X-GM-THRID: 1239849414365398926 X-Gmail-Labels: rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.78.172.10 with SMTP id u10cs442476hue; Thu, 21 Jun 2007 01:41:25 -0700 (PDT) Received: by 10.65.224.11 with SMTP id b11mr3019013qbr.1182415284467; Thu, 21 Jun 2007 01:41:24 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id f7si7859528nfh.2007.06.21.01.41.18; Thu, 21 Jun 2007 01:41:24 -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) DomainKey-Status: good (test mode) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1I1IBH-0006PI-4q for rs_out_1@blacksheep.org; Thu, 21 Jun 2007 09:38:19 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1I1IBG-0006P9-CL for rsgb_lf_group@blacksheep.org; Thu, 21 Jun 2007 09:38:18 +0100 Received: from wx-out-0506.google.com ([66.249.82.231]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1I1IBE-0007eY-TA for rsgb_lf_group@blacksheep.org; Thu, 21 Jun 2007 09:38:18 +0100 Received: by wx-out-0506.google.com with SMTP id h26so409149wxd for ; Thu, 21 Jun 2007 01:38:13 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=googlemail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=sDpPg9++H2WEcSRnuY8QZFvlw2gZlkoabS8gI+HbVH3HSW7ZSmFekfAxU/U7AwBbXCxxSuB/FcfXIz/a05GMZz5QdpnkTL/Fi/YR7rEY9e7kL1YmCG92jTlE0bfTp7r2HUUwYixsTYYcMnKtqWmrJbwA042yxOSplOBygEf6E+o= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=A90YeJRNWBHtFzAezWwvhlNMKort9TI/yLh7YwAYRsQaeKVAFN6uMaYMk7+zBEz5K0y/npyJ52niOyH5YeB2oAZdt98Rp+inyzG/R22T9gQ3Ihvi6Yzyv+EZkJ82CvBhnSO0/wlPsfUGDECZXW2ZmgUBeUycazor9dggBLZeB48= Received: by 10.90.75.10 with SMTP id x10mr1302879aga.1182415093420; Thu, 21 Jun 2007 01:38:13 -0700 (PDT) Received: by 10.90.31.17 with HTTP; Thu, 21 Jun 2007 01:38:13 -0700 (PDT) Message-ID: Date: Thu, 21 Jun 2007 09:38:13 +0100 From: "Andy Talbot" To: rsgb_lf_group@blacksheep.org In-Reply-To: <00c701c7b3d8$e0ff8b20$be7d383e@Tom> MIME-Version: 1.0 References: <062020072228.467.4679A9F000059E24000001D322058891160B97010D0A020E06979D0E03@comcast.net> <001801c7b392$de27dce0$0300a8c0@lark> <00c701c7b3d8$e0ff8b20$be7d383e@Tom> DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Re: Re: LF Vertical Antennas problem... Content-Type: multipart/alternative; boundary="----=_Part_30589_22255990.1182415093378" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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: 1097 ------=_Part_30589_22255990.1182415093378 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline It would. The Hi-Q quarter wave resonator formed by the shorted coax, interacting with the reactances of the antenna could cause all sorts of issues. Compre this situation with the parallel and series resonances of a crystal Andy G4JNT www.scrbg.org/g4jnt On 21/06/07, Tom Boucher wrote: > > Warren > > I also had a strange effect when strapping a coax fed 80m dipole at ground > level for use as a 160m 'TEE'. It appeared to show 2 resonant frequencies > a > few Khz apart. When I strapped the feeder at the top as well as the bottom > of the feeder, all was OK! > 73 > Tom G3OLB > > ----- Original Message ----- > From: "Alan Melia" > To: > Sent: Thursday, June 21, 2007 12:29 AM > Subject: LF: Re: LF Vertical Antennas problem... > > > > Hi Warren that sounds familiar !! I think you are using covered wire, my > > guess is a break on one leg so that you do not have enough capacitance > to > > resonate with the original coils. A top-band dipole will still work > quite > > well with one leg disconnected. Can you leave out the loading coil and > > measure the resonance frequency of the wire T alone that might give some > > clues. I have had this effect when part of the top load comes > > disconnected. > > > > Good Luck with it > > Cheers de Alan G3NYK > > > > ----- Original Message ----- > > From: > > To: rsgb lf reflector ; rsgb lf reflector > > > > Sent: 20 June 2007 23:28 > > Subject: LF: LF Vertical Antennas problem... > > > > > >> Hello the list, > >> > >> I have in the past used my 160 meter dipole as a vertical "T" by > >> tying > > the feeders together and using a tapped loading coil to resonate and > match > > the antenna. I could get a perfect 50 ohm match in this manner and it > > radiated quite well - Hartmut copied my transmission running around 100 > > watts. I have also used the same setup on 500kHz with a different > loading > > coil successfully. > >> > >> Now I find that I cannot resonate the antenna - I can't eliminate > the > > reactance no matter what the setting of the tap or the coil. The best I > > can > > do is an swr of 1.7:1 and at least 40 ohms of reactance. I have tried > > changing coils and still the problem persists. If I do transmit this > way, > > my signal seems to be down at least 10dB below what it was when the > > antenna > > resonated properly. Any thoughts? > >> > >> > >> -- > >> 73 Warren K2ORS/WD2XGJ/WD2XSH/23/WE2XEB/2 > >> FN42hi > >> http://www.w4dex.com/wd2xgj.htm > >> > > > > > > > ------=_Part_30589_22255990.1182415093378 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline
It would. The Hi-Q quarter wave resonator formed by the shorted coax, interacting with the reactances of the antenna could cause all sorts of issues.  Compre this situation with the parallel and series resonances of a crystal
 
