X-GM-THRID: 1239849414365398926 X-Gmail-Labels: rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.78.172.10 with SMTP id u10cs452690hue; Thu, 21 Jun 2007 06:01:37 -0700 (PDT) Received: by 10.78.193.5 with SMTP id q5mr921836huf.1182430897636; Thu, 21 Jun 2007 06:01:37 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id g17si1084963nfd.2007.06.21.06.01.31; Thu, 21 Jun 2007 06:01:37 -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 1I1M9Q-0007X5-42 for rs_out_1@blacksheep.org; Thu, 21 Jun 2007 13:52:40 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1I1M9P-0007Ww-Cc for rsgb_lf_group@blacksheep.org; Thu, 21 Jun 2007 13:52:39 +0100 Received: from anchor-post-32.mail.demon.net ([194.217.242.90]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1I1M9O-0001mc-6V for rsgb_lf_group@blacksheep.org; Thu, 21 Jun 2007 13:52:39 +0100 Received: from dyn-62-56-125-190.dslaccess.co.uk ([62.56.125.190] helo=Tom) by anchor-post-32.mail.demon.net with esmtpa (AUTH telemetry) (Exim 4.42) id 1I1M9G-000Ns8-7i for rsgb_lf_group@blacksheep.org; Thu, 21 Jun 2007 12:52:35 +0000 Message-ID: <012601c7b403$0fbd3c30$be7d383e@Tom> From: "Tom Boucher" To: References: <062020072228.467.4679A9F000059E24000001D322058891160B97010D0A020E06979D0E03@comcast.net> <001801c7b392$de27dce0$0300a8c0@lark> <00c701c7b3d8$e0ff8b20$be7d383e@Tom> Date: Thu, 21 Jun 2007 13:52:42 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 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="----=_NextPart_000_0123_01C7B40B.703FAE50" 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_20_30,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: 1096 This is a multi-part message in MIME format. ------=_NextPart_000_0123_01C7B40B.703FAE50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The way I look at it Andy, is that the coax fed dipole is an un-balanced = system, so I had two antennas in parallel, each resonant on a slightly = different frequency. I bet if I had used twin balanced feeder, the = problem would not have occurred. Tom G3OLB ----- Original Message -----=20 From: Andy Talbot=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, June 21, 2007 9:38 AM Subject: Re: LF: Re: Re: LF Vertical Antennas problem... 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=20 Andy G4JNT www.scrbg.org/g4jnt =20 On 21/06/07, Tom Boucher wrote:=20 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=20 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: Sent: Thursday, June 21, 2007 12:29 AM Subject: LF: Re: LF Vertical Antennas problem...=20 > 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=20 > 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=20 > disconnected. > > Good Luck with it > Cheers de Alan G3NYK > > ----- Original Message ----- > From: > To: rsgb lf reflector < rsgb_lf_group@blacksheep.org>; rsgb lf = reflector > > Sent: 20 June 2007 23:28=20 > 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=20 > 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=20 > 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=20 > antenna > resonated properly. Any thoughts? >> >> >> -- >> 73 Warren K2ORS/WD2XGJ/WD2XSH/23/WE2XEB/2 >> FN42hi >> http://www.w4dex.com/wd2xgj.htm >> > > ------=_NextPart_000_0123_01C7B40B.703FAE50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The way I look at it Andy, is that the = coax fed=20 dipole is an un-balanced system, so I had two antennas in parallel, each = resonant on a slightly different frequency. I bet if I had used twin = balanced=20 feeder, the problem would not have occurred.
 
Tom G3OLB
----- Original Message -----
From:=20 Andy Talbot
Sent: Thursday, June 21, 2007 = 9:38=20 AM
Subject: Re: LF: Re: Re: LF = Vertical=20 Antennas problem...

It would. The Hi-Q quarter wave resonator formed by the = shorted=20 coax, interacting with the reactances of the antenna could cause all = sorts of=20 issues.  Compre this situation with the parallel and series=20 resonances of a crystal
 
Andy  G4JNT


 
On 21/06/07, Tom=20 Boucher <tom@telemetry.demon.co.uk&g= t;=20 wrote:=20
Warren

I=20 also had a strange effect when strapping a coax fed 80m dipole at=20 ground
level for use as a 160m 'TEE'. It appeared to show 2 = resonant=20 frequencies a
few Khz apart. When I strapped the feeder at the = top as=20 well as the bottom
of the feeder, all was OK!
73
Tom=20 G3OLB

----- Original Message -----
From: "Alan Melia" = <=20 alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org= >
Sent:=20 Thursday, June 21, 2007 12:29 AM
Subject: LF: Re: LF Vertical = Antennas=20 problem...


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



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