Return-Path: X-Spam-DCC: paranoid 1233; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE,RATWARE_GECKO_BUILD,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u5DJCDQM023967 for ; Mon, 13 Jun 2016 21:12:13 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1bCX8B-0000pB-UR for rs_out_1@blacksheep.org; Mon, 13 Jun 2016 20:02:39 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1bCX8B-0000p2-3z for rsgb_lf_group@blacksheep.org; Mon, 13 Jun 2016 20:02:39 +0100 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1bCX88-0000yD-N0 for rsgb_lf_group@blacksheep.org; Mon, 13 Jun 2016 20:02:37 +0100 Received: from dovecot03.posteo.de (dovecot03.posteo.de [172.16.0.13]) by mout01.posteo.de (Postfix) with ESMTPS id 31E9720947 for ; Mon, 13 Jun 2016 21:02:34 +0200 (CEST) Received: from mail.posteo.de (localhost [127.0.0.1]) by dovecot03.posteo.de (Postfix) with ESMTPSA id 3rT2GL0HBmz5vN4 for ; Mon, 13 Jun 2016 21:02:33 +0200 (CEST) Message-ID: <575F0349.1050708@posteo.de> Date: Mon, 13 Jun 2016 21:02:33 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <1685128417.20160531153441@chriswilson.tv> <844647135.20160607150703@chriswilson.tv> <5757E24F.1050507@posteo.de> <575AE477.3000605@posteo.de> In-Reply-To: <575AE477.3000605@posteo.de> X-Scan-Signature: 9b622d5c6a961580a0f289e85f67bcca Subject: Re: ULF: A first step on the 101 km band Content-Type: multipart/alternative; boundary="------------060100090209040502010408" X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 8257 This is a multi-part message in MIME format. --------------060100090209040502010408 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit A new step forward: Now i'm running *2 kV on 2970 Hz*. Further ERP calculations were slightly wrong. With 470 pF antenna capacity i'm getting Z = 1 kOHm -j114 kOHm, so at 2 kV the *antenna current is now 17.5 mA* and the *ERP is 39 nW*. I'm testing this voltage level now and observe the signal in 3.5 km distance. Once the 3 kV level is reached i'm planning to do a portable RX test with an E field antenna in a nice location which is 7.9 km distant. That would still be in the near field for this ultra long wavelength but i find it would be a distance that can be interpreted as respectable: 0.078 Lambda :-) The far field starts at 16 km distance... 73, Stefan Am 10.06.2016 18:01, schrieb DK7FC: > Hi all, > > I've added a small air gap to my transformer and increased the number > of turns on the transformer (which meanwhile just acts as a loading > coil). Now there are 7 layers and about 1400 turns. The new resonance > is 2.87 kHz. I put 6.8 nF (and 47kOhm in parallel) in series to the > antenna to move the resonance to 2.97 kHz. It is better to 'sit' on > top of the resonance because there is a risk of a flash over when it > starts to rain (the C of the wet antenna would be higher, so i come > closer to the resonance and so the voltage would rise). > > At 1.4 kV i'm now getting about 14 mA antenna current and 25 nW ERP! > The signal is now well visible in my 3.8 mHz window at > http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html > At 5 UTC i'm running a first EbNaut message in 10s symbols, just > local, just for the fun. > > The next step would be to wind further 1600 turns on the transformer > to reach its final voltage limit of 3 kV (rms) and 100 nW ERP. > A photo of the transformer > https://dl.dropboxusercontent.com/u/19882028/VLF/ULF%20loading%20coil%206.1H.jpg > > > 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 101 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 > --------------060100090209040502010408 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit A new step forward: Now i'm running 2 kV on 2970 Hz.

Further ERP calculations were slightly wrong. With 470 pF antenna capacity i'm getting Z = 1 kOHm -j114 kOHm, so at 2 kV the antenna current is now 17.5 mA and the ERP is 39 nW.
I'm testing this voltage level now and observe the signal in 3.5 km distance.

Once the 3 kV level is reached i'm planning to do a portable RX test with an E field antenna in a nice location which is 7.9 km distant. That would still be in the near field for this ultra long wavelength but i find it would be a distance that can be interpreted as respectable: 0.078 Lambda :-) The far field starts at 16 km distance...

73, Stefan

Am 10.06.2016 18:01, schrieb DK7FC:
Hi all,

I've added a small air gap to my transformer and increased the number of turns on the transformer (which meanwhile just acts as a loading coil). Now there are 7 layers and about 1400 turns. The new resonance is 2.87 kHz. I put 6.8 nF (and 47kOhm in parallel) in series to the antenna to move the resonance to 2.97 kHz. It is better to 'sit' on top of the resonance because there is a risk of a flash over when it starts to rain (the C of the wet antenna would be higher, so i come closer to the resonance and so the voltage would rise).

At 1.4 kV i'm now getting about 14 mA antenna current and 25 nW ERP!
The signal is now well visible in my 3.8 mHz window at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
At 5 UTC i'm running a first EbNaut message in 10s symbols, just local, just for the fun.

The next step would be to wind further 1600 turns on the transformer to reach its final voltage limit of 3 kV (rms) and 100 nW ERP.
A photo of the transformer https://dl.dropboxusercontent.com/u/19882028/VLF/ULF%20loading%20coil%206.1H.jpg

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 101 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

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