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RFI/EMI and dealing with it

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Joshua Gould, K8WXA

RFI/EMI and dealing with it

Greetings,

I am the relatively new owner of a KX3 and I've discovered somewhat of a
problem: The switching power supplies that supply power to at least my
laptop, an external display, the router, the desk lamp and possibly my
speakers create S5-7 noise on all bands and S9 noise on some of them.

I unplugged the power cable that controls the desk and the noise dropped to
an S1-2. I plugged the main power cord back in and then started by
unplugging individual items, keeping track of what I was plugging in and
what the noise level was like.

I placed an order on Amazon for some snap on ferrite beads and they should
be here today. Having never had to track down the source of noise like
this, I am unsure of where to place the beads to have the maximum effect to
clear up the signals so I can enjoy operating from home...

I'll add that I first noticed the high amounts of noise after I had strung
up a wire inside the office because something had happened to my G5RV on
the roof. I am suspecting bad coax on the G5RV as I have it working by
playing with the coax. Neither of the PL-259s on my Comet CTC-50 window
passthrough jumper (Landlord and XYL say no holes in the house.. :() are
tightened down and I can hear stations in the noise. Tighten them down and
I get silence. If I unplug the antenna from the side of the KX3, I get
silence (well, unless the volume is up in the 30's or higher and I have the
speakers connected) I can still hear noise but it doesn't register on the S
meter.

If anyone could help out a still somewhat new General with this, it would
be appreciated.

72,
Joshua Gould
K8WXA
EM89pn

KX3# 7480
NAQCC # 7704
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KEN-3

Re: RFI/EMI and dealing with it

Switching power supplies can generate a lot of RFI if not properly designed and filtered (can you say “lowest cost chinese bidder"?). The little wall-warts are often switching supplies and often poorly filtered. If they are your problem (easy to tell by unplugging them), you can replace them with better warts, or, if they are 12v, run them off of your main 12v supply.

Ferrite beads might help, I would place them close to the wart itself.

One of the best ways to tell if the noise is from inside your house is to run the rig off of battery power and throw the main breakers. If the noise drops, then you can hunt within your own domain. But if the noise remains, then it is external to your home.

I’ve done the battery op trick here and the noise did not change, it’s incoming on the power line.

Ken WA8JXM

> On Feb 25, 2015, at 10:00 AM, Joshua Gould <[hidden email]> wrote:
>
> Greetings,
>
> I am the relatively new owner of a KX3 and I've discovered somewhat of a
> problem: The switching power supplies that supply power to at least my
> laptop, an external display, the router, the desk lamp and possibly my
> speakers create S5-7 noise on all bands and S9 noise on some of them.
>
> I unplugged the power cable that controls the desk and the noise dropped to
> an S1-2. I plugged the main power cord back in and then started by
> unplugging individual items, keeping track of what I was plugging in and
> what the noise level was like.
>
> I placed an order on Amazon for some snap on ferrite beads and they should
> be here today. Having never had to track down the source of noise like
> this, I am unsure of where to place the beads to have the maximum effect to
> clear up the signals so I can enjoy operating from home...
>
> I'll add that I first noticed the high amounts of noise after I had strung
> up a wire inside the office because something had happened to my G5RV on
> the roof. I am suspecting bad coax on the G5RV as I have it working by
> playing with the coax. Neither of the PL-259s on my Comet CTC-50 window
> passthrough jumper (Landlord and XYL say no holes in the house.. :() are
> tightened down and I can hear stations in the noise. Tighten them down and
> I get silence. If I unplug the antenna from the side of the KX3, I get
> silence (well, unless the volume is up in the 30's or higher and I have the
> speakers connected) I can still hear noise but it doesn't register on the S
> meter.
>
> If anyone could help out a still somewhat new General with this, it would
> be appreciated.

______________________________________________________________
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Eduardo González

Re: RFI/EMI and dealing with it

Hi Joshua.
I suggest using EMI/RFI filters in a box. For example, Corcom 10VR1
into a metallic box with male and female AC outlets to connect AC
power of PCs, Laptop, etc. Preferably, the length of power cord from
box to equipment must be short as possible.

