Return-Path: Received: from mtain-dd01.r1000.mx.aol.com (mtain-dd01.r1000.mx.aol.com [172.29.64.141]) by air-da09.mail.aol.com (v129.4) with ESMTP id MAILINDA094-86934d0a87883b3; Thu, 16 Dec 2010 16:41:29 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dd01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6BE3F380000D9; Thu, 16 Dec 2010 16:41:27 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PTLZ4-0001fj-EF for rs_out_1@blacksheep.org; Thu, 16 Dec 2010 21:40:42 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PTLZ3-0001fZ-Rm for rsgb_lf_group@blacksheep.org; Thu, 16 Dec 2010 21:40:41 +0000 Received: from nm13.bullet.mail.sp2.yahoo.com ([98.139.91.83]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1PTLZ1-0008Ls-D2 for rsgb_lf_group@blacksheep.org; Thu, 16 Dec 2010 21:40:41 +0000 Received: from [98.139.91.66] by nm13.bullet.mail.sp2.yahoo.com with NNFMP; 16 Dec 2010 21:40:32 -0000 Received: from [98.139.91.42] by tm6.bullet.mail.sp2.yahoo.com with NNFMP; 16 Dec 2010 21:40:32 -0000 Received: from [127.0.0.1] by omp1042.mail.sp2.yahoo.com with NNFMP; 16 Dec 2010 21:40:32 -0000 X-Yahoo-Newman-Id: 195105.29542.bm@omp1042.mail.sp2.yahoo.com Received: (qmail 94070 invoked from network); 16 Dec 2010 21:40:31 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btinternet.com; h=DKIM-Signature:Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=rdB6ISBQwVVlmUyus1eFI+YYVpwr8Drt1+d3aIUNo3vVsxQZMpdegbu0kOnhRTeFccHQ4XmRMhN8IOGFU3DYFsU9GSGDYhabHRBKR/fuVRInXmfw3hzDO+aeM5wNiXd+i07Ug4MlWryK09OW8R/PWQbvDUcxBcpFa7sj4QN6bcM= ; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=s1024; t=1292535631; bh=iiLvc7jYfMpMjhbevLD0GR+zznHcxR76Rew5BtkOeOg=; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=gI9PFcAHG1XvM9odDJ7Qf0NMezZBOassLb98OPiqo+Bk0g+T770XHmfH4xMNcL8aTzxl7ymqaLFGgzGSX0nsVu1qqicrZ1fwQx/VgTsGKI+qaQzPCSWYmwJeKenSFCfTE4+0SnbbbwZGmqDoNCFTQgdSKoZDBNNZEzeKGH0b7ac= Received: from lindavideo (ken.h.wright@86.162.64.127 with login) by smtp139.mail.mud.yahoo.com with SMTP; 16 Dec 2010 13:40:31 -0800 PST X-Yahoo-SMTP: 9Y6mUHuswBAgnrOsukIiNdFDf95uy_Dz34nY1hlg2liKgYD952sjbg-- X-YMail-OSG: umjler8VM1mHEyQAg8riUJS1FfdlwqA2JbF3Na_Y29noJ10 YVgvnkWY1waXBFWxxXGpKLarRRpL.HrRPO_GO2gWzIs4C6M.Jd6n7jkliBkR Ws.9x3GVLfGFWzqoEkQS4WNSFi8_eDvsiUMSRqtVv3YEBou8IpiTqvW5aVwV Brn4I09swv_hAS4UGuLg1KJtcgdIFZ9g3hRjz.iMtW9iKnIYR4lFQEDHHZNA HRmuB5jMYzxRbXxymqJ8tkNMdFkgaSGPE_LHCCQDfSaPmDUr5C66POhe_jgZ mtX88wlJ.quo6Z4Kh750BzybZfk3MftNvFLxUyHPGdDpECpR61PdpOsn8IM9 IBRcwTFL372EFCt2eF3MBY1.2hfZZuREBlhTlHPjuKjFiy_plGQ-- X-Yahoo-Newman-Property: ymail-3 Message-ID: <3EFB500A97ED483EA1547406C13F018E@lindavideo> From: "Ken" To: References: <005201cb9d61$8bdf3200$0201a8c0@Clemens04> <061B7DFBCF9048E9A7F715A530E1EE96@lindavideo> <00b901cb9d68$551bdc80$0201a8c0@Clemens04> Date: Thu, 16 Dec 2010 21:40:28 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5994 DomainKey-Status: good (testing) X-Spam-Score: 3.4 (+++) X-Spam-Report: autolearn=disabled,FORGED_MUA_OUTLOOK=3.36,HTML_MESSAGE=0.001,UNPARSEABLE_RELAY=0.001 Subject: LF: Re: Re: Re: Re: Sound Card mic Impedance Content-Type: multipart/alternative; boundary="----=_NextPart_000_009B_01CB9D69.DB53F2F0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.1 required=5.0 tests=FORGED_MUA_OUTLOOK,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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m214.1 ; domain : btinternet.com DKIM : fail x-aol-sid: 3039ac1d408d4d0a87861476 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_009B_01CB9D69.DB53F2F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Clemens. Dont forget I am trying to attenuate an unwanted incoming antenna rf= voltage. 73. Ken. M0KHW=20 ----- Original Message -----=20 From: Clemens Paul=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, December 16, 2010 9:29 PM Subject: LF: Re: Re: Re: Sound Card mic Impedance The 50-Ohm-termination at the output of the LP filter represents a 50-Ohm-*source* which is looking into the input impedance of the sou= ndcard. Hence the gross (power-)mismatch (SWR 80). For such high impedances at vlf (=3Daudio) frequencies voltage matching would be much more efficient. 73 Clemens DL4RAJ ----- Original Message -----=20 From: Ken=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, December 16, 2010 10:04 PM Subject: LF: Re: Re: Sound Card mic Impedance Hi Clements. Are you sure, shunting a 50 ohm resistor with 4k ohms reduces it= down to 49.38 ohms or am I missing something?. 73. Ken M0KHW=20 ----- Original Message -----=20 From: Clemens Paul=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, December 16, 2010 8:40 PM Subject: LF: Re: Sound Card mic Impedance Ken, >I am doing a Low Pass Filter to use with Winrad, F1, 20kHz, F2= , 30 kHz, 100kHz -80 dB (theoretical) with a >characteristic impedance= of 50 ohms, with this high input impedance I can locate the filter ve= ry close to the sound >card mic input and terminate the filter output= with a 50 ohm resistor. Assuming 4kOhm input impedance of the soundcard this will cause= a mismatch loss of around 13dB (95% loss) which may or may not cause concern dep= ending of the signal level of your antenna. 73 Clemens DL4RAJ ----- Original Message -----=20 From: Ken=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, December 16, 2010 9:06 PM Subject: LF: Sound Card mic Impedance Thank you all LFs. Thank you for all the info that you sent me, it looks they can= be anything from 4k ohms upwards, this is ok for me, I am doing a Lo= w Pass Filter to use with Winrad, F1, 20kHz, F2, 30 kHz, 100kHz -80 dB= (theoretical) with a characteristic impedance of 50 ohms, with this= high input impedance I can locate the filter very close to the sound= card mic input and terminate the filter output with a 50 ohm resistor= . Hopefully this will eliminate the BC intermod I was experiencing whe= n trying to receive Chris G3XIZ the other day. 73 Ken M0KHW I091TV=20 ------=_NextPart_000_009B_01CB9D69.DB53F2F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Clemens.
Dont forget I am trying to attenuate= an unwanted=20 incoming antenna rf voltage.
 
