Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id x0VI2Pfe005985 for ; Thu, 31 Jan 2019 19:02:26 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gpGZm-000403-4M for rs_out_1@blacksheep.org; Thu, 31 Jan 2019 17:56:34 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gpGZc-0003zu-Sq for rsgb_lf_group@blacksheep.org; Thu, 31 Jan 2019 17:56:24 +0000 Received: from resqmta-ch2-01v.sys.comcast.net ([2001:558:fe21:29:69:252:207:33]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1gpGZa-0005Zx-Gg for rsgb_lf_group@blacksheep.org; Thu, 31 Jan 2019 17:56:23 +0000 Received: from resomta-ch2-09v.sys.comcast.net ([69.252.207.105]) by resqmta-ch2-01v.sys.comcast.net with ESMTP id pC8qgwA3Fvhl6pGZWgM7jk; Thu, 31 Jan 2019 17:56:18 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1548957378; bh=Q0KWRXdRlrCkuxNSJWwNAf5CvwXs8WdxtK6ZoBVUImI=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=L6GXKbKbWOcKj/VSiWGCXrC1bOIrty0d4hlbezIB2OawGmDw6ftuHMn+P850LWwhY gzCVdI0D/MM0YuFw9AZoZqrFepgNGtIn2CtQcnR+8mLJZCL2Y3qIAOHH8QjhcNj3qQ WZnBDHOqQI0kLl0QPOgGWIavjXy65ejmrBm7uw/McBsSXcw1SoCuDWYlv7vNEtsEV7 wkCg8WT8oQRkW0MKsNIDrHkF9+7KcsEyiZuUbz2EYZynKqJ2SnbUQAgV9E7E3/nq/K QcGe2yZDf07/EQUG2bhIfqssfNbPFVOL+BmxB7po5jdYXWWfarU9y9QfJ88qOTCxo4 8JlsN1M/fAwVA== Received: from Owner ([IPv6:2601:140:8500:7f9f:78f6:dd:b547:d008]) by resomta-ch2-09v.sys.comcast.net with ESMTPA id pGZTgzD989uakpGZUgJojA; Thu, 31 Jan 2019 17:56:17 +0000 X-Xfinity-VMeta: sc=0;st=legit From: To: Date: Thu, 31 Jan 2019 12:55:58 -0500 Message-ID: <010201d4b98e$3eebc380$bcc34a80$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AdS5jCjZ0nxCMI36SUyaXKFH8MLSYA== Content-Language: en-us X-Spam-Score: 0.3 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: I have been using what appear to be similar polypropylene capacitors [data sheet specifications (see below) including spectral loss tangent seem very similar] for multi-turn indoor and outdoor (35 met [...] Content analysis details: (0.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2001:558:fe21:29:69:252:207:33 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hvanesce[at]comcast.net) 0.0 HTML_MESSAGE BODY: HTML included in message 1.0 FREEMAIL_REPLY From and body contain different freemails X-Scan-Signature: 6ae4eec5875a1b41a36d2a35c03bf59e Subject: RE: LF: TXing on indoor/outdoor loops and Silver mica caps Content-Type: multipart/alternative; boundary="----=_NextPart_000_0103_01D4B964.56182C80" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_50_60,HTML_MESSAGE, NO_REAL_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 This is a multipart message in MIME format. ------=_NextPart_000_0103_01D4B964.56182C80 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I have been using what appear to be similar polypropylene capacitors [data sheet specifications (see below) including spectral loss tangent seem very similar] for multi-turn indoor and outdoor (35 meter x 35 meter) single-turn VLF transmitting loops for about five years (when time is available) and have found the following: 1) Temperature rise has been roughly consistent with the spectral loss tangent table 2) No change noticed in capacitance after approximately 200 of hours of transmitter operation at capacitor case temperature of 115 F (46 C) Used 80-PHE450HD6470JR6L2 (0.47 uF) and also used 0.1 uF through 1.0 uF from the same PHE450 product line; always series/parallel stacking capacitors of the same value to enable higher current and/or voltage at a given capacitance. Data sheet: https://www.mouser.com/datasheet/2/212/KEM_F3033_PHE450-1104182.pdf Reached somewhat of a practical limit of series/parallel stacking of these capacitors, for indoor multi-turn loops from 1 meter diameter to ten square meters, and outdoor loop 35 m x 35 m; and have hoped to find capacitors that would allow more current and voltage. I thought I had investigated (through calculations, not on the workbench) silver micas and found these polypropylene capacitors to be better based on calculations, but based on the messages between Stefan, Dimitris and Marko I must have missed something (perhaps temperature rating?); thanks for the inputs on this topic; looking forward to silver micas. 73, Jim AA5BW From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of dhchurch Sent: Thursday, January 31, 2019 5:55 AM To: RSGB LF group Subject: Re: Re: LF: TXing WSPR/MF on an indoor loop, part 2 Hello Dimitrios Polypropylene capacitors can actually self-heal to such an extent that there's little left of them. The melting point of polypropylene is not very high and they can end up as just a liitle blob of plastic. Don't worry though, I still use them suitably rated for the frequency in use and most of them are 600Vac or more. 73, Hugh, M0DSZ ----- Receiving the following content ----- From: Dimitrios Tsifakis Receiver: rsgb_lf_group Time: 2019-01-31, 00:25:55 Subject: Re: LF: TXing WSPR/MF on an indoor loop, part 2 Hi Stefan, In my experience these polypropylene capacitors when they fail, they just lose some capacitance. I think they call it 'self healing', maybe they imply that when they fail there is no short circuit? I have some really nice silver mica capacitors (ex MW broadcast stuff) that would be perfect for this task... Anyway, I am slowly gearing up for some VLF action over here. The other day I did some tests at 16.72 kHz into an ugly loop (very roughly 120 metres by 3 metres, single turn) and I was able to receive my signals using an unoptimise ferrite antenna at a bit over 2 km from the TX. I don't think I am in the near field at that distance, am I? :-) 73, Dimitris VK2COW > ------=_NextPart_000_0103_01D4B964.56182C80 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

