VERY noisy LCD Monitor. Any Suggestions?

[Jim KO5V]

Good afternoon,

I have a ~24" LCD monitor that I want to use for logging, to display my panadapter, etc. Unfortunately, it is very noisy on HF. When It goes to sleep, the noise goes away. This is even more irritating because I now have the K2/computer/logging, etc, all working together. I've searched a bit on-line, but so far, I have not found any real solutions (but a lot of "me too" answers, and one suggestion to ditch the radio and make use of the internet...).

There are what look to be ferrite beads on each end of the signal cable from the computer to the monitor, and on the monitor end of the power supply's low-voltage line (I assume it's a switching supply). There are no beads on the supply's power cord.

All the radio equipment and the computer are using the same AC circuit. The rig and amp are grounded to the station ground, but the computer and monitor are only grounded through the AC supply.

I have four clip-on ferrite beads that I've tried on each end of the monitor's two lines, and they make no difference.

Does anyone have any suggestions? Maybe I've missed something dumb. I don't mind getting some big cores if necessary, but I would like to hear of someone's success before spending a lot of money trying to "shotgun" the solution, and I really don't want to get a new monitor - but if anyone has a suggestion of a noise-free one, please let me know.

Thanks in advance. 73,

Jim KO5V
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[Nicklas Johnson]

My experience with some cheaper LCD monitors is that the backlight
brightness is controlled by a badly designed PWM circuit.  With my parents'
Samsung, the noise is even audible if you're sitting next to it.

The only solution I've found, if indeed this is what's giving you trouble,
is to turn the backlight brightness up to 100%.  Even at 99% the PWM kicks
in and makes a hell of a racket.

   Nick


On Sun, 26 May 2019 at 12:16, Jim KO5V <[hidden email]> wrote:

> Good afternoon,
>
> I have a ~24" LCD monitor that I want to use for logging, to display my
> panadapter, etc. Unfortunately, it is very noisy on HF. When It goes to
> sleep, the noise goes away. This is even more irritating because I now have
> the K2/computer/logging, etc, all working together. I've searched a bit
> on-line, but so far, I have not found any real solutions (but a lot of "me
> too" answers, and one suggestion to ditch the radio and make use of the
> internet...).
>
> There are what look to be ferrite beads on each end of the signal cable
> from the computer to the monitor, and on the monitor end of the power
> supply's low-voltage line (I assume it's a switching supply). There are no
> beads on the supply's power cord.
>
> All the radio equipment and the computer are using the same AC circuit.
> The rig and amp are grounded to the station ground, but the computer and
> monitor are only grounded through the AC supply.
>
> I have four clip-on ferrite beads that I've tried on each end of the
> monitor's two lines, and they make no difference.
>
> Does anyone have any suggestions? Maybe I've missed something dumb. I
> don't mind getting some big cores if necessary, but I would like to hear of
> someone's success before spending a lot of money trying to "shotgun" the
> solution, and I really don't want to get a new monitor - but if anyone has
> a suggestion of a noise-free one, please let me know.
>
> Thanks in advance. 73,
>
> Jim KO5V
> ______________________________________________________________
> 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
>

--
*N6OL*
Saying something doesn't make it true.  Belief in something doesn't make it
real. And if you have to lie to support a position, that position is not
worth supporting.
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[Jim Brown-10]

On 5/26/2019 12:15 PM, Jim KO5V wrote:
> I have a ~24" LCD monitor that I want to use for logging, to display my panadapter, etc. Unfortunately, it is very noisy on HF.

This is a very common problem. There are (at least) two heads to the
snake. The most common, and easiest to fix, is the power supply if it is
a wall wart. Wind multiple turns of the power cable through a #31
Fair-Rite core. The other head of the snake is noise from within the
monitor itself, which radiates directly from it's own wiring and from
the video cable. No fix for what radiates from it's own wiring, but
multiple turns of the video cable around a #31 Fair-Rite core will kill
that part of the noise.

Another very good solution to the power supply component of the problem
is to replace the noisy power supply with a quiet one -- namely, a
vintage linear supply with a transformer, rectifier, and filter.

There's a lot more detailed advice on this on my website.

http://k9yc.com/KillingReceiveNoise.pdf
http://k9yc.com/KillingRXNoiseVisalia.pdf

73, Jim K9YC

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[IK4EWX]

Last year I founf thet my biggest noise problem on 80m was my Samsung 21'
monitor.
Tried to solve with lot of ferrite on his external power supply and on all
cables to monitor, but I tried this kind of filtering without resolving.
Desperate, bought a new beautiful 24' NEC monitor with power supply inside.
No kind of noise on any band.
IK4EWX



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[JOE-2]

Shielded CAT cable uses special connectors to ground the shield (drain)
wire. They have a metal housing around the connector that the 9th ground
wire is connected to. This requires that the jack that the cable
connector plugs into be the appropriate type of jack that accepts the
shield ground. Without the proper jack the shielded CAT cable may not be
effective.

Joe

On 5/27/2019 7:13 AM, [hidden email] wrote:

Since going to shielded cat-5 computer wiring have few birdies on the
K3 or KX3 from the computer(s):
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