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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Interference



 
 
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  #1  
Old August 27th 15, 09:19 AM posted to uk.tech.digital-tv
Brian-Gaff
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Posts: 576
Default Interference

I noticed the other day that one cannot use a portable DAB if a friends
laptop is on charge. On fiddling with my scanner I notice that this power
supply chucks out so much broadband hash, weak fm stations are clobbered,
indeed its got birdies and wandering warbling noises from long wave all the
way up to about 300 megs.

Not unusual unfortunately.
Why do these manufacturers not put in some suppression of all this? I
wonder if its bad design, cost saving or they just don't care if the stuff
coming out is the right voltage.

Brian

--
From the Sofa of Brian Gaff Reply address is active


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  #2  
Old August 27th 15, 09:26 AM posted to uk.tech.digital-tv
Deanna Earley
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Posts: 10
Default Interference

On 27/08/2015 10:19, Brian-Gaff wrote:
Why do these manufacturers not put in some suppression of all this? I
wonder if its bad design, cost saving or they just don't care if the stuff
coming out is the right voltage.


All the above. The latter exasperated by "not my problem".
Is it an official one, and which manufacturer?

--
Deanna Earley , )

(Replies direct to my email address will be printed, shredded then fed
to the rats. Please reply to the group.)
  #3  
Old August 27th 15, 09:37 AM posted to uk.tech.digital-tv
Tim+[_2_]
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Posts: 83
Default Interference

"Brian-Gaff" wrote:
I noticed the other day that one cannot use a portable DAB if a friends
laptop is on charge. On fiddling with my scanner I notice that this power
supply chucks out so much broadband hash, weak fm stations are clobbered,
indeed its got birdies and wandering warbling noises from long wave all the
way up to about 300 megs.

Not unusual unfortunately.
Why do these manufacturers not put in some suppression of all this? I
wonder if its bad design, cost saving or they just don't care if the stuff
coming out is the right voltage.

Brian



Was it an original charger or an aftermarket one? There are some very
shoddy & dangerous ones around.

Tim
  #4  
Old August 27th 15, 12:52 PM posted to uk.tech.digital-tv
Woody[_5_]
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Posts: 1,865
Default Interference


"Tim+" wrote in message
...
"Brian-Gaff" wrote:
I noticed the other day that one cannot use a portable DAB if a
friends
laptop is on charge. On fiddling with my scanner I notice that
this power
supply chucks out so much broadband hash, weak fm stations are
clobbered,
indeed its got birdies and wandering warbling noises from long wave
all the
way up to about 300 megs.

Not unusual unfortunately.
Why do these manufacturers not put in some suppression of all
this? I
wonder if its bad design, cost saving or they just don't care if
the stuff
coming out is the right voltage.

Brian



Was it an original charger or an aftermarket one? There are some
very
shoddy & dangerous ones around.


I have used HP (Compaq,) Dell, and Lenovo and they ALL do it, Dell
being one of the worst.


--
Woody

harrogate3 at ntlworld dot com


  #5  
Old August 27th 15, 01:55 PM posted to uk.tech.digital-tv
NY
external usenet poster
 
Posts: 1,329
Default Interference

"Brian-Gaff" wrote in message
...
I noticed the other day that one cannot use a portable DAB if a friends
laptop is on charge. On fiddling with my scanner I notice that this power
supply chucks out so much broadband hash, weak fm stations are clobbered,
indeed its got birdies and wandering warbling noises from long wave all
the way up to about 300 megs.

Not unusual unfortunately.
Why do these manufacturers not put in some suppression of all this? I
wonder if its bad design, cost saving or they just don't care if the stuff
coming out is the right voltage.


FM reception (on a long trailing wire type aerial, as supplied with the
radio!!!!) in one of our bedrooms is very poor. Everywhere else in the house
is fine. It is worst near a wall with our neighbours, so I dread to think
what equipment he has in his bedroom. I've tried with all PCs,
laptops/chargers and USB phone chargers in the vicinity turned off, so that
just leaves things that are out of our control. I even turned off all the
mains to the house and fed the radio from a 12V-mains converter from the
car, just to check thoroughly!

