[amsat-bb] Re: RFI identification

Joe nss at mwt.net
Thu Jan 24 07:18:20 PST 2008

 From Joe WB9SBD

if i'm listening to a dead quiet band,  and i turn on a computer,  any 
computer,  I hear the difference.  weak signals WILL  be masked.

My local club was operating  CQ world wide  DX contest just last year.  
State of the art systems all  around.  Great antennas  multi monobanders 
all  at 100 feet plus.

They had the station networked with computers, for logging  duping etc.  
when i got there do do my shift in the contest, they all  complained how 
dead the bands were.  i got on, and in a half hour agreed that we were 
not hearing hardly anything.  BUT

as soon as we shut down the puters,  we sat on one freq and started 
running a pile up of JAPAN Stations,  qso rate was in excess of 120 per 
hour minimum.  we were paper logging then,

then someone turned the puters back on, for logging and duping and the 
qso rate immediately dropped to less than 30 per hour we were just NOT 
hearing them anymore,,  again shut it down and the qso rate doubled if 
not tripled.

now everyone in our club is a believer and never runs a computer when 
operating on any band.

Wayne Estes wrote:

>Joe (no callsign given) wrote:
>Computers are also extremely noisy!  When operating HF I never use a
>computer, every one I have ever had or used, adds at least 10 DB to the
>noise floor.
>Wayne replies:
>How close are your HF antennas to you computers?  I don't notice an 
>increase in the HF noise level from the computers in my house, but my HF 
>vertical and HF dipole feedpoint are both 60 feet from the house (and 
>even further from neighbor's houses).  At the closest point the dipole's 
>wire is less than 30 feet from two computers in the house.
>Do you use CRT monitors with your computers?  I found that CRT monitors 
>generate much more RF noise than the average home computer.  LCD 
>monitors produce far less RFI.  Weak-signal ham operators should NEVER 
>use CRT monitors.
>Wayne Estes W9AE
>Oakland, Oregon, USA, CN83ik
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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