Hi Ray, thanks for that link. As an EMC engineer, I assumed “loop antennas”
were designed much like fully shielded (balanced) H-field probes I use in the
near field. I had no idea of the variety of “shielded loop antennas”, so that
link was very educational. Thanks!
Ken
________________
Ken Wyatt
wyattphoto@mac.com
> On Mar 23, 2021, at 1:45 PM, rfi-request@contesting.com wrote:
>
> Send RFI mailing list submissions to
> rfi@contesting.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://lists.contesting.com/mailman/listinfo/rfi
> or, via email, send a message with subject or body 'help' to
> rfi-request@contesting.com
>
> You can reach the person managing the list at
> rfi-owner@contesting.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of RFI digest..."
>
>
> Today's Topics:
>
> 1. Re: RFI Digest, Vol 218, Issue 27 (Ray LaRue)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 23 Mar 2021 19:45:30 +0000
> From: Ray LaRue <w4byg@att.net>
> To: rfi@contesting.com
> Subject: Re: [RFI] RFI Digest, Vol 218, Issue 27
> Message-ID: <cd0ae380-11e0-541f-2994-b6205a152df9@att.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I'm afraid the email below is just repeating an error about how loop
> antennas work. (They say if you hear something repeated enough times it
> is is perceived as truth). But not so. For an excellent paper on how
> loop antennas work see:
>
> https://w8ji.com/magnetic_receiving_loops.htm
>
> Ray, W4BYG
>
>
> On 3/23/2021 19:16, Kenneth Wyatt via RFI wrote:
>> Tom,
>>
>> The usual loop antenna design picks up magnetic fields, which tend to be
>> dominant from SMPS transformers and inductors.
>>
>> Cheers, Ken
>> ________________
>> Ken Wyatt
>> wyattphoto@mac.com
>>
>>
>>
>>
>>
>>> On Mar 23, 2021, at 1:11 PM, rfi-request@contesting.com wrote:
>>>
>>> Send RFI mailing list submissions to
>>> rfi@contesting.com
>>>
>>> To subscribe or unsubscribe via the World Wide Web, visit
>>> http://lists.contesting.com/mailman/listinfo/rfi
>>> or, via email, send a message with subject or body 'help' to
>>> rfi-request@contesting.com
>>>
>>> You can reach the person managing the list at
>>> rfi-owner@contesting.com
>>>
>>> When replying, please edit your Subject line so it is more specific
>>> than "Re: Contents of RFI digest..."
>>>
>>>
>>> Today's Topics:
>>>
>>> 1. Re: New Interference at kk0sd (Tom Thompson)
>>> 2. Re: New Interference at kk0sd (Don Kirk)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Tue, 23 Mar 2021 12:27:45 -0600
>>> From: Tom Thompson <w0ivj@tomthompson.com>
>>> To: Mike Martin <mike@rfiservices.com>, Gary
>>> <gary_mayfield@hotmail.com>
>>> Cc: Rfi List <rfi@contesting.com>
>>> Subject: Re: [RFI] New Interference at kk0sd
>>> Message-ID: <fff7cac5-fe47-3b8a-20f1-349436e51149@tomthompson.com>
>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>>
>>> See:? http://tomthompson.com/radio/ReceivingLoop/loop.html? for a tuned
>>> loop.? You can build one in a couple of hours from your junk box.? This
>>> type of loop does not work well for power line noise ( a vhf yagi is
>>> better for that), but it does work well for switch mode RFI.? Since most
>>> of these noise sources are vertically? polarized, look through the loop
>>> for the null and along the edge for the peak. When close to the source,
>>> the polarization may switch.
>>>
>>> 73,?? Tom?? W0IVJ
>>>
>>> On 3/23/2021 6:32 AM, Mike Martin wrote:
>>>> Remember in his shack he has a very good radio and a very good antenna
>>>> which together increased sensitivity and allow him to hear much further
>>>> away. when he goes outside with a portable and a smaller antenna he
>>>> doesn't have the sensitivity he had inside there for he may have to travel
>>>> a lot further before he's able to receive it.
>>>>
>>>> ?Be safe,
>>>> Mike
>>>>
>>>> Get BlueMail for Android ?
