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Date: Sat, 21 Aug 2010 05:41:10 -0700 (PDT)
From: Daniele Tincani <danieletincani@yahoo.com>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <4C6FC2BD.1030100@iup.uni-heidelberg.de>
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Subject: Re: LF: OT - RF noise from PC display: LCD vs CRT
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Hello Stefan,
Thank you for your reply.Yes I think you are right.=A0So probably I will=
 let time=20
take the decision :-) As long as the CRT survives, I will stay with it (at=
 least=20
I know I can switch it off while the received signal is recorded on the ha=
rd=20
disk e.g. at nigth). Then I suppose I will=A0move to an LCD one to save sp=
ace and=20
power.
Cheers
Daniele




________________________________
From: Stefan Sch=E4fer <schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Sat, August 21, 2010 2:12:45 PM
Subject: Re: LF: OT - RF noise from PC display: LCD vs CRT

Hi Daniele,

The older CTR monitor seems to have a "real" switch that yust disconnect=
 the=20
mains from the supply (like it should be!). As you said, there is QRM near=
 the=20
both monitors. The SMPS in the LCD monitor is active all the time, so ther=
e is=20
QRM all the time but it should be just detectable in some 10 cm.

The question is, if and how the noise is (hopefully) decoupled from the ca=
bles=20
going in and out from/to the monitor. This is essential since your RX ante=
nna=20
will not be placed in the near of the monitor, i suppose ;-)=20


For example, i have very good experience with my tiny netbook as a VLF RX=
=20
although it has a LCD display near the internal soundcard and the keyboard=
 as=20
well. So the LCD monitors are not worse in principal. EMC is an issue at=
 all=20
monitors so you have just to check the difference in your case.

73, cu, Stefan

Am 21.08.2010 13:16, schrieb Daniele Tincani:=20
Hi LF, VLF,
>
>currently I have a CRT monitor which of course is a bit cumbersome compar=
ed with=20
>a slim LCD one. On the other hand, I have done a very simple RF noise tes=
t with=20
>an LCD TV/monitor I had in another room and=A0I have found the LCD is=20
>significantly noisier than the CRT. I have simply checked the noise using=
 a=20
>portable radio close to the screen on LF (abt 300KHz) and MF (abt 900KHz)=
.
>The LCD generates RF noise even when powered off (because of an internal=
 power=20
>supply, I suppose), while the CRT doesn't.
>As I plan to use my SDR in LF/MF in the vicinity of the PC (and my poor=
 VLF loop=20
>antenna usually sits only five meters apart), the RF noise from monitor=
 could be=20
>an important factor.
>Did you find similar or different results in your experience?
>
>Best regards
>Daniele
>
>


     =20

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<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></h=
ead><body><div style=3D"font-family:arial, helvetica, sans-serif;font-size=
:10pt"><DIV>Hello Stefan,</DIV>
<DIV>
<DIV>Thank you for your reply.</DIV>Yes I think you are right.&nbsp;So pro=
bably I will let time take the decision :-) As long as the CRT survives,=
 I will stay with it (at least I know I can switch it off while the receiv=
ed signal is recorded on the hard disk e.g. at nigth). Then I suppose I wi=
ll&nbsp;move to an LCD one to save space and power.</DIV>
<DIV>Cheers</DIV>
<DIV>Daniele<BR></DIV>
<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 10pt">=
<BR>
<DIV style=3D"FONT-FAMILY: times new roman, new york, times, serif; FONT-S=
IZE: 12pt"><FONT size=3D2 face=3DTahoma>
<HR SIZE=3D1>
<B><SPAN style=3D"FONT-WEIGHT: bold">From:</SPAN></B> Stefan Sch=E4fer &lt=
;schaefer@iup.uni-heidelberg.de&gt;<BR><B><SPAN style=3D"FONT-WEIGHT: bold=
">To:</SPAN></B> rsgb_lf_group@blacksheep.org<BR><B><SPAN style=3D"FONT-WE=
IGHT: bold">Sent:</SPAN></B> Sat, August 21, 2010 2:12:45 PM<BR><B><SPAN=
 style=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> Re: LF: OT - RF noise fro=
m PC display: LCD vs CRT<BR></FONT><BR>Hi Daniele,<BR><BR>The older CTR mo=
nitor seems to have a "real" switch that yust disconnect the mains from th=
e supply (like it should be!). As you said, there is QRM near the both mon=
itors. The SMPS in the LCD monitor is active all the time, so there is QRM=
 all the time but it should be just detectable in some 10 cm.<BR><BR>The=
 question is, if and how the noise is (hopefully) decoupled from the cable=
s going in and out from/to the monitor. This is essential since your RX an=
tenna will not be placed in the near of the monitor, i suppose ;-) <BR><BR=
>For example, i
 have very good experience with my tiny netbook as a VLF RX although it ha=
s a LCD display near the internal soundcard and the keyboard as well. So=
 the LCD monitors are not worse in principal. EMC is an issue at all monit=
ors so you have just to check the difference in your case.<BR><BR>73, cu,=
 Stefan<BR><BR>Am 21.08.2010 13:16, schrieb Daniele Tincani:=20
<BLOCKQUOTE type=3D"cite">
<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 10pt">
<DIV>Hi LF, VLF,<BR></DIV>
<DIV>currently I have a CRT monitor which of course is a bit cumbersome co=
mpared with a slim LCD one. On the other hand, I have done a very simple=
 RF noise test with an LCD TV/monitor I had in another room and&nbsp;I hav=
e found the LCD is significantly noisier than the CRT. I have simply check=
ed the noise using a portable radio close to the screen on LF (abt 300KHz)=
 and MF (abt 900KHz).</DIV>
<DIV>The LCD generates RF noise even when powered off (because of an inter=
nal power supply, I suppose), while the CRT doesn't.</DIV>
<DIV>As I plan to use my SDR in LF/MF in the vicinity of the PC (and my po=
or VLF loop antenna usually sits only five meters apart), the RF noise fro=
m monitor could be an important factor.</DIV>
<DIV>Did you find similar or different results in your experience?<BR></DI=
V>
<DIV>Best regards<BR>Daniele<BR></DIV></DIV><BR></BLOCKQUOTE></DIV></DIV><=
/div><br>

      </body></html>

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