I have been using what appear to be similar polypropylene capacitors = [data sheet specifications (see below) including spectral loss tangent = seem very similar] for multi-turn indoor and outdoor (35 meter x 35 = meter) single-turn VLF transmitting loops for about five years (when = time is available) and have found the following:

1) Temperature rise has been roughly consistent with the spectral = loss tangent table

2) No change noticed in capacitance after approximately 200 of hours = of transmitter operation at capacitor case temperature of 115 F (46 = C)

 

Used 80-PHE450HD6470JR6L2 (0.47 uF) and also used 0.1 uF through 1.0 = uF from the same PHE450 product line; always series/parallel stacking = capacitors of the same value to enable higher current and/or voltage at = a given capacitance.

 

Data sheet:

https://www.mouser.com/datasheet/2/212/KEM_F3033_PHE450-1104182.pdf

 

Reached somewhat of a practical limit of series/parallel stacking of = these capacitors, for indoor multi-turn loops from 1 meter diameter to = ten square meters, and outdoor loop 35 m x 35 m; and have hoped to find = capacitors that would allow more current and voltage. I thought I had = investigated (through calculations, not on the workbench) silver micas = and found these polypropylene capacitors to be better based on = calculations, but based on the messages between Stefan, Dimitris and = Marko I must have missed something (perhaps temperature rating?); thanks = for the inputs on this topic; looking forward to silver = micas.

 

73,

 

Jim AA5BW =        

 

 

Receiver: rsgb_lf_group =

Time:<= /b> = 2019-01-31, 00:25:55

Subject: = Re: LF: TXing WSPR/MF on an indoor loop, part = 2

 

Hi = Stefan,

In my experience these polypropylene capacitors when they = fail, they
just lose some capacitance. I think they call it 'self = healing', maybe
they imply that when they fail there is no short = circuit?

I have some really nice silver mica capacitors (ex MW = broadcast stuff)
that would be perfect for this = task...

Anyway, I am slowly gearing up for some VLF action over = here. The
other day I did some tests at 16.72 kHz into an ugly loop = (very
roughly 120 metres by 3 metres, single turn) and I was able to = receive
my signals using an unoptimise ferrite antenna at a bit over = 2 km from
the TX. I don't think I am in the near field at that = distance, am I?
:-)

73, Dimitris = VK2COW

>

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