>>>>
>>>> On Mar 22, 2021, 11:37 PM, at 11:37 PM, Gary <gary_mayfield@hotmail.com>
>>>> wrote:
>>>>> Kim,
>>>>>
>>>>> I hear it on the portable when connected to the vertical antenna, but
>>>>> will undertake an antenna substitution experiment this weekend.
>>>>>
>>>>> Keep the suggestions coming!
>>>>>
>>>>> 73 and Thanks,
>>>>> Gary "Joe", kk0sd
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: RFI <rfi-bounces+gary_mayfield=hotmail.com@contesting.com> On
>>>>> Behalf Of Kim Elmore
>>>>> Sent: Monday, March 22, 2021 4:44 PM
>>>>> To: Don Kirk <wd8dsb@gmail.com>
>>>>> Cc: Rfi List <rfi@contesting.com>
>>>>> Subject: Re: [RFI] New Interference at kk0sd
>>>>>
>>>>> That?s a great idea, too! I once ran into an interference problem that
>>>>> was inherent to the antenna, but only under certain conditions. It
>>>>> didn?t sound like Gary?s but I pulled a lot of hair out fixing that
>>>>> one. I?m simply suspicious that he hears NOTHING with his portable rx
>>>>> so I?m after eliminating anything inherent to his station. Standing by
>>>>> his vertical with his portable rx is a great idea.
>>>>>
>>>>> 73,
>>>>>
>>>>> Kim N5OP
>>>>>
>>>>> "People that make music together cannot be enemies, at least as long as
>>>>> the music lasts." -- Paul Hindemith
>>>>>
>>>>>> On Mar 22, 2021, at 2:24 PM, Don Kirk <wd8dsb@gmail.com> wrote:
>>>>>>
>>>>>> ?
>>>>>> Hi Dave,
>>>>>>
>>>>>> I still recommend tuned and untuned loops to folks on an almost daily
>>>>> basis but they definitely don?t shed as much light on the situation as
>>>>> a unidirectional antenna does. It would be nice to see what your
>>>>> shielded untuned loop design is.
>>>>>> The beauty of the portable flag which is unidirectional is that you
>>>>> typically can walk right to the source (no guessing which direction the
>>>>> signal is coming from). I still pack 7 antennas when I go on a RFI
>>>>> case, and this includes 3 tuned HF loops, but I have found that I
>>>>> typically don?t use bidirectional loops anymore (unless I?m trying to
>>>>> be more stealth) as the portable flag saves me an enormous amount of
>>>>> time. Also in heavily congested areas (like downtown Indianapolis)
>>>>> having the unidirectional HF antenna is priceless as it unmasks noise
>>>>> that?s mixing from other sources that are in the opposite direction,
>>>>> etc. Yesterday I worked on a case (more of a country setting) where I
>>>>> had 2 different bad poles that were only 0.14 miles apart plus a 3rd
>>>>> RFI source generating spikes every 1 KHz within the same area and
>>>>> having the unidirectional HF antenna helped me locate all 3 sources in
>>>>> a matter of minutes (way under an hour).
>>>>>> You can never have enough antennas in your direction finding bag of
>>>>> tricks but after using a unidirectional HF antenna like the portable
>>>>> flag for direction finding I can?t imagine not using one. It typically
>>>>> takes me seconds to tell which direction the signal is without the need
>>>>> of triangulation, etc. Traditional triangulation has almost become a
>>>>> thing of the past for me.
>>>>>> I also have been helping a ham that has the MFJ unit (the one with a
>>>>> beam and the one with a dipole) and while it has helped him, it has an
>>>>> odd characteristic that makes the meter jump which causes confusion to
>>>>> him and after looking at the schematic I question how they implemented
>>>>> AGC in those units. I?m starting to think AGC in a radio direction
>>>>> finding system is typically not desirable. Manual attenuation is
>>>>> priceless but I don?t want anything changing gain automatically.
>>>>>> Just my opinion from tracking down RFI on an almost continuous basis
>>>>> in addition to my day job.
>>>>>> Please share details on your shielded untuned loop and thanks.
