Topband: 160m noise

[Bill Tippett <btippett@alum.mit.edu>]

Ni6T wrote:
>I am also hearing that many new computer systems have power supplies in
which the line filter component locations on the board are jumpered and that
lower-rated, cheaper parts--such as lower-current rectifiers-- are being
substituted for beefier parts. These computers are both radiating noise and
failing at a high rate. Gee, what a surprise!

        I recently had first-hand experience with this.  When TX9 started 
up on
Topband on October 16, I had an S8 birdie exactly on his frequency 1826.5.  I
don't have very many close neighbors, but do have one about 1000' away to the
Northwest.  I walked around with my Sony 2010 and was able to faintly hear the
noise as I got close to my neighbor's house.  I left a message on their phone
and later the owner gave permission to walk around the house even though 
nobody
was at home that day.  Sure enough, I found the noise was strongest from the
center of their house.  I called back and they said it would be OK to come back
and locate the noise source when someone was home, but they were going to be
away several days.

        Fortunately the next day, when TX9 had a very good signal, the birdie
had drifted to 1824.0, and I was able to work him with no problem.  Had that
birdie not drifted, I would have been completely unable to copy him on 1826.5.

        To make a long story short, the problem was a switching power 
supply in
a new white box computer they had purchased locally.  Rather than dig into it
myself, I simply took it back to the dealer along with my Sony 2010 and
demonstrated the problem.  While I waited, they swapped power supplies and
the problem was gone.  This was all done under warranty since the computer
was brand new.

        Unfortunately I have several other much weaker birdies I have not 
been
able to locate.  The farther they are away, the weaker they are and also much
harder to locate because of the distance to be covered to find them.  I
believe this is becoming a major problem at my location and there is really
not much I can do about it except identify each source myself and then fix 
it.
It's a shame that the FCC is allowing Part 15 devices like these switching
power supplies to be put on the market.

        I should go back to the computer dealer, get the power supply's model
number and manufacturer, and file a complaint with the FCC to send a message
to the manufacturer.  At least Riley Hollingsworth seems to be favorably
inclined to take action on power line interference and electric fencers.

                                                73,  Bill W4ZV
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband