[RFI] Home RFI Hunting

[Dave Van Wallaghen]

Hey Jim,

Sorry for the delay, I had to go back into work yesterday and just never 
found time to sit down and reply. I completely agree with every issue you 
raised and have implemented some of what you suggested as well as things 
you've mentioned over the years. I did fail to provide any background as to 
what my setup is and what I'm trying to accomplish.

Rest assured, I have no grand illusions as to what that mutli-band end fed 
antenna is and how it performs. I bought it a couple of years ago as an 
emergency backup antenna because it is easily deployable and it doesn't 
require great height to provide a reasonable match to my rig when used in a 
pinch. You are absolutely right in that I could have built something 
similar. In fact, I have always built all my wire antennas to date whether 
dipoles or ladder line fed doublets that I used as multi-band setups and 
enjoy doing so. This end fed came as a recommendation from a couple of 
other fellow hams who are kind of using it in the same fashion. I have not 
used it for any type of operating, just listening and testing.

Unfortunately, my time is very limited between job, family and taking care 
of aging parents, so I don't operate nearly as often as I would like. I 
work as a career fire fighter/medic here and have a little over 2.5 years 
to go until I can retire. I won't retire - retire, but I will stop beating 
up my body and mind in this gig ;-) So, I have kind of resolved myself to 
getting my own backyard in order here in preparation for a future time when 
I can devote resources to implementing satisfactory antenna systems to 
really enjoy the hobby and give my K3 & K2 something worthwhile to work with.

With all that said, I am just using that multi-band end fed as a sniffer 
antenna for my local noise in order to kill what I can. I have the fed end 
mounted near (attached to an eve) a corner of the house and running out to 
a tree in the backyard. It is picking up my local noise very well. I have 
been able to identify multiple sources using my K3/P3. Since I'm a one man 
operation here (ok I've used my wife a couple of times to help out, but it 
is not fun for her), I moved my K3/P3 upstairs into the kitchen about 20 
feet from my breaker box in the garage. I routed the coax through the 
kitchen sliding door and put the rig on a battery. This simplified setup 
provided me with a good way to hunt and eliminate noise sources one at a 
time (as you stated in the KillingReceiveNoise pdf). Most of the time I 
could just turn up the volume a little and go out a flip breakers until I 
found the noisy circuit.  This simplified setup also allowed me to obtain 
repeatable baseline noise measurements on all bands 160m-10m and see if 
there were any changes at different times of the day. I've been keeping a 
journal to document all of my readings and findings.

I have implemented the grounding and bonding techniques you have described 
in my shack. (I have the N0AX book as well). The one thing I haven't done 
yet is implement a lightning ground scheme although I have much of the 
material. My breaker panel and AC feed is on the opposite side of the house 
from my basement shack. My AC ground connection is the green wire back to 
the panel at this point. I do not, and will not, put a ground rod outside 
my shack until I know I can properly bond the service ground and shack 
lightning ground properly. (Hopefully a near term project). The long run 
back to the panel may well represent some of the noise I'm seeing in the 
bottom end of the AM band.

I do have one of those circuit testers you described and did test the two 
circuits I have in the basement and my AV/TV circuit - all tested good. 
This morning when I got off duty, I went around the whole house and tested  
all circuits and everything looks good.

I would like to listen in on 600m although I have no decent antenna to do 
so. I'm being more anal about killing the noise just because, I suppose. I 
did listen in on a portable vertical dipole set up for 40m. It has a W2DU 
balun at the feedpoint and while I can hear AM stations all the way down to 
 540Khz, I'm sure it is severely detuned down there. But I don't hear that 
buzzing noise nearly as much as I do with the end fed. So again, I'm 
thinking that the coax shield acting as a counterpoise is coupling the 
noise when connected to the AC ground system. This is  not a show stopper, 
just being anal and learning ;-)

I have eliminated many noise sources so far and will concentrate on the 
remaining sources that seem to be pretty heavy on 20m and 10m. I cleaned 
40m up very well through use of #31 cores on problem appliances or 
replacing the power source. Right now, my biggest contributors to just 
elevated noise level throughout the entire 20m band and 10m band are the 
wall warts powering my Comcast cable boxes in my living room (HD, DVW etc) 
and a small HD box in my bedroom. I don't have any junk linear wall warts 
with high enough current capabilities for those (2.67A and 1.5 A 
respectfully). I'm going to try the trick of plugging them into a short 
extension cord and choking the cord.