>>>>>>
>>>>>> 73,
>>>>>> Don wd8dsb
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On Mon, Mar 22, 2021 at 1:22 PM David Eckhardt
>>>>> <davearea51a@gmail.com> wrote:
>>>>>>> We recently found a faulty lightning 'arrestor' on a pole by using
>>>>>>> both the MFJ device and a small shielded loop (easy home brew
>>>>>>> project) into a battery-powered receiver. We had two of us in the
>>>>>>> field. One wielded the MFJ and I had the small (0.5-meter) shielded
>>>>>>> loop fed into the Yaesu VR-500 on 1.830 MHz (160-meters). We both
>>>>>>> independently found the same source / pole in the field. The null
>>>>> on
>>>>>>> the shielded loop is extremely sharp and this piece of hardware
>>>>>>> should be in the bag of tricks of anyone sleuthing RFI. It is a
>>>>>>> powerful tool when coupled to a battery-powered receiver with its
>>>>>>> extremely sharp null (perpendicular to the plane of the loop). One
>>>>> doesn't need something as large as the 'Flag" that was recently
>>>>> published
>>>>>>> in QST and referred to in a previous post in this thread. Another
>>>>> plus
>>>>>>> for the shielded loop is that in the field, one can tune the
>>>>> receiver
>>>>>>> to the worst-case frequency of the RFI as I did in the related
>>>>> story, above.
>>>>>>> The shielded loop is untuned. The MFJ relies only on VHF noise.
>>>>> In some
>>>>>>> cases, an ultrasonic microphone at the focus of a small parabolic or
>>>>>>> spherical reflector is good at finding coronal discharges as well as
>>>>>>> active arcs and discharges. MFJ also makes that at a reasonable
>>>>> price.
>>>>>>> Our power provider was out the next day to fix the problem. We even
>>>>>>> gave them the pole number which is a great help to any power
>>>>> provider.
>>>>>>> Dave - W?LEV
>>>>>>>
>>>>>>> On Mon, Mar 22, 2021 at 2:28 AM Kim Elmore
>>>>> <cw_de_n5op@sbcglobal.net> wrote:
>>>>>>>> It's odd that you can't hear it on your portable rx. That made me
>>>>>>>> curious: What if this is something internal to your '847? Have you
>>>>>>>> tried pulling your '847 and listening on a different receiver
>>>>> using
>>>>>>>> the same antenna? If you have, do you still hear the noise? It's a
>>>>> long shot, but...
>>>>>>>> Kim N5OP
>>>>>>>>
>>>>>>>> On 3/21/2021 7:28 PM, Gary wrote:
>>>>>>>>> Mike,
>>>>>>>>>
>>>>>>>>> Thanks for the info. I understand locating the
>>>>>>>>> noise is
>>>>>>>> more important than identifying the noise. I am just try to play
>>>>>>>> all the angles as I was hoping to work the WPX contest nest
>>>>>>>> weekend. I have been walking the neighborhood a good chunk of the
>>>>>>>> afternoon, and have not been able to hear the noise on my portable
>>>>>>>> shortwave and loop antenna. It is as strong as ever on my home
>>>>> station.
>>>>>>>>> I have an MFJ 852 Noise Finder and it seems to
>>>>>>>>> go crazy
>>>>>>>> when broadside to any house. The neighbors on each side of me
>>>>> drive
>>>>>>>> the meter full scale.
>>>>>>>>> Yep I only want to knock on one door, as I know
>>>>>>>>> that
>>>>>>>> can get dicey. I would rather place a call to a utility, but can?t
>>>>>>>> really do either until I know.
>>>>>>>>> Keep the suggestions coming!
