Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mi05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 197EC380000A1; Sun, 31 Mar 2013 16:08:56 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UMOAf-0000Id-LE for rs_out_1@blacksheep.org; Sun, 31 Mar 2013 20:44:05 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UMOAa-0000IU-WE for rsgb_lf_group@blacksheep.org; Sun, 31 Mar 2013 20:44:01 +0100 Received: from imr-db03.mx.aol.com ([205.188.91.97]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1UMOAX-0003vW-Nr for rsgb_lf_group@blacksheep.org; Sun, 31 Mar 2013 20:43:59 +0100 Received: from mtaout-mb05.r1000.mx.aol.com (mtaout-mb05.r1000.mx.aol.com [172.29.41.69]) by imr-db03.mx.aol.com (Outbound Mail Relay) with ESMTP id 75A9338000060 for ; Sun, 31 Mar 2013 15:43:33 -0400 (EDT) Received: from White (188-195-246-26-dynip.superkabel.de [188.195.246.26]) by mtaout-mb05.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 2FA61E000144 for ; Sun, 31 Mar 2013 15:43:30 -0400 (EDT) Message-ID: <91BEEAF5B32D48F48A14DE8FE4C0BAD5@White> From: "Markus Vester" To: References: <000501ce2d39$07bdd430$6401a8c0@JAYDELL> <0BE8C4F802314145B0A4A752B6DBDFA5@Black> <001901ce2d7c$eb8cc930$6401a8c0@JAYDELL> <6A619EDB5EC748B8B3B7AE3787290027@Black> <51EA1F6C2B9B415986546992B9D67670@GaryAsus> Date: Sun, 31 Mar 2013 21:43:25 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1364759013; bh=d6Kb45aVS/Q7a1yLgroQfmrXE7vRu2xOIvSFvrMQ4ic=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=b4H3D+c9z0xNI213jwvcp1Yzm7zj4ng5af3bI/05Q1ky3aIRct/4MCpqddC/kysry ILJb/MvBFIJYzPYpuZrvfMfT/TjVNSBEJL9n2jAYSmW/3YdqgpP1fSDTB8IXFFxk2y 7EtlhzkgLzvUyBz6BXqMsGUfTCwMmSIQb4aAu7Sk= X-AOL-SCOLL-SCORE: 1:2:402111648:93952408 X-AOL-SCOLL-URL_COUNT: 1 X-Spam-Score: -1.3 (-) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Thanks Gary for pointing this out. This is a good idea, which can help minimizing internal electrical fields and effective capacitance. Actually I have used a very similar technique, the only difference being that I didn't step back up to the next layer after every single turn, but split the coil into somewhat longer sub-segments. For the first segment, I wound 9 turns on the former as a straight solenoid, than went back and wound 8 turns on top of them, then back and 7, and finally 6 turns as the fourth layer. Then stepped down again to start the second segment, which will then be 9 + 9 + 9 + 9 turns. So the maximum voltage between adjacent turns should be no more than that induced in one segment. [...] Content analysis details: (-1.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.91.97 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 SPF_PASS SPF: sender matches SPF record -1.3 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: d485dd1e9c931d17023e696bb5c40a15 Subject: Re: LF: Coil rewind (was DF6NM DK7FC in CT) Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01CE2E58.C66FF9B0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MISSING_OUTLOOK_NAME autolearn=no version=2.63 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-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-mi05.r1000.mx.aol.com ; domain : mx.aol.com DKIM : pass x-aol-sid: 3039ac1d7b8d515897d731ee X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_000A_01CE2E58.C66FF9B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Gary for pointing this out. This is a good idea, which can help = minimizing internal electrical fields and effective capacitance. Actually I have used a very similar technique, the only difference being = that I didn't step back up to the next layer after every single turn, = but split the coil into somewhat longer sub-segments. For the first = segment, I wound 9 turns on the former as a straight solenoid, than went = back and wound 8 turns on top of them, then back and 7, and finally 6 = turns as the fourth layer. Then stepped down again to start the second = segment, which will then be 9 + 9 + 9 + 9 turns. So the maximum voltage = between adjacent turns should be no more than that induced in one = segment. 25 26 27 28 29 30 59 60 ... 67 95 ... =20 18 19 20 21 22 23 24 50 51 ... 58 86 ... 10 11 12 13 14 15 16 17 41 42 ... 49 77 ... 1 2 3 4 5 6 7 8 9 32 33 ... 