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[195.171.43.25]) by mx.google.com with ESMTP id nd3si2038400wic.21.2013.11.08.15.57.37 for ; Fri, 08 Nov 2013 15:57:38 -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 1VevNz-00019B-Qp for rs_out_1@blacksheep.org; Fri, 08 Nov 2013 23:22:43 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VevNz-000192-0X for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2013 23:22:43 +0000 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1VevNw-0003K6-DK for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2013 23:22:41 +0000 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id rA8NMdfJ021566 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sat, 9 Nov 2013 00:22:39 +0100 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id rA8NMdxO002427 for ; Sat, 9 Nov 2013 00:22:39 +0100 Message-ID: <527D723A.50707@iup.uni-heidelberg.de> Date: Sat, 09 Nov 2013 00:22:34 +0100 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org 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> <7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAE@ICTS-S-MBX1.luna.kuleuven.be> In-Reply-To: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC99DAE@ICTS-S-MBX1.luna.kuleuven.be> X-Spam-Score: -2.3 (--) 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 Rik, OK. And how did you connect the cable to the coil? Just in series or by using a transformer or by making a tap? And how do you measure the antenna current (what type of meter)? 73, Stefan [...] Content analysis details: (-2.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [129.206.210.211 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: 962f2daa83886715a5d650b1c8628c8a Subject: Re: LF: remote antenna tuning Content-Type: multipart/alternative; boundary="------------090304020703050204080201" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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: 3444 This is a multi-part message in MIME format. --------------090304020703050204080201 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id rA8NMdfJ021566 Hello Rik, OK. And how did you connect the cable to the coil? Just in series or by=20 using a transformer or by making a tap? And how do you measure the=20 antenna current (what type of meter)? 73, Stefan Am 08.11.2013 22:42, schrieb Rik Strobbe: > > Hello Alan, Stefan, > > in my mail I just wanted to point out that maximum current at the TX=20 > output (one end of the coax cable) not coincidences with maximum=20 > current at the antenna (other end of the coax cable). > > So tuning (adjusting the loading coil) for maximum current at the TX=20 > will not result in maximum ERP. > > I am aware that a transmission line can transform the antenna=20 > impedance, but at first I was suprised that it happend so significant=20 > with a short (compared to the wavelength) cable. > > This evening I did some simulations using SIMetrix=20 > (http://www.simetrix.co.uk/) and this confirmed more or less my=20 > measurements. > > For clearity: at this moment the Rloss (+ Rrad) is about 60 Ohm and I=20 > did not care to match it to 50 Ohm. The only tuning was done with the=20 > loading coil (cancel out any reactive part of the antenna impedance). > > 73, Rik ON7YD - OR7T > > -----------------------------------------------------------------------= - > *Van:* owner-rsgb_lf_group@blacksheep.org=20 > [owner-rsgb_lf_group@blacksheep.org] namens Alan Melia=20 > [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=20 > strange in Rik's antenna or his appreciation of what/how its working. > Contrary to an earlier assertion, the antenna current flowing through=20 > Rrad generates the radiated power, so lower current, if Rrad doesnt=20 > change, MUST mean lower tranmitted power. It matters not that the SWR=20 > is unity. A unity SWR indication at the transmitter says that the=20 > impedance at the end of the coax is 50ohms, but it does not=20 > necessarily indicate the the the antenna is resonant i.e the inherent=20 > capacitance of a short antenna totally compensated by the loading=20 > inductance. If we assume that Rrad+Rloss does not change across the=20 > band the matching transformer should transform the value of Rrad+Rloss=20 > to 50 ohms across all the band. The coax will now be matched and will=20 > present 50ohms at the shack end. If this does not happen I would be=20 > inclined to suspect currents induced in the coax braid. SWR=20 > indicators can easily be confused by induced braid currents......could=20 > this be the cause of Riks strange effects? This might be a function of=20 > having a "better" ground in 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 confirms 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 only vary the reactive part of the antennas >>> impedance (after doing QSY), then 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 extra 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 >>> >> >> >> --=20 >> 73 de pat g4gvw >> es gd dx >> qth nr Felixstowe >> East Coast UK > --------------090304020703050204080201 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hello Rik,

OK. And how did you connect the cable to the coil? Just in series or by using a transformer or by making a tap? And how do you measure the antenna current (what type of meter)?

73, Stefan




Am 08.11.2013 22:42, schrieb Rik Strobbe:

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 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 (compared 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 not care to match it to 50 Ohm. The only tuning was done with the loading coil (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 strange 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 the 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 compensated by the loading inductance. If we assume that Rrad+Rloss does not change across the band the matching transformer should transform the value of Rrad+Rloss to 50 ohms across all the band. The coax will now be matched and will present 50ohms at the shack end. If this does not happen I would be inclined to suspect currents induced in the coax braid. SWR indicators 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 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 confirms 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 Schäfer 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 only vary the reactive part of the antennas impedance (after doing QSY), then 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 extra 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
--------------090304020703050204080201--