Hi Alan
Thanks for your interest and commiserations.
On 13/10/2012 19:24, Alan Melia wrote:
Hi Eddie my commisserations on you interference, but can I refer you
to the regulations and in particular the "conditions of your (TV)
licence" "You must not cause undue interference to any other radio
television reception with your TV eqipment"
Note it does not say "broadcast".
Yes but I think that the interference report form does not cover Amateur
Radio and it is an unprotected service although Ofcom does deal with
cases of interference due to faults.
It is interesting you have interference at 500kHz but not 472kHz. This
almost suggests an older CRT system with 15.625kHz line scan coils.
Plasma interference is usualy from one of the PSUs and is radiated by
the braid of the aerial. A TV braid breaker will often cure this.
No way is this older CRT stuff, I know of 3 Panasonic Plasma TV's
locally and get interference from them all the worse one, (closest) is
through the lounge wall. Whereas the PSU' may radiate via the mains lead
or antenna feeder Panasonic are well aware of that and have gone to
great lengths with huge chunks of ferrite. The main radiation from
Plasma TV's is directly via the screen, the plasma discharge, and
spreads from LF to UHF, scan rates probably give rise to concentrated
bands of interference which can be noticed when tuning the bands or a
short wave portable RX, I assume this provides the 472KHz dip. It is
really bad at 136 KHz see this picture from my gallery of filth.
http://i221.photobucket.com/albums/dd243/radiotalk/zjo_grab600.jpg
I did try braid breakers on the main offender, mains and antenna feeder,
there was no change what so ever.
The interference in the SW BC Bands is also imposed on my telephone line
and those in the street right up to the nearest BT cabinet.
Unfortunately BC stations can still be heard on a SW 'tranny' providing
you are not too close to the source TV, within 10ft through a brick
wall, so I cant claim BC interference.
If you are on good terms with your neighbour it might be worth drawing
their attention to the licence conditions, and suggest they contact
their supplier, as you may have to make a complaint. The supplier
might be more "sensitive" than the neighbour, you may then suggest a
"cure" to try. The RSGB did used to stock these filters which are
normally used for VHF but are very effective for SMPSU radiation.
I am on good terms with them, I told them in good humor when they put
their house on the market that I would be so pleased to see the back
them with their Panasonic, unfortunately the recession meant there were
no buyers. Still the new buyers could have 2 or 3 Panasonic's aye.
I contacted Panasonic on their behalf, to be fair they offered to
investigate, however, I know that the set is no worse than any other
example of the same model. In that case any call out would be chargeable
and futile, a fact which they agreed.
It does work and these problems can be cured.
Panasonic Plasma problems are know worldwide they are the worst
offenders among all the plasma bad technology. The only cure which my
neighbor will not accept is a lead box around all 6 sides including the
screen. The final 'cure' will be failure in time although prior to that
I understand the QRM will get worse as the set ages, thankfully it is
old technology and there is very little likelihood of a replacement
being Plasma
73 Eddie
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