[RFI] Sense antenna for ANC-4 power line rfi?

[Dave Cole]

That is an excellent observation...  When you phase cancel two signals, 
in a perfect world, they would be the same, and cancel one hundred 
percent...  Unfortunately the grower two blocks away from my home is 
both a distributed source, and a specular source.

He is spraying me with direct RF, (specular), and with power line 
re-radiated RF, (distributed), if only I could hang my noise antenna on 
his lights-- but then I would have to enter his home, and run coax two 
blocks...

Phase canceling noise devices work very well for what they are designed 
for, but not in all cases...  Which was my initial point.

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 1/13/21 11:14 AM, Mark Schoonover via RFI wrote:
> I'll throw my 0.02USD in as well. I use the MFJ-1026 and I found it to work
> best when my noise antenna was receiving about the same amount of noise as
> my main antenna. My main antenna at the time was a 40M horizontal loop up
> 35', the noise antenna ended up being 50' of wire helically wound on a 10'
> crappie fishing pole. I noticed using the noise antenna gain on the MFJ
> could lead to distortion at the higher settings so I kept it set below 3 on
> the dial - whatever that meant. I made a video using the MFJ :
> https://youtu.be/tTBKULHn8Rw and a comprehensive RFI video :
> https://youtu.be/K_1hBFMzbAs
> 
> 73! Mark KA6WKE
> Youtube: https://www.youtube.com/ka6wke
> Website: https://www.ka6wke.net
> 
> 
> 
> On Wed, Jan 13, 2021 at 10:54 AM myles landstein <myles.landstein at gmail.com>
> wrote:
> 
>> I’ll also throw in,  if you're using the anc4 as designed. I did find it
>> very helpful for getting rid of a few kinds of noise in few specific
>> circumstances , worked great.
>>
>> your millage my vary
>>
>> regards
>> n2ehg
>> myles
>>
>>> On Jan 13, 2021, at 1:20 PM, Cianciolo, Paul, W1VLF <pcianciolo at arrl.org>
>> wrote:
>>>
>>> I call it "quality noise"
>>> You want just your target  noise to invert and cancel.
>>>
>>> Anything else will tend to add "new" noises from the pickup antenna.
>>> See here
>>>
>>> https://youtu.be/spre7Wn0Kqs
>>>
>>>
>>> 73,
>>>
>>> Paul Cianciolo, W1VLF
>>> ARRL EMC Engineer
>>>
>>> ARRL - The national association for Amateur Radio™
>>> 225 Main Street, Newington, CT 06111-1400 USA
>>> Telephone: (860) 594-0392
>>> FAX: (860) 594-0259
>>> Email: w1vlf at arrl.org
>>> World Wide Web: www.arrl.org
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: RFI <rfi-bounces+pcianciolo=arrl.org at contesting.com> On Behalf Of
>> Mike Martin
>>> Sent: Wednesday, January 13, 2021 11:57 AM
>>> To: Dave Cole <dave at nk7z.net>
>>> Cc: rfi at contesting.com
>>> Subject: Re: [RFI] Sense antenna for ANC-4 power line rfi?
>>>
>>> Hey guys consider this, you can look at a noise on two antennas exactly
>> the same but located in different places in your yard and see different
>> noises. That's a fact.
>>> So if you're using a noise cancellation device you can't expect the
>> antenna you're using for that device to see the same noise that you see
>> when the antenna with the symptoms. So you have to make sure that the
>> cancellation device antenna is seeing the same noise that you're picking up
>> in your receivers and causing interference to the one it's signal. once you
>> achieve that then the noise cancellation device will work quite well. but
>> if your noise cancellation device sees a different noise then you're
>> canceling the wrong noise therefore it doesn't work properly. I wish I had
>> more time to explain further but unfortunately I'm out here looking for
>> noise and don't have the time.
>>> Just so you know I also don't have time to proofread my voice to text
>> message so please excuse the mistakes and type of graphical errors. LOL
>>>
>>> ⁣Happy 2021,
>>> Mike
>>>
>>> Get BlueMail for Android ​
>>>
>>> On Jan 13, 2021, 9:15 AM, at 9:15 AM, Dave Cole <dave at nk7z.net> wrote:
>>>> Charles,
>>>>
>>>> You may find that the phase type noise reducers don't work so well on
>>>> power line noise...  It can help-- but mostly it will not be very
>>>> effective for distributed RFI sources.
>>>>
>>>> The source of transmission can be distributed, (not in all cases),
>>>> along several hundred, to several thousand feet of power line.  This
>>>> means that depending on the distance traveled down the power line, the
>>>> distance to your sense antenna, and the distance to your main antenna,
>>>> RFI will arrive at different times, and hence different phase
>>>> relationships to each other, from every point along the power line that
>>>>
>>>> carries the RFI.
>>>>
>>>> Given that the ANC-4 is a phase cancellation device, (it looks at your
>>>> main antenna, and your sense antenna, and tries to phase cancel an  RF
>>>> signal based on phase relationship), this can cause no end of issues.
>>>>
>>>> Now imagine the signals the ANC will see if your RFI is being
>>>> re-radiated along several hundred, or thousand feet of power line.  You
>>>>
>>>> will be able to cancel some, but not a lot of the RFI.
>>>>
>>>> If you are lucky, you will have a specular source, and no re-radiation,
>>>>
>>>> which will allow you to cancel most of the offending signal out...
>>>>
>>>> Your idea is a good one, and might help...  RFI suppression is always
>>>> fun, when it works...  Good luck.  Please do post your results.
>>>>
>>>> 73, and thanks,
>>>> Dave (NK7Z)
>>>> https://www.nk7z.net
>>>> ARRL Volunteer Examiner
>>>> ARRL Technical Specialist, RFI
>>>> ARRL Asst. Director, NW Division, Technical Resources
>>>>
>>>> On 1/12/21 11:07 PM, Charles Plunk wrote:
>>>>> While waiting on my powerline arc to return in force enough to have
>>>>> confidence it will be ongoing when I call TVA in, thought I would
>>>> play
>>>>> with improving the sense antenna on my Timewave ANC-4. The 3 phase
>>>> power
>>>>> runs at the edge of my lot up to the suspect pole. So the noise is
>>>>> radiating up this way and all the more reason its strong on me I
>>>>> suspect. I have a storage building underneath the lines. I am
>>>> thinking
>>>>> about a vertical made for a scanning receiver I came across and
>>>> mounting
>>>>> it up under the lines on that building. I will tack it up there
>>>> somehow
>>>>> and move it around to get a sweet spot maybe. Any better ideas?
>>>>>
>>>>> Thanks,
>>>>> Chuck
>>>>> AF4O
>>>>>
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