40 68 ... =20 However I believe that most of my extra AC losses do not stem from a = capacitive effect but are due to inductive eddy currents. In this case = they would only depend on the total number of layers and the thickness = of the wires, and not on the voltage distribution determined by the = order of turns. Best 73, Markus (DF6NM) From: Gary - G4WGT=20 Sent: Sunday, March 31, 2013 12:12 PM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Coil rewind (was DF6NM DK7FC in CT) Hi Marcus, Why not try "pyramid" winding as I have with success in making a more = compact coil, probably reducing the issues you have now, see....... http://myweb.tiscali.co.uk/wgtaylor/LF%20&%20MF%20Experiments%2010.html and http://www.oz8nj.dk/spoler.htm 73, Gary - G4WGT. ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, March 31, 2013 1:07 AM Subject: LF: Re: Re: Re: Re: DF6NM DK7FC in CT Fortunately it was not half as bad as it looks. During the = transmission I heard the fan speed up as the current from the power = supply dropped, opened the roof window where the coil is sitting, = noticed the little flames eating the white plastic bag, and blew them = out just like a birthday candle. The fire had probably started in the = greenish foam insulation where the wire from the bottom of the outer = coil runs back up to the top of the inner coil. Afterwards the whole = coil was still intact DC-wise (4 ohms) but showed slightly lower = inductance and very high RF loss resistance (about 53 ohms), apparently = a short circuit between adjacent turns. After separating the injured = turns with my fingernails, the RF resistance went back down to the = normal 7 ohms, so I'm confident that this coil can be repaired. = http://df6nm.bplaced.net/LF/pictures/topload_doubled/burnt_litz_detail_31= .jpg But I decided that I want to build a more substantial coil using Decca = RF litzwire, the "secret weapon" which serves so well in Stefan's = beautiful large glass coil. However as this insulated litz is much = thicker than the old one (4.5 mm od instead of 1.5 mm), the only way to = get a compact 5 mH coil is winding in multiple layers. Here's my first = attempt = http://df6nm.bplaced.net/LF/pictures/topload_doubled/decca_fourlayer_coil= _29.jpg , using 180 turns in a staggered four-layer winding, about 28 cm = diameter and 19 cm long in five segments. The inductance was then = adjusted by removing 18 turns from the bottom end. DC resistance is only = 1 ohm, but at 137 kHz the loss is a disappointing 6.5 ohms, hardly = better than the thin litz wire used before! This is clearly due to = proximity effect, ie eddy currents induced within each inner filament by = the magnetic field created by the outer layers. For a given strand = diameter, there must be an optimal total thickness of the layers, and = using more copper than that reduces the Q factor again. Guess I will try = to rewind this coil on a larger former in three or two layers, which = will require a longer wire but probably reduce AC losses. Antenna pulled in to low position now, watching LF but no = transmissions from here tonight. Best 73, Markus (DF6NM) ----- Original Message -----=20 From: jrusgrove@comcast.net=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Saturday, March 30, 2013 8:29 PM Subject: LF: Re: Re: Re: DF6NM DK7FC in CT Markus Sorry to hear of the mishap ... pix of the damage are always = appreciated! Wonder if your neighbors got to see the 'show'?=20 If you haven't started a fire while transmitting LF you're not running = enough power ;~) . Jay W1VD WD2XNS WE2XGR/2 ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Saturday, March 30, 2013 10:12 AM Subject: LF: Re: Re: DF6NM DK7FC in CT Here's the result of 13 minutes at 1W ERP = http://www.df6nm.bplaced.net/LF/pictures/topload_doubled/loading_coil_fir= e_28.jpg ...more work to do :-( Best 73, Markus ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Saturday, March 30, 2013 1:56 PM Subject: LF: Re: DF6NM DK7FC in CT ... At the end of a 15 minute transmission, the temperature at the = inside of the litzwire loading coil had gone up to 80=B0C, so I seem to = be limited by current rather than voltage now.=20 ... ------=_NextPart_000_000A_01CE2E58.C66FF9B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks Gary for pointing this out. This = is a=20 good idea, which can help minimizing internal electrical = fields and=20 effective capacitance.
 
