PSN-L Email List Message

Subject: Re: Electronic noise
From: "GPayton" gpayton@.............
Date: Fri, 14 May 2010 12:10:09 -0500


Good information and suggestions.  However, I don't believe that Jon 
mentioned the SOURCE of his interference or the DISTANCE of his needed run. 
Both are important factors to consider.
Regards,
Jerry

  ----- Original Message ----- 
  From: Geoffrey
  To: psn-l@..............
  Sent: Friday, May 14, 2010 12:02 PM
  Subject: Re: Electronic noise


  At the local hardware store ACE BEST or whatever
  I found a signal cable suitable for underground buriel
  which has some kind of grease impregnated beween the shield
  and the cable jacket to keep moisure out.
  I installed a 40 foot run of it several years ago
  and it still seems good. The shield is heavy copper foil
  which makes the cable not as flexable as it might be with
  a braided shield. You just need to shield the jacket from sunlight
  everywhere it might be above ground.

  Also you should avoid what is called ground loops
  which can indice unwanted noise inside the cable
  this can be avoided by choosing your gound
  and making sure the shield is broken at one side of the connection
  or another to eliminate a DC path. I will typically
  break the shield on the side opposite of the
  side chosen as the primary ground.

  DC/LOW FREQUENCIES will travel deep within a conductor.
  But like over 1 MHZ the current exhibits a skin effect
  and only travels like within the first 1/8 inch of the surface
  with that skin getting smaller/thinner as the frequency increases.

  I shoiuld imagine the impedance is also related to this skin effect.

  It seems to play a role in antenna design visible as gamma matching.

  Coaxial cable would be quite suitable for low frequencies
  if 100% shielded and have a proper BALUNS to keep
  RF out of the inside of the cable.
  A BALUNS may be as simple as a series of
  FERRITE beads at  the open ends of the shield.
  The broader the frequency block the more
  beads you need and they are not cheap.
  They come in sizes for one wire or a whole 1/4 inch cable
  as a split bead. I have seen them at Radsio Shack
  in the past.
  You want to make sure what flows on the outside of a coax
  does not leak into the inside. And, Vice Versa.


  ----- Original Message ----- 
  From: "GPayton" 
  To: 
  Sent: Wednesday, May 12, 2010 5:16 PM
  Subject: Re: Electronic noise


  > Jon, in the past I have observed that RCA type (audio) cable may not 
have
  > complete shielding; some ever have had a small thread of wires and 
called it
  > shielded.
  >
  > You might try coaxial cable.
  >
  > Regards,
  > Jerry
  >
  >  ----- Original Message ----- 
  >  From: Jón Frímann
  >  To: PSN-Postlist
  >  Sent: Wednesday, May 12, 2010 7:09 PM
  >  Subject: Electronic noise
  >
  >
  >  Hi all,
  >
  >  I did replace my cable the other day from Cat-5 shielded cable to a RCA
  >  cable that is also shielded. But with the Cat-5 cable I did not get
  >  electronic noise. But with the RCA cable I do. I rather do not want to
  >  switch back to the Cat-5 cable, as it is harder to manage.
  >
  >  What might be the reason why I am seeing electronic noise on the RCA
  >  cable ?
  >
  >  Regards,
  >  -- 
  >  Jón Frímann Jónsson
  >
  >  __________________________________________________________
  >
  >  Public Seismic Network Mailing List (PSN-L)
  >
  >  To leave this list email PSN-L-REQUEST@.............. with
  >  the body of the message (first line only): unsubscribe
  >  See http://www.seismicnet.com/maillist.html for more information.
  >

  __________________________________________________________

  Public Seismic Network Mailing List (PSN-L)

  To leave this list email PSN-L-REQUEST@.............. with
  the body of the message (first line only): unsubscribe
  See http://www.seismicnet.com/maillist.html for more information.







