising the antenna by 2m (to reduce the gain and improve the wanted signal strength) and and and :-)
I remember these works and email exchanges by 4X1RF, TF3HZ, G3ZJO and others. All they have gained a lot after seeing and experimenting where the noise comes from. So the wideband screen is essential i mean...

73, GL,

Stefan/DK7FC

Am 14.06.2011 23:28, schrieb josé manuel:

Hello Stefan,

 

My idea is to use the PC as VLF RX under 10 kHz. I think that the level noise increased in my urban environment because I don´t copy  the Alpha´s transmissions now, however I could copy them some years ago, when I worked on 137 kHz. I´ll try to improve my provisional antenna system, perhaps with a loop I can reject some of the "made man noise" :-) I´ll tell you about the experiences.

 

73 de José, EA1PX

 

 

 

----- Original Message -----

From: Stefan Schäfer

To: rsgb_lf_group@blacksheep.org

Sent: Tuesday, June 14, 2011 12:18 PM

Subject: LF: VLF in Spain

Hello José,

OK. Do you already have a receiver for VLF? If so, which one? The PC's soundcard? Or do you just guess that you have strong QRM?
Many stations are in the city, like 4X1RF, SQ5BPF and me. Anyway there is good reception, 4X1RF even at above 2500 km! Others are in the countryside and have never really got good reception, so mostly its an EMC issue.
Thus i would suggest to built a suitable antenna and run a suitable software and monitor the total spectrum of your soundcard input which is mostly 0...24 kHz, often called "wideband". You can see these windows running on many grabbers such as
http://www.mydarc.de/df6nm/vlf/vlfgrabber.htm
http://www.ok2bvg.cz/vlfgrabber/
http://qsl.net/4x1rf/yo/vlfgrabber.htm
http://simnet.is/halldorgudmunds/TF3HZ_VLFgrabber/index.html
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html and many others.
Then, you'll get immediately an impression of the actual situation and see effects like mains hum, sferics and the Alphas system and some MSKs.
Seeing the Alphas and the sferics (i.e. the gap arround 8...11 UTC) is a first good indicator for sensitivity!

Actually all you need is a few Euros to build that RX antenna which can be a loop or a E field antenna. Mosty receptions were done with the E field antennas which have some advantages due to their low weight and volume. But loop antennas have shown very good results as well, mostly in quiet locations (like Paul Nicholson, F4DTL, M0BMU...).

73, Stefan/DK7FC



Am 14.06.2011 00:08, schrieb Jose Manuel:

Stefan,

 

I´ll try to do some experience on sub 9kHz reception; I´ll try to find a quiet location on holiday, because I live in a very noisy urban environment.

 

Regarding 137 kHz I had some 2-way QSO´s in the past with your country, with Wolf, Markus and others, but currently my LF antenna is down and I need to repair the SLM as well.

 

 

73 de José, EA1PX

 

 

 

 

----- Original Message -----

From: Stefan Schäfer

To: rsgb_lf_group@blacksheep.org

Sent: Monday, June 13, 2011 11:42 PM

Subject: Re: LF: ZEVS tonight.jpg

Josè,

You can get many informations about the Dreamers Band (<9) at G3XBMs sub 9 kHz website: https://sites.google.com/site/sub9khz/
Here you find record lists and advice for antennas. And you can get every information needed HERE! :-)

73, Stefan/DK7FC

Am 13.06.2011 23:30, schrieb Jose Manuel:

Mal and all,

 

You know that reception on 9 kHz is much more difficult than on 137 kHz.

I never tried to receive below 10 kHz, perhaps in a couple of weeks, when I´m on holiday ;-)

 

73, José, EA1PX

 

 

----- Original Message -----

From: mal hamilton

To: rsgb_lf_group@blacksheep.org

Sent: Monday, June 13, 2011 7:53 PM

Subject: Re: LF: ZEVS tonight.jpg

Jose

In the past you were able to copy me on CW no problem, with XBAND qso

de mal/g3kev

 

 

----- Original Message -----

From: josé manuel

To: rsgb_lf_group@blacksheep.org

Sent: Monday, June 13, 2011 4:14 PM

Subject: Re: LF: ZEVS tonight.jpg

Hi Stefan and all,

 

I´m in the NW of Spain, locator IN53ti, but with a very long path with you ;-)

 

73 de José, EA1PX

 

 

 

 

----- Original Message -----

From: Stefan Schäfer

To: rsgb_lf_group@blacksheep.org

Sent: Sunday, June 12, 2011 11:57 PM

Subject: Re: LF: ZEVS tonight.jpg

Eddie,

Where in France will you be? http://no.nonsense.ee/qthmap/ :-)
Will you be RX QRV on LF/VLF? If you are in the south, this would be an interesting region. Unfortunately there is nothing yet from Spain on VLF...

QRN will be high i assume so maybe it wouldn't be easy. Anyway iz would be worth a try. BTW i just checked for wind and the next weekend looks promising so far. If it will hold on, i'll try a kite VLF experiment but still much can change until then...

73, Stefan/DK7FC



Am 12.06.2011 23:27, schrieb qrss:

Hello Nicolas

Yes almost 100% transmissions at 0800 and 1700UTC.

Each data element is 4min  and there are 6 of those plus 'start' and 'space' makes 8 total, 32 minutes then the final long carrier 'stop' is 1 Hour.

Good luck with the antenna, yes urban noise is the big problem. Soon I will come to France to try some really quiet places, I look forward to that.

73 Eddie G3ZJO

On 12/06/2011 21:34, F4DTL@aol.com wrote:

Henny, Eddy beautifull captures.

 

It's every day at the same hour ? 0800 and 1700 UTC ?

How long the ZVES transmissions ?

I built an new VLF antenna and I'll start soon receptions.I would be in campaign to reduce urban noise.

 

F4DTL Nicolas JN18FP
http://lfistes.erst.azerttyu.net/