Return-Path: X-Spam-DCC: paranoid 1170; 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=-1.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE,NO_REAL_NAME 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 u18JHlvT024077 for ; Mon, 8 Feb 2016 20:17:47 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1aSrEN-0005a7-Mm for rs_out_1@blacksheep.org; Mon, 08 Feb 2016 19:12:15 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1aSrEN-0005Zy-0y for rsgb_lf_group@blacksheep.org; Mon, 08 Feb 2016 19:12:15 +0000 Received: from resqmta-po-06v.sys.comcast.net ([96.114.154.165]) by relay1.thorcom.net with esmtps (TLSv1.2:DHE-RSA-AES256-SHA:256) (Exim 4.86) (envelope-from ) id 1aSrDR-0005lF-AR for rsgb_lf_group@blacksheep.org; Mon, 08 Feb 2016 19:12:13 +0000 Received: from resomta-po-20v.sys.comcast.net ([96.114.154.244]) by resqmta-po-06v.sys.comcast.net with comcast id Fv9Q1s0065Geu2801vA0RF; Mon, 08 Feb 2016 19:10:00 +0000 Received: from Owner ([IPv6:2601:141:1:c7e9:7144:ca07:35cc:8f2a]) by resomta-po-20v.sys.comcast.net with comcast id Fv9y1s0034EC3EN01v9ySZ; Mon, 08 Feb 2016 19:09:59 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK From: To: References: <00a801d161fd$1b66ff10$5234fd30$@comcast.net> <56B7D569.1030908@virginbroadband.com.au> In-Reply-To: <56B7D569.1030908@virginbroadband.com.au> Date: Mon, 8 Feb 2016 14:09:55 -0500 Message-ID: <013701d162a4$4c6aa0b0$e53fe210$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQIoj0jDgN1mE6io0sVsk882nKYcngLCDOTxAlKEqzCeS2tV0A== Content-Language: en-us DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1454958600; bh=59lyqJMaRxE0DJcDFLhwpyMLSz7hDwHSEpFTteCQ624=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=JMzDVkB93YqgSuEr/DrEZ7hjQLmNm+fc1agk4VGzf10MqxewlfTK0iUty3eLh9clq 563NCj+fvYT6Xz+AEULdVcYYWZUrAO6IwQnWxEDzJH17YerUiKJrlfMV0Jg2mF4APc ycYI+PaQZI52LPFZCvjqRYedtfBbIpT36iTCjraYAPZqEmKrpBaio7vzu2t2rLwR2K HSmERJwVY6frWBCXB35hblfwSmQgz/titFlob+UIO4jvNJNk9rowSXhO96WQPoFMKx CyNTw6qlI+3lYwRSZ2EAP1fOp8bp3e73gGlr5s6qb+94ScYOIibn8asHx2LqxP8sR3 SdhuK1+vea0qQ== X-Scan-Signature: d2a449809c9c1ff1983612d049372878 Subject: RE: LF: RE: Vlf ot Penguins and awesomes Content-Type: multipart/alternative; boundary="----=_NextPart_000_0138_01D1627A.639709B0" 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 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 6753 This is a multipart message in MIME format. ------=_NextPart_000_0138_01D1627A.639709B0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Edgar, =20 Excellent find, thanks for posting, hope it answers Laurence=E2=80=99s = questions. =20 A comment regarding the summary (last paragraph) on .pdf page 32, = original document page 27: prototype transformer C_s can deviate = considerably from initial design value especially if a simplified model = for C_s is used in the design or design spec for the magnet wire is not = controlled for insulation type and winding/layering method. If a = transformer modeling tool is not available, the old Radiotron = Engineer=E2=80=99s Handbook has some helpful models. =20 =20 Note Paschal=E2=80=99s comment in a related context (C_a of loop) in = paragraph 1, .pdf pg 40, original document pg 35: =E2=80=9C...it is difficult to calculate the value of C_a = =E2=80=A6easier to build and measure=E2=80=9D. In the case of the matching transformer, using a transformer model that = has a reasonable approximation for C_s could save a fair amount of = test/rewind time on the way to a VLF receiver with sensitivity of = 0.5uV/m-Hz^1/2 (measured, Fig 8.5, .pdf pg 78) =20 =20 Of interest in context of C_s: Item 4, .pdf page 44, original document page 40; and last paragraph, = same page Item 2 (packing density), .pdf page 47, original document page 43 Item 4, .pdf page 47, original document page 43 Paragraph 2 (Litz wire tradeoffs), .pdf page 49, original document page = 45 Last paragraph on .pdf page 52, original document page 56 (in the = context of high-impedance preamps): =E2=80=9CC_s forms a tuned = circuit=E2=80=A6 (therefore) low-impedance amplifiers are a much better = practical solution=E2=80=9D =20 I wonder if page 38 of the original document is blank. It=E2=80=99s not = included in the .pdf document (which is why the offset between .pdf page = number and original document page number changes after original document = page 37) =20 Thanks for posting the link; hope it answers Laurence=E2=80=99s = questions; I had been looking for this article off and on since seeing a = reference to it some years ago. =20 73, =20 Jim AA5BW=20 =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of edgar Sent: Sunday, February 7, 2016 6:38 PM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: RE: Vlf ot Penguins and awesomes =20 Hi Laurence, You probably have this, but in case you do not. http://traktoria.org/files/radio/antenna/VLF/the_design_of_broad-band_vlf= _receivers_with_air-core_loop_antennas.pdf It may not answer your questions. Regards, Edgar Moonah, Tasmania. ------=_NextPart_000_0138_01D1627A.639709B0 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

