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[195.171.43.25]) by mx.google.com with ESMTP id di12si995775wid.48.2013.11.08.05.42.37 for ; Fri, 08 Nov 2013 05:42:38 -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 1VeljV-0006jP-1p for rs_out_1@blacksheep.org; Fri, 08 Nov 2013 13:04:17 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VeljU-0006jA-Fw for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2013 13:04:16 +0000 Received: from rhcavuit01.kulnet.kuleuven.be ([134.58.240.129] helo=cavuit01.kulnet.kuleuven.be) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1VeljS-0000vE-Eu for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2013 13:04:15 +0000 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: 501B5138046.A66AA 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 cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id 501B5138046; Fri, 8 Nov 2013 14:03:59 +0100 (CET) Received: from ICTS-S-HUB2.luna.kuleuven.be (icts-s-hub2.luna.kuleuven.be [10.112.9.16]) (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 23D144052; Fri, 8 Nov 2013 14:03:57 +0100 (CET) Received: from ICTS-S-MBX2.luna.kuleuven.be ([fe80::9cd:c392:50ae:540f]) by ICTS-S-HUB2.luna.kuleuven.be ([fe80::8559:ca7c:e195:e15d%26]) with mapi id 14.03.0158.001; Fri, 8 Nov 2013 14:03:56 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" , "rsgb_lf_group@yahoogroups.co.uk" Thread-Topic: remote antenna tuning Thread-Index: AQHO3HCUCD1oahz2q0ikAFZZ4yK07g== Date: Fri, 8 Nov 2013 13:03:56 +0000 Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5@ICTS-S-MBX2.luna.kuleuven.be> Accept-Language: nl-BE, en-GB, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.112.13.14] MIME-Version: 1.0 X-HELO-Warning: Remote host 134.58.240.129 (rhcavuit01.kulnet.kuleuven.be) used invalid HELO/EHLO cavuit01.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: Dear all, I want to share an experience hat might be interesting for others too: After moving from 501-504kHz to 472-479kHz I noticed that even my lossy antenna needs retuning within the band. [...] 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 [134.58.240.129 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: 3df6620ae1cf83b986cf2fc02407da16 Subject: LF: remote antenna tuning Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5ICTSSMBX2lunaku_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_60_70,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: 1287 --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5ICTSSMBX2lunaku_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dear all, I want to share an experience hat might be interesting for others too: After moving from 501-504kHz to 472-479kHz I noticed that even my lossy ant= enna needs retuning within the band. As it is not very convenient to do that at the loading coil (abt 30m from t= he house) I decided to install a small DC motor for remote tuning the loadi= ng coil. Tuning can be done both at the TX (in the shack) and at the loadin= g coil. Between both is about 40m of coax cable. A first test done at the loading coil showed that it worked fine and I tune= d the antenna to maximum current (550 mA for 20W TX power) on 475 kHz (+/- = band mid). When I went into the shack and from there I tuned the antenna to maximum cu= rrent at the lower band end (472 kHz) I noticed 2 things: 1. The variation of the loading coil was much more than expected. 2. The maximum current (at the TX output) was 760 mA. Very strange. So I went back out to the loading coil to measure the antenna= current (leaving the remote tuning in the position for maximum current at = the TX). The current had dropped to 410 mA and I had to do some serious ret= uning to get it back to maximum (550 mA). Back in the shack I measured the RF current at the TX: also 550 mA (as it s= hould be). So despite the fact that the coax cable is merely 10% of the wavelength it = seriously affects remote tuning. I did some calculations and even with a sh= ort coax cable (10 m) this effect should be noticable. By the way: remote tuning can be done correctly by tuning for best SWR inst= ead of highest RF current at the TX output. 73, Rik ON7YD - OR7T --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC908D5ICTSSMBX2lunaku_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Dear all,

 

I want to share an experience hat&nb= sp;might be interesting for = ;others too:

 

After moving from=  501-504kHz to 472-479kHz I notic= ed that= even my lossy antenna needs&n= bsp;retuning within the band.

As it is not<= a> very conv= enient to do that<= /a> at the loading&nb= sp;coil (abt 30m from the house) I decided to install a small DC motor for remote tuning the loading= coil. Tun= ing can=  be done<= a> both at the TX (in the shack) and at the loading= coil. Between=  both is about 40m= of coax cable= .

A first test done= at the loading coil showed that it=  worked= fine and I tuned the antenna to ma= ximum current (550 mA for 20W&= nbsp;TX power) on<= /a> 475 kHz (+/- band mid).

When I went into<= /a> the shack = and from there I tuned the antenna to maximum current at = the lower band end (472 kHz) I = ;noticed 2 things:

1. The variation of the&nbs= p;loading coil= was much more t= han expected= .

2. The maximum current (at the&n= bsp;TX output) was 760 mA.

Very strange. So I went back out= to the loading coil= to measure the antenna current (leaving the remote tuning in the position for maximum current at the TX). The current had dropped to 410 mA and I h= ad to do some serious retuning to get it back to maximum (550 mA).

Back in the shack I measure= d the RF current at the TX: also 550 mA (as it should be).

So despite<= a> the fact that= the coax<= a> cable is merely= 10% of the wavelength it seriously affects remote= tuning. I did some calculations and e= ven with a short coax cable (10 m) this effect should<= /a> be&= nbsp;noticable.

 

By the way: remote tuning&nbs= p;can be done correctly by<= a> tuning<= a> for best SWR<= /a> instead of highest RF current at the&= nbsp;TX output.

 

73, Rik  ON7YD - OR7T

 

 

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