X-GM-THRID: 1234888028149353688 X-Gmail-Labels: rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.35.22.5 with SMTP id z5cs319102pyi; Fri, 27 Apr 2007 06:56:54 -0700 (PDT) Received: by 10.67.89.6 with SMTP id r6mr2001476ugl.1177682213783; Fri, 27 Apr 2007 06:56:53 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id 72si969941ugb.2007.04.27.06.56.51; Fri, 27 Apr 2007 06:56:53 -0700 (PDT) Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1HhQsi-0005RA-Qx for rs_out_1@blacksheep.org; Fri, 27 Apr 2007 14:53:04 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1HhQsi-0005R1-A8 for rsgb_lf_group@blacksheep.org; Fri, 27 Apr 2007 14:53:04 +0100 Received: from smtp812.mail.ird.yahoo.com ([217.146.188.72]) by relay3.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1HhQsh-0001FY-FI for rsgb_lf_group@blacksheep.org; Fri, 27 Apr 2007 14:53:04 +0100 Received: (qmail 55118 invoked from network); 27 Apr 2007 13:52:48 -0000 Received: from unknown (HELO MJUSonyLaptop) (m.j.underhill@btinternet.com@86.142.235.125 with login) by smtp812.mail.ird.yahoo.com with SMTP; 27 Apr 2007 13:52:47 -0000 X-YMail-OSG: nh_9p5cVM1nFWWjlYL8ZhCDUZtlsbkDKYDzppFm4Z93hFII_VYhuZ6722sN3e339sH1nOLbp5A-- From: "Mike Underhill" To: Date: Fri, 27 Apr 2007 14:53:04 +0100 Message-ID: <001701c788d3$612266f0$6405a8c0@MJUSonyLaptop> MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6822 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 In-Reply-To: Thread-Index: AceIwLJP6Bu/ihvVQlSQVCcNLuIYyQAEaQsw Importance: Normal X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: RE: Filter expert needed - Mystery of the lost real zero. Content-Type: multipart/alternative; boundary="----=_NextPart_000_0018_01C788DB.C2E6CEF0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.2 required=5.0 tests=HTML_60_70, HTML_FONTCOLOR_UNKNOWN,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 Status: O X-Status: X-Keywords: X-UID: 2010 This is a multi-part message in MIME format. ------=_NextPart_000_0018_01C788DB.C2E6CEF0 Content-Type: text/plain; charset="windows-1250" Content-Transfer-Encoding: quoted-printable Andy=20 =20 A correction: I should have said =91in series with=92 and not = =91across=92. So that my post should read: =20 =93For a second zero on the HF side try an inductor =91in series with=92 = the =91zero=92 capacitor. The trouble is that it will have to have the same reactance as this 1.5p capacitor and that may not be easily realisable = in practice. The inductor could also go between resonators 1 and 3 or 3 = and 5 I think. If the inductor value is too high you can use a small = =91link=92 coil on each of the resonators to be inductively coupled and connect these by = a pair of twisted wires. Getting the coupling right can be fiddly. You = can get another LF zero rather than the wanted HF zero, I think, if you get = the phasing wrong.=94 . =20 =20 I hope this helps but as I said it is some time since I taught this = stuff! Good luck. =20 Mike =96 G3LHZ =20 =20 =20 No virus found in this outgoing message. Checked by AVG Free Edition.=20 Version: 7.5.463 / Virus Database: 269.6.1/777 - Release Date: = 26/04/2007 15:23 =20 ------=_NextPart_000_0018_01C788DB.C2E6CEF0 Content-Type: text/html; charset="windows-1250" Content-Transfer-Encoding: quoted-printable

Andy

 

A correction: I should have said = =91in series with=92 and not =91across=92.  So that my post should read:

 

=93For a second zero on the HF side try an inductor =91in series with=92 the =91zero=92 capacitor.  The trouble is that it will have to have the same = reactance as this 1.5p capacitor and that may not be easily realisable in = practice.  The inductor could also go between resonators 1 and 3 or 3 and 5 I = think.  If the inductor value is too high you can use a small =91link=92 coil on each of the resonators to be inductively coupled and connect these by = a pair of twisted wires.  Getting the coupling right can be fiddly. You = can get another LF zero rather than the wanted HF zero, I think, if you get the = phasing wrong.=94  . 

 

I hope this helps but as I said it = is some time since I taught this stuff!  Good luck.

 

Mike =96 G3LHZ

 

 

 


No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.463 / Virus Database: 269.6.1/777 - Release Date: = 26/04/2007 15:23

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