eHam

eHam Forums => Elmers => Topic started by: W4FBI on March 13, 2013, 01:31:32 PM



Title: Computer Monitor RF Interference
Post by: W4FBI on March 13, 2013, 01:31:32 PM
I have read several posts on the subject - but few "results" posted.

I have a fairly new LCD (not LED) Samsung flat screen for my computer monitor. I get some  interference at 20 meters and higher. When I turn it off - bingo, perfect reception!

My computer is grounded to earth ground - but that made no difference. It's the monitor and/or it's associated cables.

Surely others have solved this (ferrites?) Appreciate any suggestions

Alan, W7EJT
Myrtle Beach, SC



Title: RE: Computer Monitor RF Interference
Post by: W5CPT on March 13, 2013, 01:46:25 PM
Is the power supply for the monitor built in or is it a wall wart?  If it is a WW, it may be a switching type which are often very noisy.  If so, it should be fairly easy to find an analog supply and replace it. If not I would try the ferrites on the power cable since if it were the signal cable the interference would continue when the monitor is turned off.

Clint - W5CPT -


Title: RE: Computer Monitor RF Interference
Post by: K0YQ on March 13, 2013, 02:37:34 PM
Did you try changing the monitor's refresh rate?


Title: RE: Computer Monitor RF Interference
Post by: W8JX on March 13, 2013, 02:48:00 PM
I have read several posts on the subject - but few "results" posted.

I have a fairly new LCD (not LED) Samsung flat screen for my computer monitor. I get some  interference at 20 meters and higher. When I turn it off - bingo, perfect reception!

My computer is grounded to earth ground - but that made no difference. It's the monitor and/or it's associated cables.

Surely others have solved this (ferrites?) Appreciate any suggestions

Alan, W7EJT
Myrtle Beach, SC

First of all, all flat panel monitors have a LCD display, a LED one means it has a LED back light behind LCD screen. Those lacking LED back light use a type of florescent light source than can create RFI. It could be light or power supply for it. Ferrite beads would be first step here.     


Title: RE: Computer Monitor RF Interference
Post by: WA3SKN on March 14, 2013, 04:46:24 AM
You have an interference issue.
The answers are distance (from source to antenna), shielding, and filtering.
Getting the source and pickup point as far apart as practical, shielding between the source and pickup point, and filtering to keep the source from radiating a signal.
Any combination that works will be fine.
Good luck with the project!
73s.

-Mike.


Title: RE: Computer Monitor RF Interference
Post by: W4FBI on March 18, 2013, 02:32:13 PM
OK, thanks for the tips!

My monitor is not LED backlit (wish is was) Anyhow, my video from the computer is transported via an HDMI cable. I just noticed NO Ferrites on this cable!. I have one on order with two ferrites. Hoping that will fix it.

BTW, the monitor is actually a Samsung 23" 1080P LCD Television, but has plenty of different inputs (including PC). I may try standard VGA cable (with ferrites) if the HDMI doesn't work out.

thanks, again...  ;D


Title: RE: Computer Monitor RF Interference
Post by: N4NYY on March 18, 2013, 02:38:24 PM
How far is the antenna as someone asked? I have a laptop, Sansui 19" LED backlit TV, and a 42" Samsung Flourescent LCD TV, all with 4 feet of my rig. Not a hint of RF.


Title: RE: Computer Monitor RF Interference
Post by: WA3SKN on March 19, 2013, 11:46:03 AM
Do you lose the interference when the cable is not connected?  If yes, it is probably not incoming via the cable.

-Mike.


Title: RE: Computer Monitor RF Interference
Post by: W4FBI on March 20, 2013, 03:29:44 PM
Do you lose the interference when the cable is not connected?  If yes, it is probably not incoming via the cable.

-Mike.

Mike, Great tip! I haven't tried that one. I just turned off the monitor and the interference goes away. That's next on my list... thx again!