Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-me04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 743213800008F; Sat, 3 Mar 2012 20:35:50 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1S40Li-0003ap-7f for rs_out_1@blacksheep.org; Sun, 04 Mar 2012 01:34:58 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1S40Lh-0003ag-On for rsgb_lf_group@blacksheep.org; Sun, 04 Mar 2012 01:34:57 +0000 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1S40Lg-0008I2-9P for rsgb_lf_group@blacksheep.org; Sun, 04 Mar 2012 01:34:57 +0000 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id q241Ytr0002898 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sun, 4 Mar 2012 02:34:55 +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 q241YtRr017054 for ; Sun, 4 Mar 2012 02:34:55 +0100 Message-ID: <4F52C688.6000605@iup.uni-heidelberg.de> Date: Sun, 04 Mar 2012 02:34:00 +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: <12959492286D45E9BB24E80CE57644CD@AGB> <4F52C0BB.3010505@iup.uni-heidelberg.de> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Permissible QSY limits for 136 Content-Type: multipart/alternative; boundary="------------020509040104040006050209" 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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:459533920:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d608c4f52c6f614cb X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------020509040104040006050209 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id q241Ytr0002898 Am 04.03.2012 02:23, schrieb Graham: > Thanks' Stefan, . bit late in the night > 50 ? That's quite low ,/ /I was expecting much higher ? that's =20 > for a 'large' system ? Well if you assume a loss resistance of 50 Ohm and 470 pF for the=20 antenna then its about 50. OK, 470 pF is much. So then you have Q=3D100 if C is 235 pF ;-) > do you have a ball park figure for the max frequency change =20 > on that ? What kind of PA do you run? As long as it is no class E i would do some=20 careful tests, i.e. allow an offset and see what happens after some=20 minutes. However there can be overvoltage problems as well. > 1:1.5 > 5% reflected power , that would reduce the b/w again .. Reflected, eventually this is no problem since e.g. in a H bridge the=20 power is then not dissipated but pushed back into the capacitor again=20 (which has to deal with the higher voltages then). 73, Stefan > Tnx -G.. > > *From:* Stefan Sch=E4fer > *Sent:* Sunday, March 04, 2012 1:09 AM > *To:* rsgb_lf_group@blacksheep.org > *Subject:* Re: LF: Permissible QSY limits for 136 > > > Am 04.03.2012 02:01, schrieb Graham: >> Permissible QSY limits for 136 >> Q what is the average Q of a 136 Khz Ae system ? (back=20 >> garden + larger) > > Maybe arround 50. > >> Q What would the maximum acceptable change in frequency +/- =20 >> Fo before swr considerations became a problem , say 10% =20 >> reflected power 1 :2 swr ? .... > That depends strongly on the PA circuit. A class E is very critical. A=20 > H bridge has almost no problems at all (just lower output power then).=20 > I would stay below 1:1.5 if the output power is 70% or above. > > 73, Stefan > --------------020509040104040006050209 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit
Am 04.03.2012 02:23, schrieb Graham:
Thanks'  Stefan,  . bit  late in the  night 
 
50 ?  That's  quite  low ,  I was  expecting  much  higher  ? that's  for  a  'large'  system ?
Well if you assume a loss resistance of 50 Ohm and 470 pF for the antenna then its about 50.
OK, 470 pF is much. So then you have Q=100 if C is 235 pF ;-)


do  you  have  a  ball park figure  for the  max  frequency   change  on that  ?
What kind of PA do you run? As long as it is no class E i would do some careful tests, i.e. allow an offset and see what happens after some minutes. However there can be overvoltage problems as well.
 
1:1.5  >  5%  reflected  power , that  would  reduce the  b/w  again  ..
Reflected, eventually this is no problem since e.g. in a H bridge the power is then not dissipated but pushed back into the capacitor again (which has to deal with the higher voltages then).

73, Stefan

 
Tnx -G..

Sent: Sunday, March 04, 2012 1:09 AM
Subject: Re: LF: Permissible QSY limits for 136


Am 04.03.2012 02:01, schrieb Graham:
Permissible QSY limits for 136
 
Q what  is the  average  Q   of  a   136 Khz  Ae  system  ? (back garden  + larger)

Maybe arround 50.

 
Q What  would the  maximum  acceptable  change  in frequency   +/-  Fo   before  swr  considerations  became a problem , say   10%  reflected  power  1 :2  swr ? ....
That depends strongly on the PA circuit. A class E is very critical. A H bridge has almost no problems at all (just lower output power then). I would stay below 1:1.5 if the output power is 70% or above.

73, Stefan

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