Interference free monitor

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  • Updated 3 weeks ago
  • (Edited)
I am using an Asus VG248QE 24" monitor. I've been experiencing significant interference that I thought was external to the shack. The interference repeats at ~72KHz intervals.
I pulled out an SDRPlay attached to a notebook and found the same interference, Turning off the monitor, eliminated the interference. Previously I tried removing any/all connections to my 6500 to see where the noise was coming from to no avail and by now every wire has multiple ferrites on them.
I am looking for a 24" noise free monitor, one that will not generate RF like the current monitor.
Any suggestions/recommendations?
I may also play around with the monitor-to-6500 distance but within reason there doesn't seem to be much difference. The monitor is just a great RF generator.

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Tom

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Posted 4 weeks ago

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Justin - KL2D

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Hi Tom -

I am using two Samsung U28E590 displays, no interference at all from them. They run off of 14V DC so I use the shack power supply to drive them. I know that’s a little bigger than you wanted, but they work great.

Good luck!

73
Justin
KL2D
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David Ahrendts

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Tom, I had a similar problem with a fabulous LG monitor and my Flex 6500. Changed it out with Samsung gaming monitor and stepped up RF shielding. The LG required an unusual 24V DC, where the Samsung needed 12V which allowed me to dump the LG switching power supply wall-wart (the likely cause of the inference) and replace it with a high end 12V non-switching power supply which was routed through a shielded and filtered West Mountain Radio distribution box. And one more thing, use sheilded twisted pair wire to run power to the monitor. All these steps bring the noise from the monitor to nothing. I run two Samsung's within 2-3 feet of the Flex-6500. Totally quiet.  

David A., KK6DA, Los Angeles
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Neal - K3NC, Elmer

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How is your monitor connected to your computer? 
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Steven G1XOW

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That noise is most likely coming from the SMPS inside the monitor.

5 turns on a large ferrite ring at both ends of the video cable, and importantly the same again on the power cable directly before it enters the monitor will crack most of this.

Also ground the monitors to station ground. Route your RF cables and video/power cables well away from each other.

Additionally, I also route all my mains power/monitor/computer/video cables inside 6 feet of copper pipe which is bonded to station ground.


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Tom

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Thanks for all the comments.
The monitor is connected via an HDMI cable to the computer. I have a mix 31 snap on ferrite with an overlapping loop at entrance to monitor followed by a non descript smaller ferrite on the cable just below the loop and another mix 31 snap on where the HDMI cable enters the computer.
The power is direct to AC, no wall wart. I have a mix 31 snap on at monitor followed by smaller snap on as on the HDMI cable. Will try getting larger toroid and 5 turns per Steve.
No station ground on monitor yet - only gear w/o one, will have to find a piece of metal then hook one up.

More experiments to do but it probably is the internal SMPS causing the issue.  Other issue may be proximity of monitor to 6500 (now less than 12"). Coax already moved away a bit.

Hmmm...maybe a heathy gold flash around the whole thing would help!!

Lastly, I like the idea of a monitor working off the station 12V bus.

Thanks all..
Tom W4IEE
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David Ahrendts

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I'd swap out the monitor for another. Bet you'll see a huge difference. And yes, a single 12V bus, heavily filtered and generous use of ferrets always helps. Keeping A/V cables separate from RF cables good too. Its the monitor.
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Tom

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An update

The monitor is not the problem! Not sure what is the problem yet but I'll get to the bottom of it shortly. I did swap out the monitor, swapped out station PS, added another batch of ferrites everywhere to no avail. Even disconnected an inverter on my golf cart! Nothing yet.
Will be putting my SDRPlay to work to track down the culprit.
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Tom

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Final - Went around my house with an SDRPlay and an 8' dipole I  made up out of plywood. Nothing! Finally I did what I should have done in the first place - switched off breakers. One GFCI breaker when off killed the noise. I use an SGC230 remote tuner for a long wire (HOA) and was providing 12VDC via a wall wart. That was the problem. A couple of 4" dia mix 31 ferrite toroids on input an output, aluminum foild around the wart and a TripLite -100db suppressor/surge box did the trick. The problem was mostly the Ac side. Now to go back and take stuff off to find out where the problem can be corrected with minimal ferrites.
Solved! Quiet shack at last.
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Ted VE3TRQ

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Easiest (and quietest) way to supply power to an SGC230 is a bias-t, feeding 12v thru the coax. I chose to run a separate control cable from the shack to provide 12v plus control to the SGC230 and status from it. Have I said lately how much I hate wall-warts? :-) I use the shack supply for as much as I can, including monitors and computers.
(Edited)
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Tom

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I agree Ted. Actually my fix will be short lived. I am getting an Elecraft 500 w amp after the new year and Santa is giving me an MFJ 998 RT with a Bias T included. But, alas, I learned how to ID and fix the issues so I will be ready for a future adventure!
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Ted VE3TRQ

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Merry Christmas, Tom, and enjoy that KPA500. The only HF radios I own are American-made - a K3, KX3, and a Flex. I hope to add a KPA500 when I get an outdoor antenna up (HOA rules make it hard).
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Ernest - W4EG

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Ted,
Climb the northern border fence and we will welcome you aboard! LOL
As you may know the USA deny our number 1 nemesis in the Congress this last year election; and hopefully the new member of Congress will go along with the Parity Act (H.R. 555) of last year 2017/18.
That should remedy HOA CC&R here in the USA. 
Hope that your Canadiens amateurs get together and pass a similar act.