RFI
[Top] [All Lists]

[RFI] Nutone Intercom RFI

To: <rfi@contesting.com>
Subject: [RFI] Nutone Intercom RFI
From: tim-taylor@home.com (Tim Taylor)
Date: Fri, 7 Dec 2001 19:11:43 -0500
This is a multi-part message in MIME format.

------=_NextPart_000_008A_01C17F53.02118400
Content-Type: text/plain;
        charset="iso-8859-1"
Content-Transfer-Encoding: 7bit


I need some help.  I've been trying to solve an interference problem with my
neighbors Nutone Intercom for some time now.  He has an extensive system
with 19 speakers.  At first, I thought the RF was coming in through the
speaker leads.  I investigated what it might take to eliminate that.  By
chance, during a test, I removed the doorbell module, and the RFI stopped.
The doorbell module connects to the doorbell with a two conductor cable.
One side is ground and the other side is the input to the module.  I have
tried the following:

.01 uF cap across doorbell - no effect

.01 uF cap across input terminals to doorbell module - no effect

put 10 ferrite beads on each lead at doorbell module - some reduction, but
still audible



I also noticed that both the ground and input leads must be disconnected to
eliminate the RFI.  If either wire is left connected, the RFI is present.  I
tried a clip lead between the doorbell module ground wire and the intercom
chassis - no effect.



I have hope in that it appears that the RF is not coming in through the
speakers.  I have isolated it down to two wire.  This should be simple.



Can anybody help?



Thanks,

Tim K8XS


------=_NextPart_000_008A_01C17F53.02118400
Content-Type: text/html;
        charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
<META content=3D"MSHTML 5.50.4616.200" name=3DGENERATOR></HEAD>
<BODY>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV class=3DSection1>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>I need some =
help.&nbsp; I've=20
been trying to solve an interference problem with my neighbors Nutone =
Intercom=20
for some time now.&nbsp; He has an extensive system with 19 =
speakers.&nbsp; At=20
first, I thought the RF was coming in through the speaker leads.&nbsp; I =

investigated what it might take to eliminate that.&nbsp; By chance, =
during a=20
test, I removed the doorbell module, and the RFI stopped.&nbsp; The =
doorbell=20
module connects to the doorbell with a two conductor cable.&nbsp; One =
side is=20
ground and the other side is the input to the module.&nbsp; I have tried =
the=20
following:</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>.01 uF cap =
across doorbell -=20
no effect</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>.01 uF cap =
across input=20
terminals to doorbell module - no effect</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>put 10 ferrite =
beads on each=20
lead at doorbell module - some reduction, but still=20
audible</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000=20
size=3D2></FONT></SPAN></SPAN>&nbsp;</P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>I also noticed =
that both the=20
ground and input leads must be disconnected to eliminate the RFI.&nbsp; =
If=20
either wire is left connected, the RFI is present.&nbsp; I tried a clip =
lead=20
between the doorbell module ground wire and the intercom chassis - no=20
effect.</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000=20
size=3D2></FONT></SPAN></SPAN>&nbsp;</P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>I have hope in =
that it=20
appears that the RF is not coming in through the speakers.&nbsp; I have =
isolated=20
it down to two wire.&nbsp; This should be =
simple.</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000=20
size=3D2></FONT></SPAN></SPAN>&nbsp;</P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>Can anybody=20
help?</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000=20
size=3D2></FONT></SPAN></SPAN>&nbsp;</P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000=20
size=3D2>Thanks,</FONT></SPAN></SPAN></P>
<P style=3D"MARGIN: 6pt 0in"><SPAN=20
style=3D"COLOR: blue; FONT-FAMILY: Arial; mso-bidi-font-size: =
10.0pt"><SPAN=20
class=3D370460100-08122001><FONT color=3D#000000 size=3D2>Tim=20
K8XS</FONT></SPAN></SPAN></P></DIV></BODY></HTML>

------=_NextPart_000_008A_01C17F53.02118400--


<Prev in Thread] Current Thread [Next in Thread>