Actually I have used a very similar=20 technique, the only difference being that I didn't step back = up to the=20 next layer after every single turn, but split the coil into = somewhat longer=20 sub-segments. For the first segment, I wound 9 turns on the former = as a=20 straight solenoid, than went back and wound 8 turns on top of = them,=20 then back and 7, and finally 6 turns as the fourth layer. Then = stepped down=20 again to start the second segment, which will then = be 9 + 9=20 + 9 + 9 turns. So the maximum voltage between adjacent turns should be = no more=20 than that induced in one segment.
 
    25 26 27=20 28 29 30  59 60 ... 67  95 ...  =
   18 19 20 21=20 22 23 24  50 51 ... 58  86=20 ...
  10 11 12 13 14 15 16 = 17=20  41 42 ... 49  77 ...
 1  2  = 3  4  5  6  7  8  9 =   32 33=20 ... 40  68 ...   
 
However I believe that most of my extra AC losses do not = stem=20 from a capacitive effect but are due to inductive eddy currents. In this = case they would only depend on the total number of layers and the = thickness=20 of the wires, and not on the voltage distribution determined by the = order=20 of turns.
 
Best 73,
Markus (DF6NM)
 
 
Sent: Sunday, March 31, 2013 12:12 PM
Subject: LF: Coil rewind (was DF6NM DK7FC in = CT)

Hi Marcus,
 
Why not try "pyramid" winding as I have = with=20 success in making a more compact coil, probably reducing the issues you = have=20 now, see.......
 
http://myweb.tiscali.co.uk/wgtaylor/LF%20&%20MF%20Experim= ents%2010.html
 
and
 
http://www.oz8nj.dk/spoler.htm
 
73, Gary - G4WGT.
 
----- Original Message -----
From:=20 Markus=20 Vester
Sent: Sunday, March 31, 2013 = 1:07=20 AM
Subject: LF: Re: Re: Re: Re: = DF6NM DK7FC=20 in CT

Fortunately it was not half as bad as = it looks.=20 During the transmission I heard the fan speed up as the current from = the power=20 supply dropped, opened the roof window where the coil is sitting,=20 noticed the little flames eating the white plastic bag, and blew = them out=20 just like a birthday candle. The fire had probably = started in the=20 greenish foam insulation where the wire from the bottom of the outer = coil runs=20 back up to the top of the inner coil. Afterwards the whole coil = was still=20 intact DC-wise (4 ohms) but showed slightly lower inductance = and=20 very high RF loss resistance (about 53 ohms), apparently a short = circuit=20 between adjacent turns. After separating = the injured=20 turns with my fingernails, the RF resistance went back down to the = normal 7=20 ohms, so I'm confident that this coil can be = repaired.
http://df6nm.bplaced.net/LF/pictures/topload_doubled/burnt_= litz_detail_31.jpg
 
But I decided that I want to = build a more=20 substantial coil using Decca RF litzwire, the "secret weapon" which = serves so=20 well in Stefan's beautiful large glass coil. However as=20 this insulated litz is much thicker than the old one (4.5 mm = od=20 instead of 1.5 mm), the only way to get a compact 5 mH=20 coil is winding in multiple layers. Here's = my first attempt
http://df6nm.bplaced.net/LF/pictures/topload_doubled/dec= ca_fourlayer_coil_29.jpg ,=20 using 180 turns in a staggered = four-layer=20 winding, about 28 cm diameter and 19 cm long in five=20 segments. The inductance was then adjusted by = removing 18 turns=20 from the bottom end. DC resistance is only 1 ohm, but at 137 = kHz the=20 loss is a disappointing 6.5 ohms, hardly better than the thin = litz wire=20 used before! This is clearly due to proximity effect, ie eddy currents = induced=20 within each inner filament by the magnetic field=20 created by the outer layers. For a given strand diameter, = there must=20 be an optimal total thickness of the layers, and using more = copper=20 than that reduces the Q factor again. Guess I will try to = rewind=20 this coil on a larger former in three or two layers, which will = require a=20 longer wire but probably reduce AC losses.
 
Antenna pulled in to low position = now, watching=20 LF but no transmissions from here tonight.
 
Best 73,
Markus (DF6NM)
 
 
----- Original Message -----=20
From: jrusgrove@comcast.net
Sent: Saturday, March 30, 2013 8:29 PM
Subject: LF: Re: Re: Re: DF6NM DK7FC in CT

Markus
 
Sorry to hear of the mishap ... pix = of the damage=20 are always appreciated! Wonder if your neighbors got to see the = 'show'?=20
 
If you haven't started a = fire while=20 transmitting LF you're not running enough power ;~) .
 
Jay W1VD  WD2XNS  = WE2XGR/2
----- Original Message -----
From:=20 Markus=20 Vester
To: rsgb_lf_group@blacksheep.org= =20
Sent: Saturday, March 30, = 2013 10:12=20 AM
Subject: LF: Re: Re: DF6NM = DK7FC in=20 CT

Here's the result of 13 = minutes at 1W=20 ERP
http://www.df6nm.bplaced.net/LF/pictures/topload_double= d/loading_coil_fire_28.jpg
...more work to = do :-(
 
Best 73,
Markus
 
----- Original Message -----=20
From: = Markus=20 Vester
Sent: Saturday, March 30, 2013 1:56 PM
Subject: LF: Re: DF6NM DK7FC in CT

...
At the end of a 15 minute = transmission,=20 the temperature at the inside of the litzwire loading coil had gone = up to=20 80=B0C, so I seem to be limited by current rather than voltage now.=20
...
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