>>>>>>>>>
>>>>>>>>> Thanks and 73,
>>>>>>>>> Gary ?Joe? kk0sd
>>>>>>>>>
>>>>>>>>> From: Mike Martin <mike@rfiservices.com>
>>>>>>>>> Sent: Sunday, March 21, 2021 6:53 PM
>>>>>>>>> To: Gary <gary_mayfield@hotmail.com>
>>>>>>>>> Cc: rfi@contesting.com
>>>>>>>>> Subject: Re: [RFI] New Interference at kk0sd
>>>>>>>>>
>>>>>>>>> Joe I haven't had time to read all the other input but I can
>>>>> tell
>>>>>>>>> you it
>>>>>>>> is not an arcing source or a sparking source. either one of the
>>>>> two
>>>>>>>> would be much broader than what you're reporting. if someone were
>>>>>>>> to tell you exactly what it is you really wouldn't be any further
>>>>>>>> ahead. You would still have to find which residents or business
>>>>>>>> it's in. My suggestion would be to either go mobile or on foot,
>>>>>>>> preferably on foot listening to the frequency that you know the
>>>>>>>> problem affects. once you locate the residents then go through the
>>>>>>>> breaker scenario and locate what the source is. Be 100% certain of
>>>>>>>> the structure or home that the problem is in before knocking on
>>>>> the
>>>>>>>> door. The last thing you want to do is start guessing. Guessing
>>>>> we'll ruin the relationship with your neighbors.
>>>>>>>>> Be safe,
>>>>>>>>> Mike k3RFI
>>>>>>>>> www.rfiservices.com<http://www.rfiservices.com>
>>>>>>>>> Get BlueMail for Android<http://www.bluemail.me/r?b=16696>
>>>>>>>>> On Mar 21, 2021, at 2:01 PM, Gary
>>>>> <gary_mayfield@hotmail.com<mailto:
>>>>>>>> gary_mayfield@hotmail.com>> wrote:
>>>>>>>>> My last problem was tracked down to a neon sign in a neighbors
>>>>>>>>> garage. I
>>>>>>>> had several months of blissful relatively low noise operation, but
>>>>>>>> now have a new RFI issue.
>>>>>>>>> You can see a recording of it here:
>>>>>>>>> https://www.youtube.com/watch?v=GKf4P44FXMo
>>>>>>>>>
>>>>>>>>> I have turned all of the breakers in my home off and run the
>>>>>>>>> radio from
>>>>>>>> a battery and the noise remains.
>>>>>>>>> My neighborhood utilities are all underground.
>>>>>>>>>
>>>>>>>>> There are no solar installations in my neighborhood, and the
>>>>>>>>> noise is
>>>>>>>> there at night anyway...
>>>>>>>>> The noise is not detectable on the AM broadcast band, but starts
>>>>>>>>> around
>>>>>>>> 2 MHz and runs to at least 6 meters.
>>>>>>>>> It is there 7 days a week 24 hours a day.
>>>>>>>>>
>>>>>>>>> It is not detectable from my pickup when I drive the streets of
>>>>>>>>> my
>>>>>>>> neighborhood (checking both AM broadcast and Shortwave).
>>>>>>>>> If any one has heard something like this, I would love to hear
>>>>>>>>> what you
>>>>>>>> found.
>>>>>>>>> Thank You for your input and help!
>>>>>>>>>
>>>>>>>>> 73,
>>>>>>>>> Gary "Joe", kk0sd
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>>
>>>>>>>>> RFI mailing list
>>>>>>>>> RFI@contesting.com<mailto:RFI@contesting.com>
>>>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>>> _______________________________________________
>>>>>>>>> RFI mailing list
>>>>>>>>> RFI@contesting.com
>>>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>> --
>>>>>>>>
>>>>>>>> Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology,
>>>>>>>> CCM, PP SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
>>>>>>>>
>>>>>>>> /"A great second violinist plays second fiddle to no one." //?
>>>>> Robert C.
