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[195.171.43.25]) by mx.google.com with ESMTP id v4si5636251wja.101.2013.11.08.14.12.38 for ; Fri, 08 Nov 2013 14:12:38 -0800 (PST) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1VetpD-0000kB-0X for rs_out_1@blacksheep.org; Fri, 08 Nov 2013 21:42:43 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VetpC-0000k2-3h for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2013 21:42:42 +0000 Received: from rhcavuit02.kulnet.kuleuven.be ([134.58.240.130] helo=cavuit02.kulnet.kuleuven.be) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Vetp9-0002zk-Fi for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2013 21:42:41 +0000 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: B5018128045.A4C90 X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-1.cc.kuleuven.be (icts-p-smtps-1e.kulnet.kuleuven.be [134.58.240.33]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id B5018128045 for ; Fri, 8 Nov 2013 22:42:31 +0100 (CET) Received: from ICTS-S-HUB3.luna.kuleuven.be (icts-s-hub3.luna.kuleuven.be [10.112.9.17]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by icts-p-smtps-1.cc.kuleuven.be (Postfix) with ESMTPS id B1B194042 for ; Fri, 8 Nov 2013 22:42:25 +0100 (CET) Received: from ICTS-S-MBX1.luna.kuleuven.be ([fe80::edaf:341f:90e:f70e]) by ICTS-S-HUB3.luna.kuleuven.be ([fe80::a470:76b3:406d:2b1a%27]) with mapi id 14.03.0158.001; Fri, 8 Nov 2013 22:42:25 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Thread-Topic: LF: remote antenna tuning Thread-Index: AQHO3HCUCD1oahz2q0ikAFZZ4yK07pobS52AgAASlqCAABILgIAAKgUAgAADwoCAADSULIAABBoo Date: Fri, 8 Nov 2013 21:42:24 +0000 Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAE@ICTS-S-MBX1.luna.kuleuven.be> References: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5@ICTS-S-MBX2.luna.kuleuven.be>,<527CEE11.8070509@iup.uni-heidelberg.de> <7E7DFBB4D102A04DB5ADC88D66628A4A0FC98037@ICTS-S-MBX1.luna.kuleuven.be> <527D0CCB.6090208@iup.uni-heidelberg.de> <527D300A.7000909@aol.com> <527D3331.7080109@iup.uni-heidelberg.de>,<9BE105EBAA5D429D8A7C1F8AE8B2FB65@gnat> In-Reply-To: <9BE105EBAA5D429D8A7C1F8AE8B2FB65@gnat> Accept-Language: nl-BE, en-GB, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.112.13.13] MIME-Version: 1.0 X-HELO-Warning: Remote host 134.58.240.130 (rhcavuit02.kulnet.kuleuven.be) used invalid HELO/EHLO cavuit02.kulnet.kuleuven.be - verification failed X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hello Alan, Stefan, in my mail I just wanted to point out that maximum current at the TX output (one end of the coax cable) not coincidences with maximum current at the antenna (other end of the coax cable). [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [134.58.240.130 listed in list.dnswl.org] -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 1b85b97af56c2ce8b6be9bd6ca70127d Subject: RE: LF: remote antenna tuning Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAEICTSSMBX1lunaku_" 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, TO_ADDRESS_EQ_REAL 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: 1758 --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAEICTSSMBX1lunaku_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Alan, Stefan, in my mail I just wanted to point out that maximum current at the TX output= (one end of the coax cable) not coincidences with maximum current at the = antenna (other end of the coax cable). So tuning (adjusting the loading coil) for maximum current at the TX will n= ot result in maximum ERP. I am aware that a transmission line can transform the antenna impedance, bu= t at first I was suprised that it happend so significant with a short (comp= ared to the wavelength) cable. This evening I did some simulations using SIMetrix (http://www.simetrix.co.= uk/) and this confirmed more or less my measurements. For clearity: at this moment the Rloss (+ Rrad) is about 60 Ohm and I did n= ot care to match it to 50 Ohm. The only tuning was done with the loading co= il (cancel out any reactive part of the antenna impedance). 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org= ] namens Alan Melia [alan.melia@btinternet.com] Verzonden: vrijdag 8 november 2013 20:35 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: remote antenna tuning Rik, Stefan, I follow your points but there would seem to be something stra= nge in Rik's antenna or his appreciation of what/how its working. Contrary to an earlier assertion, the antenna current flowing through Rrad = generates the radiated power, so lower current, if Rrad doesnt change, MUST= mean lower tranmitted power. It matters not that the SWR is unity. A unity= SWR indication at the transmitter says that the impedance at the end of th= e coax is 50ohms, but it does not necessarily indicate the the the antenna = is resonant i.e the inherent capacitance of a short antenna totally compens= ated by the loading inductance. If we assume that Rrad+Rloss does not chang= e across the band the matching transformer should transform the value of Rr= ad+Rloss to 50 ohms across all the band. The coax will now be matched and w= ill present 50ohms at the shack end. If this does not happen I would be inc= lined to suspect currents induced in the coax braid. SWR indicators can eas= ily be confused by induced braid currents......could this be the cause of R= iks strange effects? This might be a function of having a "better" ground i= n the shack than at the base of the antenna. Alan G3NYK ----- Original Message ----- From: Stefan Sch=E4fer To: rsgb_lf_group@blacksheep.org Sent: Friday, November 08, 2013 6:53 PM Subject: Re: LF: remote antenna tuning Oh yes, or, a phase meter (M0BMU) and a battery operated variometer motor. = Without an additional cable to the shack. Then the SWR meter in the shack c= onfirms that everything is fine. 73, Stefan Am 08.11.2013 19:40, schrieb pat: Hi All, A suggestion: battery operated tuning device at antenna end and "wireless" = link back to shack. Wireless can operate at a non-interfering frequncy (HF/= VHF/UHF/Optical). 73 On 08/11/13 16:09, Stefan Sch=E4fer wrote: Hi Rik, Am 08.11.2013 16:06, schrieb Rik Strobbe: Hi Stefan, remote tuning of the loading should be done by optimizing SWR (at the TX), = not for maximum RF current. If one keeps that in mind there is no problem. ...which is in agreement with what i said. But once you have matched your antenna to 50 Ohm on resonance and you can o= nly vary the reactive part of the antennas impedance (after doing QSY), the= n you will get the maximum antenna current at best SWR (assuming that Rrad+= Rloss is constant which is not to far from reality). I am not sure if I will keep the remote variometer tuning. It needs some ex= tra wires to the loading coil and I am not sure how long the small DC motor= will function properly with all the rain and frost coming up. Here it holds since more than 2 years for LF now.. 73, Stefan -- 73 de pat g4gvw es gd dx qth nr Felixstowe East Coast UK --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAEICTSSMBX1lunaku_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hello Alan, Stefan,

