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 x0VJOYIk006427 for ; Thu, 31 Jan 2019 20:24:36 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gpHnF-0004AW-H2 for rs_out_1@blacksheep.org; Thu, 31 Jan 2019 19:14:33 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gpHnE-0004AN-RO for rsgb_lf_group@blacksheep.org; Thu, 31 Jan 2019 19:14:32 +0000 Received: from smtp3web.tin.it ([212.216.176.237]) by relay1.thorcom.net with esmtp (Exim 4.91) (envelope-from ) id 1gpHnB-0005jY-Un for rsgb_lf_group@blacksheep.org; Thu, 31 Jan 2019 19:14:31 +0000 Received: from feu14 (10.192.64.24) by smtp3web.tin.it (8.6.060.43) id 5C0CC55A00C02DF1 for rsgb_lf_group@blacksheep.org; Thu, 31 Jan 2019 20:14:27 +0100 Received: from (79.40.224.233) by webmailtin.pc.tim.it; Thu, 31 Jan 2019 20:14:27 +0100 Message-ID: <168a5557287.marcocadeddu@tin.it> Date: Thu, 31 Jan 2019 20:14:27 +0100 (CET) From: "marcocadeddu@tin.it" To: Mime-Version: 1.0 X-Originating-IP: 79.40.224.233:1768 X-Spam-Score: 1.0 (+) 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: Hi Jim, just to share my feelings / thoughs ... Since I started to play with LF I collected a number of R.I.P. caps ;-) and failure reason, on my opinion, was that the current was exceeding the capabi [...] Content analysis details: (1.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.216.176.237 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 (marcocadeddu[at]tin.it) 0.0 HTML_MESSAGE BODY: HTML included in message 1.0 FREEMAIL_REPLYTO Reply-To/From or Reply-To/body contain different freemails X-Scan-Signature: b322dc0956bb435e223041a6879534f9 Subject: R: RE: LF: TXing on indoor/outdoor loops and Silver mica caps Content-Type: multipart/alternative; boundary="----=_Part_16984_17362695.1548962067083" 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_40_50,HTML_MESSAGE 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 ------=_Part_16984_17362695.1548962067083 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi Jim, just to share my feelings / thoughs ... Since I started to play with LF I collected a number of R.I.P. caps ;-) and= failure reason, on my opinion, was that the current was exceeding the capa= bility of the cap. I was used to refer to the insulation voltage and thus seen the trepassing = of a lot of caps, the found this serie=20 http://www.cde.com/resources/catalogs/940C.pdf and never had further trespassing at least in low impedance, relative high = power: for instance for the caps insulating the dc component and carrying t= he RF power from a 500W pushpull @28Vdc. For other similar application like for instance the caps in the output LC o= f Decca style PA or Class E PA I used succesfully either the above CDE caps= or WIMA FKP1 combining series /parallel in order to have the wished capaci= tance / voltage insulation and current capability. I guess should be nice organize a day to remember all our ex-devices ;-) 73, Marco IK1HSS ----Messaggio originale---- Da: hvanesce@comcast.net Data: 31-gen-2019 18.55 A: Ogg: RE: LF: TXing on indoor/outdoor loops and Silver mica caps --> I have been using what appear to be similar polypropylene capacitors [d= ata sheet specifications (see below) including spectral loss tangent seem v= ery 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 consisten= t with the spectral loss tangent table2) No change noticed in capacitance a= fter approximately 200 of hours of transmitter operation at capacitor case = temperature of 115 F (46 C) Used 80-PHE450HD6470JR6L2 (0.47 uF) and also us= ed 0.1 uF through 1.0 uF from the same PHE450 product line; always series/p= arallel stacking capacitors of the same value to enable higher current and/= or voltage at a given capacitance. Data sheet:https://www.mouser.com/datash= eet/2/212/KEM_F3033_PHE450-1104182.pdf Reached somewhat of a practical limi= t of series/parallel stacking of these capacitors, for indoor multi-turn lo= ops 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 volt= age. I thought I had investigated (through calculations, not on the workben= ch) silver micas and found these polypropylene capacitors to be better base= d on calculations, but based on the messages between Stefan, Dimitris and M= arko 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 Dimitrio= s Polypropylene capacitors can actually self-heal to such an extent that th= ere's little left of them. The melting point of polypropylene is not very h= igh and they can end up as just a liitle blob of plastic. Don't worry thou= gh, I still use them suitably rated for the frequency in use and most of th= em are 600Vac or more. 73, Hugh, M0DSZ----- Receiving the following content= ----- From: Dimitrios Tsifakis Receiver: rsgb_lf_group Time: 2019-01-31, 0= 0:25:55Subject: 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 > ------=_Part_16984_17362695.1548962067083 Content-Type: text/html;charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Jim,
just to share my feelings / thoughs ...
Since I started to pl= ay with LF I collected a number of R.I.P. caps ;-) and failure reason, on m= y opinion, was that the current was exceeding the capability of the cap.I was used to refer to the insulation voltage and thus seen the trepassing= of a lot of caps, the found this serie