Your story of your house reminded me that I had cut through my cable line 
out in the yard digging up a bush. When the tech came out to replace it, I 
asked her why the cable was not grounded at my AC entry and that I was 
worried about not having a single ground point at the entrance. She looked 
at it and said I was absolutely right and that the prior installation was 
incorrect and set it up properly for me. Now I just need to tie my shack 
ground in and I'll be in business.

Thanks for all your advice and the ongoing effort you put in on the various 
lists we subscribe. And thanks to all the replies I've received from all 
the list members. The advice is very much appreciated as I continue to 
learn and progress.

73,
Dave W8FGU


On September 30, 2018 13:58:27 Jim Brown <jim at audiosystemsgroup.com> wrote:

> GM Dave,
>
> There are many elements to your problem, one of which may be your choice
> of antennas. I'll begin with this. SWR IS NOT A MEASURE OF ANTENNA
> PERFORMANCE!  What matters are the EFFICIENCY of the antenna for
> transmitting, the directional pattern in three dimensions, the ability
> to HEAR other stations, and match between the rig and antenna so that it
> accepts power.  SWR, as measured in the shack, describes ONLY the last
> of those factors.  The company selling the antenna you have selected
> says NOT A WORD about anything but SWR, and I saw nothing on their
> website telling me anything about any matching network built into their
> "black box." FWIW, $185 is a lot to spend on 130 ft of wire and a magic
> box, which I would guess is most likely a transformer wound on some form
> of ferrite or powdered iron core.  $41 will get me 500 ft of wire, a
> suitable core costs less than $10.
>
> Second: Sadly, it is quite common for we hams to be surrounded by noise
> sources, some of which are under our control and some of which are not.
> Those noise sources in your living room ARE under your control, and you
> should address them first. Study
> http://k9yc.com/KillingReceiveNoise.pdf in text form, and
> http://k9yc.com/KillingRXNoiseVisalia.pdf as slides for a talk at
> Visalia a year or two ago.
>
> Third, I strongly suggest that you STUDY and IMPLEMENT proper BONDING in
> your home and station as described in my tutorial slide show on the
> topic, and as described in N0AX's ARRL book on Grounding and Bonding.
>
> Fourth, do you plan to operate (or listen seriously) on the new 630m
> band or on the AM broadcast band? ONLY if the answer is Yes should you
> choke noise sources in that frequency range.  While many (most?) noise
> sources are broadband (that is, extending from very low to very high
> frequencies), we only need to choke them in the frequency range(s) where
> we want to hear weak signals.
>
> Fifth, the smartest hams who seriously want to operate or listen on
> bands below 30m use some form of receiving loop antenna to minimize
> noise. And this is AFTER they have put in serious effort to kill as many
> noise sources as possible.
>
> As to your question about multiple chokes -- Dave has given you the
> right answer, but unless you want to seriously listen below 160M,
> Fair-Rite #31 material is the only good choice.
>
> I also suggest that you check the wiring of all the AC outlets in your
> home, especially those to which anything is plugged in. Outlets are
> wired by human beings, and we, as a species screw up now and then. There
> are inexpensive outlet testers that will expose most wiring errors. A
> decent AC voltmeter will also do the job, but takes longer. I found two
> mis-wired outlets in the home I bought in W6 twelve years ago, and
> MULTIPLE serious errors in grounding and bonding of the AC power system
> that caused my house wiring to radiate noise coupled from the outside
> power line!
>
> The most serious issue was that the "ground" wire for the AC power,
> telephone, and CATV went to a water hose faucet 40 ft from the power
> entry, AND that faucet was fed by PVC pipe!  The result was that the
> only ground in my home was the rod driven for my ham station, which is
> in the separate garage-apartment where my ham station is set up. In
> addition to being illegal and unsafe, this wiring error caused noise
> from outside power lines to go to ground through my ham station, which
> made the ham bands VERY noisy!