 

in my mail I just wanted to point out that maximum current at the T= X output (one end of the coax cable)  not coincidences with maximum cu= rrent at the antenna (other end of the coax cable).

So tuning (adjusting the loading coil) for maximum current at the TX wil= l not result in maximum ERP.

 

I am aware that a transmission line can transform the antenna impedance,= but at first I was suprised that it happend so significant with a short (c= ompared to the wavelength) cable.

This evening I did some simulations using SIMetrix (http://www.simetrix.co.uk/) and this confi= rmed more or less my measurements.

 

For clearity: at this moment the Rloss (+ Rrad) is about 60 Ohm and = I did not care to match it to 50 Ohm. The only tuning was done with the loa= ding coil (cancel out any reactive part of the antenna impedance).

 

73, Rik  ON7YD - OR7T

Van: owner-rsgb_lf_group@blacksheep.org [o= wner-rsgb_lf_group@blacksheep.org] namens Alan Melia [alan.melia@btinternet= .com]
Verzonden: vrijdag 8 november 2013 20:35
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: remote antenna tuning

Rik, Stefan, I follow your points but = there would seem to be something strange in Rik's antenna or his appreciati= on of what/how its working.
 
Contrary to an earlier assertion, the = antenna current flowing through Rrad generates the radiated power, so lower= current, if Rrad doesnt change, MUST mean lower tranmitted power. It = matters not that the SWR is unity. A unity SWR indication at the transmitter says that the impedance at the end of th= e coax is 50ohms, but it does not necessarily indicate the the the antenna = is resonant i.e the inherent capacitance of a short antenna totally compens= ated by the loading inductance. If we assume that Rrad+Rloss does not change across the band the match= ing transformer should transform the value of Rrad+Rloss to 50 ohms acr= oss all the band. The coax will now be matched and will present 50ohms at t= he shack end. If this does not happen I would be inclined to suspect currents induced in the coax braid. SWR indic= ators can easily be confused by induced braid currents......could this= be the cause of Riks strange effects? This might be a function of having a= "better" ground in the shack than at the base of the antenna.
 
Alan
G3NYK
 
----- Original Message -----
Sent: Friday, November 08, 2013 6:53= PM
Subject: Re: LF: remote antenna tuni= ng

Oh yes, or, a phase meter (M0BMU) and a battery operated variometer motor. = Without an additional cable to the shack. Then the SWR meter in the shack c= onfirms that everything is fine.

73, Stefan

Am 08.11.2013 19:40, schrieb pat:
Hi All,

A suggestion: battery operated tuning device at antenna end and "wirel= ess" link back to shack. Wireless can operate at a non-interfering fre= quncy (HF/VHF/UHF/Optical).

73






On 08/11/13 16:09, Stefan Sch=E4fer wrote:
Hi Rik,

Am 08.11.2013 16:06, schrieb Rik Strobbe:

Hi Stefan,

 

remote tuning of the loading should be done&nbs= p;by optimizing SWR (at the TX), not for maximum R= F current.

If one keeps that in mind there is no prob= lem.

...which is in agreement with what i said.
But once you have matched your antenna to 50 Ohm on resonance and you can o= nly vary the reactive part of the antennas impedance (after doing QSY), the= n you will get the maximum antenna current at best SWR (assuming that Rrad&= #43;Rloss is constant which is not to far from reality).

I am not sure if I will keep the remote&nb= sp;variometer tuning. It needs some extra wires to the&= nbsp;loading coil and I am not sure how long the&n= bsp;small DC motor will function properly with all= the rain and frost coming up.

Here it holds since more than 2 years for LF now..

73, Stefan



--=20
73 de pat g4gvw
es gd dx
qth nr Felixstowe
East Coast UK
--_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAEICTSSMBX1lunaku_--