Good information and suggestions.  However, = I don't=20 believe that Jon mentioned the SOURCE of his interference or the = DISTANCE of his=20 needed run.  Both are important factors to consider.
Regards,
Jerry
 
----- Original Message -----
From:=20 Geoffrey=20
Sent: Friday, May 14, 2010 = 12:02 PM
Subject: Re: Electronic = noise

At the local hardware store ACE BEST or whatever
I = found a=20 signal cable suitable for underground buriel
which has some kind of = grease=20 impregnated beween the shield
and the cable jacket to keep moisure=20 out.
I installed a 40 foot run of it several years ago
and it = still=20 seems good. The shield is heavy copper foil
which makes the cable = not as=20 flexable as it might be with
a braided shield. You just need to = shield the=20 jacket from sunlight
everywhere it might be above = ground.

Also you=20 should avoid what is called ground loops
which can indice unwanted = noise=20 inside the cable
this can be avoided by choosing your gound
and = making=20 sure the shield is broken at one side of the connection
or another = to=20 eliminate a DC path. I will typically
break the shield on the side = opposite=20 of the
side chosen as the primary ground.

DC/LOW FREQUENCIES = will=20 travel deep within a conductor.
But like over 1 MHZ the current = exhibits a=20 skin effect
and only travels like within the first 1/8 inch of the=20 surface
with that skin getting smaller/thinner as the frequency=20 increases.

I shoiuld imagine the impedance is also related to = this skin=20 effect.

It seems to play a role in antenna design visible as = gamma=20 matching.

Coaxial cable would be quite suitable for low=20 frequencies
if 100% shielded and have a proper BALUNS to keep
RF = out of=20 the inside of the cable.
A BALUNS may be as simple as a series=20 of
FERRITE beads at  the open ends of the shield.
The = broader the=20 frequency block the more
beads you need and they are not = cheap.
They=20 come in sizes for one wire or a whole 1/4 inch cable
as a split = bead. I=20 have seen them at Radsio Shack
in the past.
You want to make = sure what=20 flows on the outside of a coax
does not leak into the inside. And, = Vice=20 Versa.


----- Original Message -----
From: "GPayton" = <gpayton@.............>
To= :=20 <psn-l@..............>
Sent= :=20 Wednesday, May 12, 2010 5:16 PM
Subject: Re: Electronic=20 noise


> Jon, in the past I have observed that RCA type = (audio)=20 cable may not have
> complete shielding; some ever have had a = small=20 thread of wires and called it
> shielded.
>
> You = might try=20 coaxial cable.
>
> Regards,
> = Jerry
>
> =20 ----- Original Message -----
>  From: J=F3n = Fr=EDmann
> =20 To: PSN-Postlist
>  Sent: Wednesday, May 12, 2010 7:09=20 PM
>  Subject: Electronic = noise
>
>
>  Hi=20 all,
>
>  I did replace my cable the other day from = Cat-5=20 shielded cable to a RCA
>  cable that is also shielded. But = with=20 the Cat-5 cable I did not get
>  electronic noise. But with = the RCA=20 cable I do. I rather do not want to
>  switch back to the = Cat-5=20 cable, as it is harder to manage.
>
>  What might be = the=20 reason why I am seeing electronic noise on the RCA
>  cable = ?
>
>  Regards,
>  --
>  J=F3n = Fr=EDmann=20 J=F3nsson
>
> =20 = __________________________________________________________
>
>= ; =20 Public Seismic Network Mailing List (PSN-L)
>
>  To = leave=20 this list email PSN-L-REQUEST@............... =20 with
>  the body of the message (first line only):=20 unsubscribe
>  See http://www.seismicnet.co= m/maillist.html=20 for more information.
>=20 =

__________________________________________________________
Public=20 Seismic Network Mailing List (PSN-L)

To leave this list email = PSN-L-REQUEST@............... =20 with
the body of the message (first line only): unsubscribe
See = http://www.seismicnet.co= m/maillist.html=20 for more information.

[ Top ] [ Back ] [ Home Page ]