Andy  G4JNT


 
On 21/06/07, Tom Boucher <tom@telemetry.demon.co.uk> wrote:
Warren

I also had a strange effect when strapping a coax fed 80m dipole at ground
level for use as a 160m 'TEE'. It appeared to show 2 resonant frequencies a
few Khz apart. When I strapped the feeder at the top as well as the bottom
of the feeder, all was OK!
73
Tom G3OLB

----- Original Message -----
From: "Alan Melia" < alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, June 21, 2007 12:29 AM
Subject: LF: Re: LF Vertical Antennas problem...


> Hi Warren that sounds familiar !! I think you are using covered wire, my
> guess is a break on one leg so that you do not have enough capacitance to
> resonate with the original coils. A top-band dipole will still work quite
> well with one leg disconnected. Can you leave out the loading coil and
> measure the resonance frequency of the wire T alone that might give some
> clues. I have had this effect when part of the top load comes
> disconnected.
>
> Good Luck with it
> Cheers de Alan G3NYK
>
> ----- Original Message -----
> From: <k2ors@comcast.net>
> To: rsgb lf reflector < rsgb_lf_group@blacksheep.org>; rsgb lf reflector
> <rsgb_lf_group@blacksheep.org>
> Sent: 20 June 2007 23:28
> Subject: LF: LF Vertical Antennas problem...
>
>
>> Hello the list,
>>
>>     I have in the past used my 160 meter dipole as a vertical "T" by
>> tying
> the feeders together and using a tapped loading coil to resonate and match
> the antenna. I could get a perfect 50 ohm match in this manner and it
> radiated quite well - Hartmut copied my transmission running around 100
> watts. I have also used the same setup on 500kHz with a different loading
> coil successfully.
>>
>>    Now I find that I cannot resonate the antenna - I can't eliminate the
> reactance no matter what the setting of the tap or the coil. The best I
> can
> do is an swr of 1.7:1 and at least 40 ohms of reactance. I have tried
> changing coils and still the problem persists.  If I do transmit this way,
> my signal seems to be down at least 10dB below what it was when the
> antenna
> resonated properly. Any thoughts?
>>
>>
>> --
>> 73 Warren K2ORS/WD2XGJ/WD2XSH/23/WE2XEB/2
>> FN42hi
>> http://www.w4dex.com/wd2xgj.htm
>>
>
>



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