http://www.cde.com/resource= s/catalogs/940C.pdf

and never had further trespassing at least in lo= w impedance, relative high power: for instance for the caps insulating the = dc component and carrying the RF power from a 500W pushpull @28Vdc.
For = other similar application like for instance the caps in the output LC of De= cca style PA or Class E PA I used succesfully either the above CDE caps or = WIMA FKP1 combining series /parallel in order to have the wished capacitanc= e / voltage insulation and current capability.

I guess should be nic= e organize a day to remember all our ex-devices ;-)

73, Marco IK1HSS=


----Messaggio originale----
Da: hvanesce@comcast.net
Data: 31-gen-2019 18.55
A: <rsgb_lf_group@blacksheep.org>
Ogg: RE: LF: TXing on indoor/outdoor loops and Silver mica caps

 

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 an= d outdoor (35 meter x 35 meter) single-turn VLF transmitting loops for abou= t five years (when time is available) and have found the following:

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

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

 

Used 80-PHE450HD= 6470JR6L2 (0.47 uF) and also used 0.1 uF through 1.0 uF from the same PHE45= 0 product line; always series/parallel stacking capacitors of the same valu= e to enable higher current and/or voltage at a given capacitance.

 

Data sheet:

h= ttps://www.mouser.com/datasheet/2/212/KEM_F3033_PHE450-1104182.pdf=

&nb= sp;

Reach= ed somewhat of a practical limit of series/parallel stacking of these capac= itors, for indoor multi-turn loops from 1 meter diameter to ten square mete= rs, and outdoor loop 35 m x 35 m; and have hoped to find capacitors that wo= uld allow more current and voltage. I thought I had investigated (through c= alculations, not on the workbench) silver micas and found these polypropyle= ne capacitors to be better based on calculations, but based on the messages= between Stefan, Dimitris and Marko I must have missed something (perhaps t= emperature rating?); thanks for the inputs on this topic; looking forward t= o silver micas.

 

73,

 

Jim AA5BW        

&n= bsp;

Fr= om: 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
Subje= ct: Re: Re: LF: TXing WSPR/MF on an indoor loop, part 2

 

Hello Dimitrios

<= p class=3D"MsoNormal"> 

Polypropylene capacitors can actually self-h= eal to such an extent that there's little left of them. The melting point o= f 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 fre= quency in use and most of them are 600Vac or more.

 

73, Hugh, M0DSZ

----- Receiving= the following content -----

Receiver: rsgb_lf= _group

Time: 2019-01-31, 00:25:55

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

<= /div>

 

Hi Stefan,

In my experience these polypropylene capacitors when t= hey fail, they
just lose some capacitance. I think they call it 'self he= aling', maybe
they imply that when they fail there is no short circuit?<= br>
I have some really nice silver mica capacitors (ex MW broadcast stuf= f)
that would be perfect for this task...

Anyway, I am slowly gea= ring 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, singl= e 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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