Return-Path: X-Spam-DCC: paranoid 1480; 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_10_20,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 u9CKWBSV023331 for ; Wed, 12 Oct 2016 22:32:11 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1buQ91-00071p-5d for rs_out_1@blacksheep.org; Wed, 12 Oct 2016 21:28:55 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1buQ90-00071g-LC for rsgb_lf_group@blacksheep.org; Wed, 12 Oct 2016 21:28:54 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1buQ8y-0001nP-DW for rsgb_lf_group@blacksheep.org; Wed, 12 Oct 2016 21:28:53 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id C5F6D20B55 for ; Wed, 12 Oct 2016 22:28:48 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3svQS00H3nz105y for ; Wed, 12 Oct 2016 22:28:47 +0200 (CEST) Message-ID: <57FE9CFF.7080903@posteo.de> Date: Wed, 12 Oct 2016 22:28:47 +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: <154c32c4dba-373a-24653@webprd-m58.mail.aol.com> <573CAF79.9040701@abelian.org> <573CBBF0.4030701@posteo.de> <573E5907.6020107@posteo.de> <573EA094.3040205@abelian.org> <573EF90F.1080201@posteo.de> <573FC4DA.3080107@abelian.org> <5740842D.3030000@posteo.de> <5744FA27.6010703@posteo.de> <57F56531.3060205@posteo.de> <57F78A3F.5030803@posteo.de> <57F80D22.2020800@posteo.de> <57F83029.8010104@posteo.de> In-Reply-To: <57F83029.8010104@posteo.de> X-Scan-Signature: fb42d311bf65eb51bbb8124890b4f977 Subject: Re: ULF: A new step on the large ULF coil... Content-Type: multipart/alternative; boundary="------------020302040101040600080102" 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 Content-Length: 7091 Status: O X-Status: X-Keywords: X-UID: 9055 This is a multi-part message in MIME format. --------------020302040101040600080102 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi ULF, In the past days i wound the rest of the available enameled cu wire onto the coil, now that's 4 kg of wire. This reduced the resonance frequency (when using a capacitor which has a C that is equivalent to the antennas C) again, from 3.667 kHz down to 3.537 kHz (so L must be 4.05 H). Today i took the coil on the roof and switched it in series to the 'small' coil that i use for 6.47 kHz (must be 1.2 H). I had clearly expected that this will reduce the resonance frequency to 2.97 kHz and even below. But obviously i am not a friend of calculations :-) I just thought "Oh well it's just a decrease of 567 Hz that i need. The coil that is fine for 6.47 kHz will do that easily". But then i found that the resonance frequency just dropped to 3.185 kHz. So the series L seems to be 5 H, which is still to low :-/ Now the coil is back in the office, further wire is ordered. The next experiment will be delayed by two weeks or so. More time for 6.47 kHz tests :-) A needless effort one can think but it was interesting to check the actual resonance and i enjoyed the nice wx during the afternoon. And BTW i saw that i can easily run > 200 mA on that frequency. 200 mA at 3185 Hz and 5 H means 20 kV which is an ERP increase of about 12 dB relative to my 31 km distance ULF experiment :-) The ERP at 20 kV would be 4 uW then. Soon more on that project... 73, Stefan PS: Of course i know that i can couple the two coils and will get more L then. But this would be a mechanically and electrically instable construction. Am 08.10.2016 01:30, schrieb DK7FC: > Hi ULF, > > This night i have completed the 4th stack of my large *ULF loading coil*. > An image: > *https://dl.dropboxusercontent.com/u/19882028/ULF/20161008_ULF_TX_coil.jpg* > > The exciting question was, what is the new resonance frequency > together with my antenna. In the lab i put an equivalent C in parallel > and found the resonance peak at *3.67 kHz*. So the L seems to be *3.8 > H* now. This is still not enough. The l/d of the coil dimension > becomes larger now, so i need more and more wire to reach the final > resonance frequency of 2.97 kHz at about 500 pF. > > I will do a next test on the actual resonance frequency in some days, > when the WX permits. I will also check where the resonance can be > found when switching the small coil in series that i use for 6.47 kHz > now. It could be quite close to 2.97 kHz then! So maybe this allows a > next QRO step on 2.97 kHz: 100 mA antenna current must be reached for > the planned experiment in 65 km distance. > > BTW the 4 stack coil is wound out of almost 4 kg of enameled Cu wire > with 0.4 mm diameter. The layers are isolated by Kapton tape. My > assumption is that it will hold 20 kV now. > Ah and the *DC resistance is 445 Ohm* now. When connecting 275 V AC / > 50 Hz, i can measure 269 mA. So the actual inductance is *2.93 H* > (beeing farer away from the self resonance frequency) > > I can tell you it's quite fascinating to operate down on these low > frequencies :-) To be continued... > > 73, Stefan/DK7FC --------------020302040101040600080102 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi ULF,