>>>>>>>> Marsh, Chicago Sun-Times./
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> RFI mailing list
>>>>>>>> RFI@contesting.com
>>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>>
>>>>>>> --
>>>>>>> *Dave - W?LEV*
>>>>>>> *Just Let Darwin Work*
>>>>>>> _______________________________________________
>>>>>>> RFI mailing list
>>>>>>> RFI@contesting.com
>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>> _______________________________________________
>>>>> RFI mailing list
>>>>> RFI@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>> _______________________________________________
>>>>> RFI mailing list
>>>>> RFI@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>> _______________________________________________
>>>> RFI mailing list
>>>> RFI@contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>
>>>
>>> ------------------------------
>>>
>>> Message: 2
>>> Date: Tue, 23 Mar 2021 15:11:11 -0400
>>> From: Don Kirk <wd8dsb@gmail.com>
>>> To: Mike Martin <mike@rfiservices.com>
>>> Cc: Gary <gary_mayfield@hotmail.com>, Kim Elmore
>>> <cw_de_n5op@sbcglobal.net>, Rfi List <rfi@contesting.com>
>>> Subject: Re: [RFI] New Interference at kk0sd
>>> Message-ID:
>>> <CAKtW65d94DMhbd3RW8eP9Q8XaiK9Y5Yr-HOiyz6rD5vqar3vhw@mail.gmail.com>
>>> Content-Type: text/plain; charset="UTF-8"
>>>
>>> Hi Mike, Gary, and gang,
>>>
>>> Well after seeing Garys shielded un-tuned loop, I watched the video on how
>>> to build that loop. I just built one almost identical to his loop but used
>>> RG-58 coax since that's what I had on hand. I also spent 10 seconds
>>> building a simple 1 turn 9 inch loop (no form, just free standing) for
>>> comparisons which is even smaller than Garys loop, and I can tell you there
>>> is no comparison. Without doing any impedance matching, the 9 inch
>>> un-tuned single turn loop I built has a gain that is approximately 23 dB
>>> greater than Garys loop when tested in the AM broadcast band and it still
>>> exhibits nice nulls which comes as no surprise. My single turn non
>>> shielded loop just has about 6 inches of twisted wire (the same wire that
>>> forms the loop) to form the feedline to it, and then I just used a 3 foot
>>> piece of 50 ohm coax to connect it to my receiver. I used the same 3 foot
>>> piece of coax to connect the shielded un-tuned loop to the receiver. While
>>> my un-tuned 9 inch loop might not be as well balanced (one null might be
>>> deeper than the opposite null), it makes one fine DF antenna in a pinch.
>>> Also if Gary needs more gain he can just make the loop I made bigger in
>>> diameter. It really just takes seconds to make this antenna (much less
>>> than a minute).
>>>
>>> I now fully understand why Gary can't hear his noise, as his un-tuned
>>> shielded loop has very poor sensitivity based on my trying to copy the
>>> design. While I normally use preamps with my DF loops, Garys RFI is so
>>> strong that I'm pretty darn sure he can make a simple one turn loop to
>>> figure out what possible directions the signal is coming from. Something I
>>> have done in the past is to use a cardboard box as the antenna form as it
>>> does not have to be round. Need to figure out what directions the signal
>>> is coming from before leaving his property if at all possible.
>>>
>>> Just my opinion, and I will try and post some comparison videos but they
>>> will not be pretty as I'm buried in other tasks.
>>>
>>> 73,
>>> Don (wd8dsb)
>>>
>>>
>>>
>>> On Tue, Mar 23, 2021 at 8:33 AM Mike Martin <mike@rfiservices.com> wrote:
>>>
>>>> Remember in his shack he has a very good radio and a very good antenna
>>>> which together increased sensitivity and allow him to hear much further
>>>> away. when he goes outside with a portable and a smaller antenna he doesn't
>>>> have the sensitivity he had inside there for he may have to travel a lot
>>>> further before he's able to receive it.
>>>>
>>>> Be safe,
>>>> Mike
>>>>
>>>> Get BlueMail for Android <http://www.bluemail.me/r?b=16696>
>>>> On Mar 22, 2021, at 11:37 PM, Gary <gary_mayfield@hotmail.com> wrote:
>>>>> Kim,
>>>>>
>>>>> I hear it on the portable when connected to the vertical antenna, but
>>>>> will undertake an antenna substitution experiment this weekend.
>>>>>
>>>>> Keep the suggestions coming!
>>>>>
>>>>> 73 and Thanks,
>>>>> Gary "Joe", kk0sd
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: RFI <rfi-bounces+gary_mayfield=hotmail.com@contesting.com> On
>>>>> Behalf Of Kim Elmore
>>>>> Sent: Monday, March 22, 2021 4:44 PM
>>>>> To: Don Kirk <wd8dsb@gmail.com>
>>>>> Cc: Rfi List <rfi@contesting.com>
>>>>> Subject: Re: [RFI] New Interference at kk0sd
>>>>>
>>>>> That?s a great idea, too! I once ran into an interference problem that
>>>>> was inherent to the antenna, but only under certain conditions. It didn?t
>>>>> sound like Gary?s but I pulled a lot of hair out fixing that one. I?m
>>>>> simply suspicious that he hears NOTHING with his portable rx so I?m after
>>>>> eliminating anything inherent to his station. Standing by his vertical
>>>>> with his portable rx is a great idea.