Edgar,

 

Excellent find, thanks for posting, hope it answers = Laurence=E2=80=99s questions.

 

A comment regarding the summary (last paragraph) on .pdf page 32, = original document page 27: prototype transformer C_s can deviate = considerably from initial design value especially if a simplified model = for C_s is used in the design or design spec for the magnet wire is not = controlled for insulation type and winding/layering method. If a = transformer modeling tool is not available, the old Radiotron = Engineer=E2=80=99s Handbook has some helpful models. = =C2=A0

 

Note Paschal=E2=80=99s comment in a related context (C_a of loop) in = paragraph 1, =C2=A0.pdf pg 40, original document pg = 35:

=E2=80=9C...it is difficult to calculate the value of C_a=C2=A0=C2=A0 = =C2=A0=E2=80=A6easier to build and = measure=E2=80=9D.

In the case of the matching transformer, using a transformer model = that has a reasonable approximation for C_s could save a fair amount of = test/rewind time on the way to a VLF receiver with sensitivity of = 0.5uV/m-Hz^1/2 (measured, Fig 8.5, .pdf pg 78) = =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0<= /p>

 

Of interest in context of C_s:

Item 4, =C2=A0.pdf page 44, original document page 40; and last = paragraph, same page

Item 2 (packing density), =C2=A0.pdf page 47, original document page = 43

Item 4, =C2=A0.pdf page 47, original document page = 43

Paragraph 2 (Litz wire tradeoffs), .pdf page 49, original document = page 45

Last paragraph on .pdf page 52, original document page 56 (in the = context of high-impedance preamps): =C2=A0=E2=80=9CC_s forms a tuned = circuit=E2=80=A6 (therefore) low-impedance amplifiers are a much better = practical solution=E2=80=9D

 

I wonder if page 38 of the original document is blank. It=E2=80=99s = not included in the .pdf document (which is why the offset between .pdf = page number and original document page number changes after original = document page 37)

 

Thanks for posting the link; hope it answers Laurence=E2=80=99s = questions; I had been looking for this article off and on since seeing a = reference to it some years ago.

 

73,

 

Jim AA5BW

 

From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of = edgar
Sent: Sunday, February 7, 2016 6:38 PM
To: = rsgb_lf_group@blacksheep.org
Subject: Re: LF: RE: Vlf ot = Penguins and awesomes

 

Hi Laurence,

You = probably have this, but in case you do not.

http://traktoria.org/= files/radio/antenna/VLF/the_design_of_broad-band_vlf_receivers_with_air-c= ore_loop_antennas.pdf

It may not answer your = questions.

Regards, Edgar
Moonah, = Tasmania.

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