In the past days i wound the rest of the available enameled cu wire onto the coil, now that's 4 kg of wire. This reduced the resonance frequency (when using a capacitor which has a C that is equivalent to the antennas C) again, from 3.667 kHz down to 3.537 kHz (so L must be 4.05 H).
Today i took the coil on the roof and switched it in series to the 'small' coil that i use for 6.47 kHz (must be 1.2 H). I had clearly expected that this will reduce the resonance frequency to 2.97 kHz and even below. But obviously i am not a friend of calculations :-)
I just thought "Oh well it's just a decrease of 567 Hz that i need. The coil that is fine for 6.47 kHz will do that easily". But then i found that the resonance frequency just dropped to 3.185 kHz. So the series L seems to be 5 H, which is still to low :-/
Now the coil is back in the office, further wire is ordered. The next experiment will be delayed by two weeks or so. More time for 6.47 kHz tests :-)
A needless effort one can think but it was interesting to check the actual resonance and i enjoyed the nice wx during the afternoon.
And BTW i saw that i can easily run > 200 mA on that frequency. 200 mA at 3185 Hz and 5 H means 20 kV which is an ERP increase of  about 12 dB relative to my 31 km distance ULF experiment :-) The ERP at 20 kV would be 4 uW then.

Soon more on that project...

73, Stefan

PS: Of course i know that i can couple the two coils and will get more L then. But this would be a mechanically and electrically instable construction.


Am 08.10.2016 01:30, schrieb DK7FC:
Hi ULF,

This night i have completed the 4th stack of my large ULF loading coil.
An image: https://dl.dropboxusercontent.com/u/19882028/ULF/20161008_ULF_TX_coil.jpg

The exciting question was, what is the new resonance frequency together with my antenna. In the lab i put an equivalent C in parallel and found the resonance peak at 3.67 kHz. So the L seems to be 3.8 H now. This is still not enough. The l/d of the coil dimension becomes larger now, so i need more and more wire to reach the final resonance frequency of 2.97 kHz at about 500 pF.

I will do a next test on the actual resonance frequency in some days, when the WX permits. I will also check where the resonance can be found when switching the small coil in series that i use for 6.47 kHz now. It could be quite close to 2.97 kHz then! So maybe this allows a next QRO step on 2.97 kHz: 100 mA antenna current must be reached for the planned experiment in 65 km distance.

BTW the 4 stack coil is wound out of almost 4 kg of enameled Cu wire with 0.4 mm diameter. The layers are isolated by Kapton tape. My assumption is that it will hold 20 kV now.
Ah and the DC resistance is 445 Ohm now. When connecting 275 V AC / 50 Hz, i can measure 269 mA. So the actual inductance is 2.93 H (beeing farer away from the self resonance frequency)

I can tell you it's quite fascinating to operate down on these low frequencies :-) To be continued...

73, Stefan/DK7FC
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