Return-Path: Received: from mtain-dh11.r1000.mx.aol.com (mtain-dh11.r1000.mx.aol.com [172.29.65.31]) by air-mc02.mail.aol.com (v129.4) with ESMTP id MAILINMC021-a8d34c598086114; Wed, 04 Aug 2010 11:00:22 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dh11.r1000.mx.aol.com (Internet Inbound) with ESMTP id C985B380014CA; Wed, 4 Aug 2010 11:00:19 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OgfQd-0006UK-I8 for rs_out_1@blacksheep.org; Wed, 04 Aug 2010 15:58:47 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OgfQc-0006UB-TN for rsgb_lf_group@blacksheep.org; Wed, 04 Aug 2010 15:58:46 +0100 Received: from blu0-omc1-s8.blu0.hotmail.com ([65.55.116.19]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OgfQc-0002Sc-0v for rsgb_lf_group@blacksheep.org; Wed, 04 Aug 2010 15:58:46 +0100 Received: from BLU146-W33 ([65.55.116.7]) by blu0-omc1-s8.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 4 Aug 2010 07:58:39 -0700 Message-ID: X-Originating-IP: [138.32.32.166] From: Laurence KL7UK To: Date: Wed, 4 Aug 2010 06:58:38 -0800 Importance: Normal In-Reply-To: <5A5E700F08A44F948387B7FD7FA8DF44@JimPC> References: ,<359364.83864.qm@web86701.mail.ird.yahoo.com> <002a01cb32f8$bcf915f0$4001a8c0@lark>,<5A5E700F08A44F948387B7FD7FA8DF44@JimPC> MIME-Version: 1.0 X-OriginalArrivalTime: 04 Aug 2010 14:58:39.0020 (UTC) FILETIME=[857BC6C0:01CB33E5] X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,HTML_10_20=0.945,HTML_MESSAGE=0.001 Content-Type: multipart/alternative; boundary="_bc59be21-e7f3-47a6-94ab-17270eba8fd2_" Subject: RE: LF: Noise R75 - rs232 from smpsu - X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=FORGED_HOTMAIL_RCVD, 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-sid: 3039ac1d411f4c5980832325 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --_bc59be21-e7f3-47a6-94ab-17270eba8fd2_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks for the input - Im going to build out a G3YXM version with addition= al input filtering and use a 3 wire version and decouple the output, perha= ps with a switch on the "earth" side for plug and play. =20 What I did find out in Alaska were that not all Earths are equal - here I= mean noise wise. Their are a protective couple of 8ft Earth rods back to= the "mains" switch box where the incomer (2 phase and Neutral) terminated= on the other side of the property -=20 =20 I guess within 15ft of one of those I have a segregated " RF " 8ft rod and= thick copper cable coming back to the shack (long run about 80ft) - this= is primarily for the LF/MF vertical and part of some other 25 radials and= rods that litter the garden - however if I attach this closest radial to= the other radials its induces a fair bit of conducted noise from the powe= r lines - removing the rf rod and leaving the radial removes the noise -= so Im guessing some noise currents running around the 'AC' nearest rods.= =20 =20 I still use it for tx purposes as it along reduces the resistance to 85 oh= m (just this radial) compared with a similar radial on the other side of= the property which gives 110 ohms. At present I keep the RF and power ear= ths segregated as more noise in induced if connected - =20 It does vary from each qth and building earthing and how the supplies are= grounded and Ill play more when I get back to Alaska. As ever I add or ta= ke radials off and on and some add and some subject given their location= and electrical RF Z. Using the AIM 4170 some of them just dont make sense= , but hey RF is a strange bed partner. =20 Laurence KL7 UK =20 > From: james.moritz@btopenworld.com > To: rsgb_lf_group@blacksheep.org > Date: Wed, 4 Aug 2010 10:21:40 +0100 > Subject: Re: LF: Noise R75 - rs232 from smpsu - >=20 > Dear Laurence, LF Group, >=20 > ----- Original Message -----=20 > From: "Alan Melia" > To: > Sent: Tuesday, August 03, 2010 11:35 AM > Subject: Re: LF: Noise R75 - rs232 from smpsu - >=20 >=20 > > Hi Laurence I have found some problems with the "two wire" versions wh= ere > > the powered instrument has no proper ground connection....VLF receiver= s=20 > > etc. > > But often this can be cured by grounding one side of the low-voltage= =20 > > output. >=20 > My experience would agree with Alan - several times with laptops, and al= so a=20 > "compact" desktop with external PSU, making a direct connection between= the=20 > mains ground and the chassis of the computer has made a substantial nois= e=20 > reduction. It seems to be fairly common that there is no ground continui= ty=20 > between input and output of PSU. With no ground connection to the output= =20 > side of the PSU, any common-mode noise due to the PSU has to find its wa= y to=20 > earth via the RF connections usually, and can get into the signal path= in=20 > the process. Winding as many turns as possible of the DC output lead rou= nd a=20 > large split ferrite core can also be helpful in reducing the noise curre= nt.=20 > I find >10 turns are needed to make a useful difference. >=20 > Cheers, Jim Moritz > 73 de M0BMU=20 >=20 >=20 =3D --_bc59be21-e7f3-47a6-94ab-17270eba8fd2_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks for the input - Im going to build out a G3YXM version with addition= al input filtering and use a 3 wire version and decouple the output, perha= ps with a switch on the "earth" side for plug and play.
 