>
> 73, Jim K9YC
>
> On 9/30/2018 8:31 AM, Dave Van Wallaghen wrote:
>> First, thanks to all of you who replied on the list and privately. I
>> appreciate all the advise.
>>
>> I just wanted to follow up on this as I tried a few things and I
>> sheepishly bring the solution to my buzzing noise problem on the low
>> end of the AM band and 600m in case anyone else runs into my situation.
>>
>> I did run a separate AC ground back to the panel physically separating
>> my shack circuit from my problematic AV/TV circuit. This had no effect
>> what so ever. So while pondering why this noise is so prominent if my
>> antenna or rig is connected to the AC ground system, my inexperience
>> waned enough that I finally figured out what was going on. In my first
>> email, I failed to mention that the antenna I was using is a 80-10m
>> multi-band end fed from MyAntennas. This seemed like a logical choice
>> since it is resonant on all of the ham bands I wanted to test and does
>> fairly well on 160m and 600m as well.
>>
>> So yes, the coax shield of the feedline of the antenna acts as the
>> counterpoise for this antenna, and in effect, everytime I connected
>> the AC ground to the rig or antenna ground, it was coupling the noise
>> directly to my antenna system and rig. Several turns of the feedline
>> through a #31 core at the rig end greatly reduces the buzzing. It
>> reduced the noise for S9+5 to a respectful S5-6 which is what I was
>> seeing when I floated the ground of the rig and antenna. I still have
>> a little noise between 380-480Khz that I will tweak and see if I can
>> eliminate all together.
>>
>> This leads to my next question: I was thinking of using a #77 mix core
>> in series with the #31 to help here as the #77 has a higher impedance
>> in the lower frequencies. I may have missed it in Jim, K9YC's RFI pdf,
>> but does series mean the two cores together with the cable passing
>> through them simultaneously? Or two separately wound cores? I
>> apologize if this is a dumb question. I've learned a great deal
>> throughout this process and I might just be a little overloaded at the
>> moment ;-)
>>
>> 73,
>> Dave W8FGU
>>
>>
>>
>>
>> On September 13, 2018 14:23:44 Jim Brown <jim at audiosystemsgroup.com>
>> wrote:
>>
>>> On 9/13/2018 10:36 AM, Dave Van Wallaghen wrote:
>>>> So, my questions are: as the largest portion of this noise comes from
>>>> my TV plugged into the AV circuit, would running separate grounds for
>>>> my AV and shack circuits back to the panel help alleviate some of the
>>>> noise that I find on my shack circuit ground? Or do you think most of
>>>> it is being physically coupled? I would have tried this myself, but
>>>> while certainly doable, it will be a little work to make it happen.
>>>
>>>
>>> Several thoughts on this.
>>>
>>> First, RF noise from defective/poorly designed equipment OFTEN travels
>>> on the green wire, so yes, separate green wires is a good thing.
>>>
>>> Second, chokes to kill noise currents need to be tuned to the
>>> frequency(ies) where you are bothered by the interference. While PROBING
>>> for noise sources at lower frequencies can be effective, there's no need
>>> to choke those frequencies unless you use your radio there.
>>>
>>> Third, if the TV is a noise source, I would choke every cable connected
>>> to it, starting with those that are likely to be the most effective
>>> radiators, first the power cable and coax feeding it, then audio and
>>> video cables if there are any.
>>>
>>>>
>>>> I also read on the Polamar website about using #75 mix Clamp On cores
>>>> for use on frequency ranges down to 200 kHz. Is this something
>>>> applicable to my problem?
>>>
>>> Only if you need to kill noise on the new 630M band, and only if you
>>> wind a lot of turns. Simply clamping one or more of them onto cables is
>>> unlikely to do much.
>>>
>>> I'm surprised that you're hearing a lot of noise coming from an LCD TV.
>>> The most likely source would be a poorly filtered switch-mode power
>>> supply built into it. I would also look for other sources around the TV,
>>> like switch-mode wall warts for various equipment, or built into other
>>> equipment.
>>>
>>> 73, Jim K9YC
>>>
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>>
>>
>>
>
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