[RFI] Noise to identify

[Don Kirk]

Hi Hugo,

Quickly looking at your waterfall display on 160 and 80 meters, it looks
like a repeating pattern at a frequency of approximately 6 KHz, and also a
comb pattern at a frequency of approximately 640 Hz.  These patterns are
not easily observable on your 40 meter display.  6 KHz is a very common
carrier frequency on variable speed drives, but there are numerous other
devices that could be generating repeating 6 KHz patterns, etc.

While I do look at waterfall displays to help me understand what the signal
looks like that I'm trying to locate, I normally don't waste time guessing
what the device might be that's generating the RFI.  What's important is
identifying the property that's generating the RFI, and then you can
investigate more with the property owner exactly what device is generating
the RFI.  Even if I told you the exact model number of a device that's
generating the RFI, it does you no good until you locate the property it's
located on, and you have to do this using radio direction finding gear
(your HF radio, a simple directional antenna that's easy to build , and
possibly a preamp and attenuators or RF gain control).

Sounds like you already did the first step and determined the RFI is not
being generated within your house which is always the first step.

 I would be interested in knowing if this RFI is present 24 hours a day, or
if there are only certain hours of the day it's on and how often the 6 KHz
pattern disappears as I noticed it would go off for brief periods of time
in your video, etc.  This would help me understand when I should go
direction finding and how not to get fooled by the 6 KHz pattern turning on
and off while out hunting.  I would also be interested in knowing if you
see this same pattern on additional bands as this would help me decide what
bands would be best for my radio direction finding activities (what antenna
would be good for direction finding and I might not even need a preamp if I
can hear it on one of the higher bands like 20 or 15 meters where the size
of the  portable direction finding antenna does not need to be as large and
still not have such negative gain as a portable antenna for use on 160 or
80 meters as an example).

Just my opinion based on tracking down many RFI cases for myself and
others.  Tracking down a signal with a definite signature like what you are
seeing on 160 and 80 meters is usually one of the easiest cases to track
down (normally less than an hour or two) as long as you have some basic
radio direction finding equipment.

Again the key is to locate the property where the RFI is coming from, and
then you can worry about finding out exactly what device is generating the
RFI.

73,
Don (wd8dsb)

On Sun, Jun 6, 2021 at 11:37 PM Hugo Loranger <ve2_ugo at hotmail.com> wrote:

> Hi,
>
> I have already closed the braker and no change. I have stopped all the
> UPS. I used my KX3 on battery power. No change.
> Here are 3 other videos including one with the waterfall that Jim was
> asking for.
> The last one shows the waterfall via Nap3 on 3 bands(80m, 160m and 40m am).
>
> https://youtu.be/Syn973SUDSY  - Part 2
>
> https://youtu.be/kV89pinFfZc  - Part 3
>
> https://youtu.be/uKfoQV8NzpU  - Part 4 with waterfall
>
> I don't know if this helps more but it looks a lot like an electrical
> problem that covers all the bands ...
>
> Indeed it shows that there is repetition which was not well audible ...
>
> The shack is just above the electrical box in the house. It is a house but
> the other houses are very close together.
> The power line that supplies the house is 52 feet away. The horizontal
> antenna is therefore not very far ...
> On the other hand, I have 2 lines within 2 km of 740kv ...
>
>
> Thanks!
>
>
> Hugo
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