Edu YV4GMJ

On Wed, Feb 25, 2015 at 10:46 AM, Ken <[hidden email]> wrote:

> Switching power supplies can generate a lot of RFI if not properly designed and filtered (can you say “lowest cost chinese bidder"?). The little wall-warts are often switching supplies and often poorly filtered. If they are your problem (easy to tell by unplugging them), you can replace them with better warts, or, if they are 12v, run them off of your main 12v supply.
>
> Ferrite beads might help, I would place them close to the wart itself.
>
> One of the best ways to tell if the noise is from inside your house is to run the rig off of battery power and throw the main breakers. If the noise drops, then you can hunt within your own domain. But if the noise remains, then it is external to your home.
>
> I’ve done the battery op trick here and the noise did not change, it’s incoming on the power line.
>
> Ken WA8JXM
>
>
>> On Feb 25, 2015, at 10:00 AM, Joshua Gould <[hidden email]> wrote:
>>
>> Greetings,
>>
>> I am the relatively new owner of a KX3 and I've discovered somewhat of a
>> problem: The switching power supplies that supply power to at least my
>> laptop, an external display, the router, the desk lamp and possibly my
>> speakers create S5-7 noise on all bands and S9 noise on some of them.
>>
>> I unplugged the power cable that controls the desk and the noise dropped to
>> an S1-2. I plugged the main power cord back in and then started by
>> unplugging individual items, keeping track of what I was plugging in and
>> what the noise level was like.
>>
>> I placed an order on Amazon for some snap on ferrite beads and they should
>> be here today. Having never had to track down the source of noise like
>> this, I am unsure of where to place the beads to have the maximum effect to
>> clear up the signals so I can enjoy operating from home...
>>
>> I'll add that I first noticed the high amounts of noise after I had strung
>> up a wire inside the office because something had happened to my G5RV on
>> the roof. I am suspecting bad coax on the G5RV as I have it working by
>> playing with the coax. Neither of the PL-259s on my Comet CTC-50 window
>> passthrough jumper (Landlord and XYL say no holes in the house.. :() are
>> tightened down and I can hear stations in the noise. Tighten them down and
>> I get silence. If I unplug the antenna from the side of the KX3, I get
>> silence (well, unless the volume is up in the 30's or higher and I have the
>> speakers connected) I can still hear noise but it doesn't register on the S
>> meter.
>>
>> If anyone could help out a still somewhat new General with this, it would
>> be appreciated.
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Jim Brown-10

Re: RFI/EMI and dealing with it

In reply to this post by Joshua Gould, K8WXA

Hi Joshua,

Several years ago, I wrote a tutorial on RFI and how to deal with it.
k9yc.com/RFI-Ham.pdf

73, Jim K9YC

On Wed,2/25/2015 7:00 AM, Joshua Gould wrote:

> Greetings,
>
> I am the relatively new owner of a KX3 and I've discovered somewhat of a
> problem: The switching power supplies that supply power to at least my
> laptop, an external display, the router, the desk lamp and possibly my
> speakers create S5-7 noise on all bands and S9 noise on some of them.
>
> I unplugged the power cable that controls the desk and the noise dropped to
> an S1-2. I plugged the main power cord back in and then started by
> unplugging individual items, keeping track of what I was plugging in and
> what the noise level was like.
>
> I placed an order on Amazon for some snap on ferrite beads and they should
> be here today. Having never had to track down the source of noise like
> this, I am unsure of where to place the beads to have the maximum effect to
> clear up the signals so I can enjoy operating from home...
>
> I'll add that I first noticed the high amounts of noise after I had strung
> up a wire inside the office because something had happened to my G5RV on
> the roof. I am suspecting bad coax on the G5RV as I have it working by
> playing with the coax. Neither of the PL-259s on my Comet CTC-50 window
> passthrough jumper (Landlord and XYL say no holes in the house.. :() are
> tightened down and I can hear stations in the noise. Tighten them down and
> I get silence. If I unplug the antenna from the side of the KX3, I get
> silence (well, unless the volume is up in the 30's or higher and I have the
> speakers connected) I can still hear noise but it doesn't register on the S
> meter.
>
> If anyone could help out a still somewhat new General with this, it would
> be appreciated.
>
> 72,
> Joshua Gould
> K8WXA
> EM89pn
>
> KX3# 7480
> NAQCC # 7704
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>