>>>>>
>>>>> 73,
>>>>>
>>>>> Kim N5OP
>>>>>
>>>>> "People that make music together cannot be enemies, at least as long as
>>>>> the music lasts." -- Paul Hindemith
>>>>>
>>>>> On Mar 22, 2021, at 2:24 PM, Don Kirk <wd8dsb@gmail.com> wrote:
>>>>>> ?
>>>>>> Hi Dave,
>>>>>>
>>>>>> I still recommend tuned and untuned loops to folks on an almost daily
>>>>>> basis but they definitely don?t shed as much light on the situation as a
>>>>>> unidirectional antenna does. It would be nice to see what your shielded
>>>>>> untuned loop design is.
>>>>>>
>>>>>> The beauty of the portable flag which is unidirectional is that you
>>>>>> typically can walk right to the source (no guessing which direction the
>>>>>> signal is coming from). I still pack 7 antennas when I go on a RFI
>>>>>> case, and this includes 3 tuned HF loops, but I have found that I
>>>>>> typically don?t use bidirectional loops anymore (unless I?m trying to be
>>>>>> more stealth) as the portable flag saves me an enormous amount of time.
>>>>>> Also in heavily congested areas (like downtown Indianapolis) having the
>>>>>> unidirectional HF antenna is priceless as it unmasks noise that?s mixing
>>>>>> from other sources that are in the opposite direction, etc. Yesterday I
>>>>>> worked on a case (more of a country setting) where I had 2 different bad
>>>>>> poles that were only 0.14 miles apart plus a 3rd RFI source generating
>>>>>> spikes every 1 KHz within the same area and having the unidirectional HF
>>>>>> antenna helped me locate all 3 sources in a matter of minutes (way under
>>>>>> an hour).
>>>>>>
>>>>>> You can never have enough antennas in your direction finding bag of
>>>>>> tricks but after using a unidirectional HF antenna like the portable
>>>>>> flag for direction finding I can?t imagine not using one. It typically
>>>>>> takes me seconds to tell which direction the signal is without the need
>>>>>> of triangulation, etc. Traditional triangulation has almost become a
>>>>>> thing of the past for me.
>>>>>>
>>>>>> I also have been helping a ham that has the MFJ unit (the one with a
>>>>>> beam and the one with a dipole) and while it has helped him, it has an
>>>>>> odd characteristic that makes the meter jump which causes confusion to
>>>>>> him and after looking at the schematic I question how they implemented
>>>>>> AGC in those units. I?m starting to think AGC in a radio direction
>>>>>> finding system is typically not desirable. Manual attenuation is
>>>>>> priceless but I don?t want anything changing gain automatically.
>>>>>>
>>>>>> Just my opinion from tracking down RFI on an almost continuous basis in
>>>>>> addition to my day job.
>>>>>>
>>>>>> Please share details on your shielded untuned loop and thanks.
>>>>>>
>>>>>> 73,
>>>>>> Don wd8dsb
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Mar 22, 2021 at 1:22 PM David Eckhardt <davearea51a@gmail.com>
>>>>>> wrote:
>>>>>>> We recently found a faulty lightning 'arrestor' on a pole by using
>>>>>>> both the MFJ device and a small shielded loop (easy home brew
>>>>>>> project) into a battery-powered receiver. We had two of us in the
>>>>>>> field. One wielded the MFJ and I had the small (0.5-meter) shielded
>>>>>>> loop fed into the Yaesu VR-500 on 1.830 MHz (160-meters). We both
>>>>>>> independently found the same source / pole in the field. The null on
>>>>>>> the shielded loop is extremely sharp and this piece of hardware
>>>>>>> should be in the bag of tricks of anyone sleuthing RFI. It is a
>>>>>>> powerful tool when coupled to a battery-powered receiver with its
>>>>>>> extremely sharp null (perpendicular to the plane of the loop). One
>>>>>>> doesn't need something as large as the 'Flag" that was recently
>>>>>>> published
>>>>>>> in QST and referred to in a previous post in this thread. Another plus
>>>>>>> for the shielded loop is that in the field, one can tune the receiver
>>>>>>> to the worst-case frequency of the RFI as I did in the related story,
>>>>>>> above.
