[RFI] Noise to identify

[Mike Martin]

Good advice Don

⁣Be safe,
Mike

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On Jun 7, 2021, 6:56 AM, at 6:56 AM, Don Kirk <wd8dsb at gmail.com> wrote:
>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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