However in/near our Homeplug Ethernet-over-mains devices, FM reception is
perfect, which is reassuring.

My parents have great problems getting FM or DAB reception near a desktop
PC, and you'd think that whatever is going on inside a PC, an earthed metal
box would not let much out. And it is the PC: even with keyboard, mouse,
monitor etc disconnected, the FM hash is still the same. I even tried a
different (internal) PSU in case...

  #6  
Old August 27th 15, 02:13 PM posted to uk.tech.digital-tv
Dave Farrance
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Posts: 1,551
Default Interference

"Brian-Gaff" wrote:

I noticed the other day that one cannot use a portable DAB if a friends
laptop is on charge. ...


It's usually the older generation of LCD monitors with CCFL backlights,
and the ballasts wreak RFI havoc on everything. Same applies with that
generation of TVs.
  #7  
Old August 27th 15, 02:24 PM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
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Posts: 4,326
Default Interference

In article , NY
wrote:
My parents have great problems getting FM or DAB reception near a
desktop PC, and you'd think that whatever is going on inside a PC, an
earthed metal box would not let much out. And it is the PC: even with
keyboard, mouse, monitor etc disconnected, the FM hash is still the
same. I even tried a different (internal) PSU in case...


As per another thread, 'earthed' may not mean much here since once a box is
ona lead much longer than a wavelength or so from the real ground, it isn't
being clamped down in potential at RF.

However if the case is metal and had no openings it should act as a cage.

Have you tried a filter and/or ferrite block on the mains lead or other
leads? The leads may act as 'openings' to let out the hash.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

  #8  
Old August 27th 15, 07:02 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default Interference

NY wrote:

My parents have great problems getting FM or DAB reception near a
desktop PC, and you'd think that whatever is going on inside a PC, an
earthed metal box would not let much out.


Metal cases leak signal like made at the seams.

Bill
  #9  
Old August 27th 15, 07:05 PM posted to uk.tech.digital-tv
Brian-Gaff
external usenet poster
 
Posts: 576
Default Interference

Its a chinese Dell replacement as the original one had the low voltage end
go up in flames due to excessive wiggling or whatever.


Brian

--
From the Sofa of Brian Gaff Reply address is active
"Deanna Earley" wrote in message
...
On 27/08/2015 10:19, Brian-Gaff wrote:
Why do these manufacturers not put in some suppression of all this? I
wonder if its bad design, cost saving or they just don't care if the
stuff
coming out is the right voltage.


All the above. The latter exasperated by "not my problem".
Is it an official one, and which manufacturer?

--
Deanna Earley , )

(Replies direct to my email address will be printed, shredded then fed
to the rats. Please reply to the group.)



  #10  
Old August 27th 15, 07:09 PM posted to uk.tech.digital-tv
Brian-Gaff
external usenet poster
 
Posts: 576
Default Interference

I have a Dell here and its quite quiet.
However, my neighbours daughter has I think a Lenovo or whatever its
spelled like and that puts out a weird crackling noicse, even in the air
band through the wall ont my scanner aerial on the roof.

I've been told a lot of it is saturation of the transformer making all
waveforms have sharp edges.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Woody" wrote in message
...

"Tim+" wrote in message
...
"Brian-Gaff" wrote:
I noticed the other day that one cannot use a portable DAB if a friends
laptop is on charge. On fiddling with my scanner I notice that this
power
supply chucks out so much broadband hash, weak fm stations are
clobbered,
indeed its got birdies and wandering warbling noises from long wave all
the
way up to about 300 megs.

Not unusual unfortunately.
Why do these manufacturers not put in some suppression of all this? I
wonder if its bad design, cost saving or they just don't care if the
stuff
coming out is the right voltage.

Brian



Was it an original charger or an aftermarket one? There are some very
shoddy & dangerous ones around.


I have used HP (Compaq,) Dell, and Lenovo and they ALL do it, Dell being
one of the worst.


--
Woody

harrogate3 at ntlworld dot com



 




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