>>>>>>> The shielded loop is untuned. The MFJ relies only on VHF noise. In
>>>>>>> some
>>>>>>> cases, an ultrasonic microphone at the focus of a small parabolic or
>>>>>>> spherical reflector is good at finding coronal discharges as well as
>>>>>>> active arcs and discharges. MFJ also makes that at a reasonable price.
>>>>>>>
>>>>>>> Our power provider was out the next day to fix the problem. We even
>>>>>>> gave them the pole number which is a great help to any power provider.
>>>>>>>
>>>>>>> Dave - W?LEV
>>>>>>>
>>>>>>> On Mon, Mar 22, 2021 at 2:28 AM Kim Elmore <cw_de_n5op@sbcglobal.net>
>>>>>>> wrote:
>>>>>>>
>>>>>>> It's odd that you can't hear it on your portable rx. That made me
>>>>>>>> curious: What if this is something internal to your '847? Have you
>>>>>>>> tried pulling your '847 and listening on a different receiver using
>>>>>>>> the same antenna? If you have, do you still hear the noise? It's a
>>>>>>>> long shot, but...
>>>>>>>>
>>>>>>>> Kim N5OP
>>>>>>>>
>>>>>>>> On 3/21/2021 7:28 PM, Gary wrote:
>>>>>>>>
>>>>>>>>> Mike,
>>>>>>>>>
>>>>>>>>> Thanks for the info. I understand locating the
>>>>>>>>> noise is
>>>>>>>>>
>>>>>>>> more important than identifying the noise. I am just try to play
>>>>>>>> all the angles as I was hoping to work the WPX contest nest
>>>>>>>> weekend. I have been walking the neighborhood a good chunk of the
>>>>>>>> afternoon, and have not been able to hear the noise on my portable
>>>>>>>> shortwave and loop antenna. It is as strong as ever on my home station.
>>>>>>>>
>>>>>>>>> I have an MFJ 852 Noise Finder and it seems to
>>>>>>>>> go crazy
>>>>>>>>>
>>>>>>>> when broadside to any house. The neighbors on each side of me drive
>>>>>>>> the meter full scale.
>>>>>>>>
>>>>>>>>> Yep I only want to knock on one door, as I know
>>>>>>>>> that
>>>>>>>>>
>>>>>>>> can get dicey. I would rather place a call to a utility, but can?t
>>>>>>>> really do either until I know.
>>>>>>>>
>>>>>>>>> Keep the suggestions coming!
>>>>>>>>>
>>>>>>>>> Thanks and 73,
>>>>>>>>> Gary ?Joe? kk0sd
>>>>>>>>>
>>>>>>>>> From: Mike Martin <mike@rfiservices.com>
>>>>>>>>> Sent: Sunday, March 21, 2021 6:53 PM
>>>>>>>>> To: Gary <gary_mayfield@hotmail.com>
>>>>>>>>> Cc: rfi@contesting.com
>>>>>>>>> Subject: Re: [RFI] New Interference at kk0sd
>>>>>>>>>
>>>>>>>>> Joe I haven't had time to read all the other input but I can tell
>>>>>>>>> you it
>>>>>>>>>
>>>>>>>> is not an arcing source or a sparking source. either one of the two
>>>>>>>> would be much broader than what you're reporting. if someone were
>>>>>>>> to tell you exactly what it is you really wouldn't be any further
>>>>>>>> ahead. You would still have to find which residents or business
>>>>>>>> it's in. My suggestion would be to either go mobile or on foot,
>>>>>>>> preferably on foot listening to the frequency that you know the
>>>>>>>> problem affects. once you locate the residents then go through the
>>>>>>>> breaker scenario and locate what the source is. Be 100% certain of
>>>>>>>> the structure or home that the problem is in before knocking on the
>>>>>>>> door. The last thing you want to do is start guessing. Guessing we'll
>>>>>>>> ruin the relationship with your neighbors.
