[SCCC] RF Noise

Fri Feb 15 07:19:52 EST 2019

Wyatt, Prada’s and Wolf really hit it with great information.
I’ve recently been hunting down my noise too. I was able to fix my problems for an SO1R station at home in 2012 with similar methods that they have given to you.
Now in 2018, I had finally decided to fix problems that come up with SO2R and that gets even worse usually whenever you have a multi transmitter environment. I found that power supplies from my computers, wall warts, etc. were sometimes and on some band combinations causing re-radiation issues. The noise was bad enough that it was causing my RX to suffer slightly to tremendously depending on many factors. Suffice it to say I needed to buy many more beads and toroids as discussed already.
What I found would lead me to suggest that you attack your father’s computer with the first eye on his power supply unit’s AC cord. With enough clamp on beads I was able to eliminate one of my computer PSUs from the problem list. I would have used a core or many with the AC cable wrapped through them had a number of beads not worked. 
I further found that some beads snapped on at the wall end of that PSU AC cord helped with other band or antenna heading combinations.
It could be any wire associated with his computer that you need to go after with ferrite or quality upgrades as suggested. You may even find the monitor or PSU is so bad it needs to be replaced when enough ferrite isn’t going to fix things, but that would be the last resort in my mind. The good thing is that you know what and where your problem is... now it’s time to test one cable out then the next.
Start with one bead or toriod and then more. Leave them on each wire as you progress. After you solve the problem, if you want, you can come back and remove one bead / toroid at a time while watching your Icom across ALL bands each step.
I say this because while you fix one problem you might cause another. I have found that when I clamp one problem I might cause something else on another band. 
So order up, take your time testing, and at each step check each band. Also, switch between antennas and rotate too if you have these options.
You’ll get this fixed no problem if you follow the advice already given. And worse case you might have a PSU or something to go shoot somewhere safe.
Tim / N6WIN 

Sent from Yahoo Mail for iPhone

On Friday, February 15, 2019, 02:03, Prasad VU2PTT <vu2ptt at gmail.com> wrote:

Wyatt,

You may also want to look at the new ferrite cookbook from K9YC which could give you more bang with less ferrite - http://k9yc.com/2018Cookbook.pdf

73,

Prasad VU2PTT, W2PTT (ex AF6DV)

Sent from my iPhone

> On 15-Feb-2019, at 11:11 AM, Wolf Leverich, WA6I <leverich at mtpinos.com> wrote:
> 
> 
> Hi Wyatt -
> 
> Several comments:
> 
> Ferrite toroids are your friend.  I buy them in $100 lots from Kreger
> Components -- usually Mix 31 1.5"ID/2.5"OD toroids, Fair-rite 2631803802.
> 
> Note that choking resistance increases roughly with the square of the
> number of turns until you get into capacitive bleed and resonance issues,
> so you really, really want multiple turns if at all possible.
> 
> At least to a point.
> 
> 8-13 turns will put a real dent in any common-mode hash on a pair of
> wires.  (Don't do more than 13T, unless you want to sacrifice choking
> on the higher end of the HF spectrum for more on the lower -- and even
> then, you might want to use a different ferrite mix if you're a Top Band
> contester.)
> 
> If you can't get 13T through the toroid, you can use more toroids.  A
> famous coax choke is only something like 3 turns through two stacks of
> 4 toroids.
> 
> Wall warts apparently aren't your problem, but you can choke their AC
> side by buying a 6' 2-conductor extension cord at Home Depot, winding
> it around a toroid, then inserting that between the wall wart and the
> outlet.
> 
> Besides ferrites, be aware that cables matter.  Some cheap HDMI and
> USB cables are pretty efficient noise antennas.  Toroids will help
> but a better idea is to buy better cables and then choke them.
> 
> Also, Faraday cages can be your friend.  Be aware that a Faraday cage
> needs to have walls (rule of thumb) 20x the skin depth of the signal
> you want to block, so aluminum foil isn't effective at HF.  But cookie
> sheets and even disposable turkey pans are.  Also, aluminum window
> screening usually is.  If you can box the noise source, that will help.
> 
> Another thing that matters is station grounding.  That's a whole
> topic unto itself.
> 
> BTW, in my experience DX Engineering Maxi-Core® feedline current chokes
> DXE-FCC050-H05-B totally rock if you have noise coming in on your feedline.
> 
> Be aware that feedline noise ingress, if I understand what's happening
> here, really comes in 3 flavors: feedline to your rig, feedline to your
> antenna, and feedline leakage in between.  Burying your coax helps
> with everything, and choking it at both your rig and antenna helps.
> 
> And I apologize for the sorta-random core dump.  It's been a long day
> in a really, really long week and my caffeine reserves are totally 
> depleted. hihihihi
> 
> 73 de Wolf WA6I
> 
> 
> 
> 
> 
>> On Thu, Feb 14, 2019 at 09:00:13PM -0800, Wyatt Law wrote:
>> Hello all,
>> 
>> I was wondering what everyone else uses to cut down on noise. I used to
>> have a problem where whenever I did CW, it would turn off the TVs in my
>> house and make my PC monitor flicker. That has been fixed for a while with
>> ferrite beads. The only issue that I have now is that whenever my dad's PC
>> is turned on across the house, it blows out my IC-7300. It makes a ton of
>> noise all over the panadapter and significantly raises the noise level.
>> When the PC is turned off, the noise is gone. What could be done to stop
>> this? I've read online that people wrap their cables in torrids? If so what
>> size and where should I get them? I have tired different combinations of
>> beads and looping the coax with no change and was wondering if anyone has
>> had any success with torrid wrapping?
>> 
>> Thanks,
>> Wyatt
>> AI6V
>> wyattlaw4 at gmail.com
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