QRM - Interference to Short Wave (HF) Radio Pt2

Source now confirmed as aPanasonic Plasma TV in a house 200-300 meters from radio receiver's antenna (outside HF dipole). OfCom (UK) investigated problem, but said it wasn't emitting enough interference (going by their guide rules) to continue their investigation, even though it was radiating on the Air Sea Rescue frequency 5.680 Mhz... amonst 100's of others. They did say however, that there is a growing file on these type of problems! The investigators were really nice blokes but it was out of their control.

Category:

Science & Technology

Tags:

• Interference
• QRM
• Panasonic Plasma tv
• PLA
• PLT
• BT Vision
• HF
• Short Wave Reception
• Adapters
• Adaptors
• Ethernet
• Power line
• UKQRM Ofcom

[bloodwynpig7]

As I said..the QRM is coming out of the front of the TV ....NOT... wires or power supply. You have to get a special glass screen with a mesh embeded in glass. This can be done with the factory customer services being involved. No amount off messing with wires or filter will cure this interference...the problem is radiated from the front of the TV screen. It is a well known problem at OFCOM by the way!

[piji60]

hello,

A Samsung technician was at home Saturday... Very surprised and disappointed to check the QRM. He left me an AC filter (teac one from panasonic TV). I conected it today, but without any effect.

It's a real mess, coming by the electric cables. I put Tores everywhere but nothing works...

73

[bloodwynpig7]

Once again...the QRM from most Plasma TV sets radiates from the screen. There is nothing that can be done unless the manufacturer changes the screen (for a fine mesh filter screen) or you buy another model and risk the same problem. Panasonic changed my screen and it reduced the QRM significantly. NO Amount of mains filtering will clear the QRM because..it is not on the mains.

[piji60]

Hi,

I have the same problem with my Samsung Plasma TV...

QRM is circulating through electric wires in the whole house...

Do you know if a solution exists to fix this bad issue ?

73

[bloodwynpig7]

With discreet discussions, with a certain customer service department, and a very helpful neighbour, the problem was reduced by around 75%. The noise is radiated from the FRONT of the set. The only solution is to replace the glass/screen with anl RF reducing one, which has a special mesh imbedded.

It is always a good idea to make sure that leads EXITing the TV, have RF chokes attached. Don't forget and coax leads that run out to external ariels also.

[bloodwynpig7]

I forgot to mention, the customer service department I refer to is the manufacturer not the retailer (who will have very little understanding of this problem).

[Meduzi]

Ofcom are toothless nowadays. Of no use whatsoever.

[ciucciofrullo]

@bloodwynpig7 : There are three effective solutions that surgically will remove that noise forever.

WiMo QRM Eliminator, MFJ 1026 Noise Canceller, TimeWave ANC-4, all derived from the originally manufacured S.E.M. QRM Eliminator (Isle of Man UK).

They superimpose the noise captured from a pick-Up antenna rotated by 180° to the original antenna signal and wipe it out compketely.

I use it daily and my life got really better !!

Bob

[DataID]

Have you checked your switching power supply? Try it again with a clean 12V battery...I had the same problem with a cheap PS made in China!

[HurricaneSondra]

then you need to either get a differant tv set, or have the supply filtered down using band pass wilters on both sides. the side of the supply where the current comes through,m and on the tv screen/display panel to BLOCK most of that qrm. just giving advice.

[ZeroFossilFuel]

I just traced the source of my own steady S9 QRM on 80 and 40m to the 3.3v supply of my Buffalo WHR-G54S wireless router. Hoping I can quench it at the source using split RFI ferrites. Really annoying! >:-(