What I did find out in Alaska were that not all Earths are equal - here I= mean noise wise. Their are a protective couple of 8ft Earth rods bac= k to the "mains" switch box where the incomer (2 phase and Neutral)= terminated  on the other side of the property -
 
I guess within 15ft of one of those I have a segregated " RF " 8ft ro= d and thick copper cable coming back to the shack (long run about 80ft) -&= nbsp;this is primarily for the LF/MF vertical and part of some= other 25 radials and rods that litter the garden - however if I attach th= is closest radial to the other radials its induces a fair bit of conducted= noise from the power lines - removing the rf rod and leaving the radial= removes the noise - so Im guessing some noise currents running aroun= d the 'AC' nearest rods.
 
I still use it for tx purposes as it along reduces the resistance to 85 oh= m (just this radial) compared with a similar radial on the other side= of the property which gives 110 ohms. At present I keep the RF and= power earths segregated as more noise in induced  if connected = -
 
It does vary from each qth and building earthing and how the supplies= are grounded and Ill play more when I get back to Alaska. As ever I add= or take radials off and on and some add and some subject given their= location and electrical RF Z. Using the AIM 4170 some of them just dont= make sense, but hey RF is a strange bed partner.
 
Laurence KL7 UK
 
> From: james.moritz@btopenworld.com
> To: rsgb_lf_group@blackshe= ep.org
> Date: Wed, 4 Aug 2010 10:21:40 +0100
> Subject: Re:= LF: Noise R75 - rs232 from smpsu -
>
> Dear Laurence, LF Gro= up,
>
> ----- Original Message -----
> From: "Alan Mel= ia" <alan.melia@btinternet.com>
> To: <rsgb_lf_group@blacks= heep.org>
> Sent: Tuesday, August 03, 2010 11:35 AM
> Subje= ct: Re: LF: Noise R75 - rs232 from smpsu -
>
>
> >= Hi Laurence I have found some problems with the "two wire" versions where=
> > the powered instrument has no proper ground connection....VL= F receivers
> > etc.
> > But often this can be cured by= grounding one side of the low-voltage
> > output.
>
&= gt; My experience would agree with Alan - several times with laptops, and= also a
> "compact" desktop with external PSU, making a direct conn= ection between the
> mains ground and the chassis of the computer= has made a substantial noise
> reduction. It seems to be fairly co= mmon that there is no ground continuity
> between input and output= of PSU. With no ground connection to the output
> side of the PSU,= any common-mode noise due to the PSU has to find its way to
> eart= h via the RF connections usually, and can get into the signal path in
= > the process. Winding as many turns as possible of the DC output lead= round a
> large split ferrite core can also be helpful in reducing= the noise current.
> I find >10 turns are needed to make a usef= ul difference.
>
> Cheers, Jim Moritz
> 73 de M0BMU >
>
=3D --_bc59be21-e7f3-47a6-94ab-17270eba8fd2_--