[Yaesu] Noise.

[KD7JYK DM09]

I bought a new four-input 19" high-res LCD monitor for my computer for $10!

At the time, the co-ax to my HF antenna was damaged, so, no radio, no noise.

I fix the co-ax, guess what??  HF is wiped out!

A friend was visiting for a couple of weeks and she had an interest in weak
signal and long time integration.  I determined most of the noise was from
the monitor by turning it on and off, but hard to analyse signals with no
view, so I had a great idea.  I put the 18" whip from my Heathkit Field
Strength meter into a barrel connector on the end of a 10' pice of co-ax on
the HF rig and started sniffing around the shack.

Most all the noise came from the computer and monitor, so I started playing
around.  First, I hung the "antenna" down the back of the desk, into the
rats nest of cables behind the computer, then, I started moving and changing
cables.  I played with shielded cables, cable with ferrites molded on, even
a combination of the two.  Shielded cables are far and few betwen, so I
couldn't eliminate all the noise that way and the cables with the ferrites
could remove most noise from a device end of a cable, but still excessive
noise from the computer end.

I then experimented with putting loops of cable at the device and the
computer ends.

I used two cables for length, then made four to six loops near EACH end and
secured them with wire ties.

Now, even with the antenna amid the cables and using various spectrum
analysis and signal detection software, it is difficult to see\hear any
noise at all.  When I connect to the outside antenna, 125 feet away, there
is absolutely NO noise in my receivers from my equipment.

Here's the GREAT part!

These simple coils\wraps\loops, work BOTH WAYS!

Over the years, I have used the same technique to eliminate problems from
stereos, computers, telephones, alarms (house, auto, building), answering
machines, automated sprinklers, you name it.  There has NOT been a single
item I've done this with that I can't cure all the noise or RFI, even
running 225W within thirty feet!

I HAVE (!!!!) had problems over the years using most RFI "eliminating"
devices sold on the market, outside of helical band-pass filters.  I've even
used simple loops in power supply, data and audio cables in RF sewers such
as major mountain top communications sites.  A local APRS digipeater had
problems with power spikes, RFI, corrupt data, locking modem and full scale
out of band noise in the receiver.  ALL the problems were RFI on the power
and data cable.  Four to five loops in each cable and a shorter ground wire
solved all the probems, the station has been running without failures since
2001.

For the fellow with the RFI problem to his alarm, I suggest putting a few
loops in his phone, power and control wires at the devices.  If possible,
pull the control pad from the wall, put a few turns in the extra wire behind
it, if possible, a few turns where the wires enter the control box, the
phone line and power lines, everthing.  Ground your control box if it isn't
already.

Kurt