73.
Ken.
M0KHW 
----- Original Message -----
Sent: Thursday, December 16,= 2010 9:29=20 PM
Subject: LF: Re: Re: Re: Soun= d Card mic=20 Impedance

The 50-Ohm-termination at the outpu= t of the LP=20 filter represents a
50-Ohm-*source*=20 which is looking into the input impedance of the soundcard.
Hence the gross (power-)mismatch (S= WR=20 80).
For such high impedances at vl= f=20 (=3Daudio) frequencies
voltage matching would be much= more=20 efficient.
 
73
Clemens
DL4RAJ
 
 
----- Original Message -----
From:=20 Ken
Sent: Thursday, December 16= , 2010 10:04=20 PM
Subject: LF: Re: Re: Sound= Card mic=20 Impedance

Hi Clements.
Are you sure, shunting a 50 ohm= resistor with=20 4k ohms reduces it down to 49.38 ohms or am I missing=20 something?.
73.
Ken
M0KHW 
----- Original Message -----
From:=20 Clemens= Paul
Sent: Thursday, December= 16, 2010=20 8:40 PM
Subject: LF: Re: Sound Ca= rd mic=20 Impedance

Ken,
 
>I am doing  a Low Pass= Filter to use=20 with Winrad, F1, 20kHz, F2, 30 kHz, 100kHz -80 dB (theoretical)&= nbsp;with=20 a >characteristic impedance of 50 ohms, with this high input= =20 impedance I can locate the filter very close to the so= und=20 >card mic input and terminate the filter output with a 50 ohm= =20 resistor.
 
Assuming 4kOhm input impedance= of the=20 soundcard this will cause a mismatch loss
of around 13dB (95% loss) which= may or=20 may not cause concern depending of the signal=20 level of
your antenna.
 
 
73
Clemens
DL4RAJ<= /DIV>
----- Original Message -----=
From:=20 Ken
Sent: Thursday, Decembe= r 16, 2010=20 9:06 PM
Subject: LF: Sound Card= mic=20 Impedance

Thank you all LFs.
Thank you for all the info th= at you sent=20 me, it looks they can be anything from 4k ohms upwards, this= is ok for=20 me, I am doing  a Low Pass Filter to use with Winrad, F1,= 20kHz,=20 F2, 30 kHz, 100kHz -80 dB (theoretical) with a characteri= stic=20 impedance of 50 ohms, with this high input impedance I=20 can locate the filter very close to the sound card mic in= put and=20 terminate the filter output with a 50 ohm resistor. Hopef= ully this=20 will eliminate the BC intermod I was experiencing when trying= to receive=20 Chris G3XIZ the other day.
 
73
Ken
M0KHW  =20 I091TV 
=
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