>>>>>>>>
>>>>>>>>> Be safe,
>>>>>>>>> Mike k3RFI
>>>>>>>>> www.rfiservices.com<http://www.rfiservices.com>
>>>>>>>>> Get BlueMail for Android<http://www.bluemail.me/r?b=16696>
>>>>>>>>> On Mar 21, 2021, at 2:01 PM, Gary <gary_mayfield@hotmail.com<mailto:
>>>>>>>>>
>>>>>>>> gary_mayfield@hotmail.com>> wrote:
>>>>>>>>
>>>>>>>>> My last problem was tracked down to a neon sign in a neighbors
>>>>>>>>> garage. I
>>>>>>>>>
>>>>>>>> had several months of blissful relatively low noise operation, but
>>>>>>>> now have a new RFI issue.
>>>>>>>>
>>>>>>>>> You can see a recording of it here:
>>>>>>>>> https://www.youtube.com/watch?v=GKf4P44FXMo
>>>>>>>>>
>>>>>>>>> I have turned all of the breakers in my home off and run the
>>>>>>>>> radio from
>>>>>>>>>
>>>>>>>> a battery and the noise remains.
>>>>>>>>
>>>>>>>>> My neighborhood utilities are all underground.
>>>>>>>>>
>>>>>>>>> There are no solar installations in my neighborhood, and the
>>>>>>>>> noise is
>>>>>>>>>
>>>>>>>> there at night anyway...
>>>>>>>>
>>>>>>>>> The noise is not detectable on the AM broadcast band, but starts
>>>>>>>>> around
>>>>>>>>>
>>>>>>>> 2 MHz and runs to at least 6 meters.
>>>>>>>>
>>>>>>>>> It is there 7 days a week 24 hours a day.
>>>>>>>>>
>>>>>>>>> It is not detectable from my pickup when I drive the streets of
>>>>>>>>> my
>>>>>>>>>
>>>>>>>> neighborhood (checking both AM broadcast and Shortwave).
>>>>>>>>
>>>>>>>>> If any one has heard something like this, I would love to hear
>>>>>>>>> what you
>>>>>>>>>
>>>>>>>> found.
>>>>>>>>
>>>>>>>>> Thank You for your input and help!
>>>>>>>>>
>>>>>>>>> 73,
>>>>>>>>> Gary "Joe", kk0sd
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ------------------------------
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> RFI mailing list
>>>>>>>>> RFI@contesting.com<mailto:RFI@contesting.com>
>>>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>>> ------------------------------
>>>>>>>>>
>>>>>>>>> RFI mailing list
>>>>>>>>> RFI@contesting.com
>>>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>>>
>>>>>>>> --
>>>>>>>>
>>>>>>>> Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology,
>>>>>>>> CCM, PP SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
>>>>>>>>
>>>>>>>> /"A great second violinist plays second fiddle to no one." //? Robert
>>>>>>>> C.
>>>>>>>> Marsh, Chicago Sun-Times./
>>>>>>>>
>>>>>>>> ------------------------------
>>>>>>>>
>>>>>>>> RFI mailing list
>>>>>>>> RFI@contesting.com
>>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> *Dave - W?LEV*
>>>>>>> *Just Let Darwin Work*
>>>>>>> ------------------------------
>>>>>>>
>>>>>>> RFI mailing list
>>>>>>> RFI@contesting.com
>>>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>>>
>>>>>> ------------------------------
>>>>> RFI mailing list
>>>>> RFI@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>> ------------------------------
>>>>>
>>>>> RFI mailing list
>>>>> RFI@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>>>
>>>>>
>>>
>>> ------------------------------
>>>
>>> Subject: Digest Footer
>>>
>>> _______________________________________________
>>> RFI mailing list
>>> RFI@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/rfi
>>>
>>>
>>> ------------------------------
>>>
>>> End of RFI Digest, Vol 218, Issue 27
>>> ************************************
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>
> --
> They say a smart person learns from their mistakes. A
> wise person learns from the mistakes of others.
>
>
>
> --
> This email has been checked for viruses by AVG.
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>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
>
> ------------------------------
>
> End of RFI Digest, Vol 218, Issue 29
> ************************************
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