[RFI] Types of flatscreen (Re: Plasma TVs

[Roger (K8RI)]

On 11/11/2010 12:05 AM, John DeGood wrote:
> On 11/10/2010 4:03 PM, Jim Brown wrote:
>> I don't think I've ever heard of an LCD TV that radiated RFI trash, and
>> I don't think I've ever heard of a plasma TV that didn't produce trash.
> My experience is just the opposite.
>
> Our 42" plasma TV (older Gateway) is extremely clean.
>
> Our 37" LCD TV (newer Magnavox) renders the HF bands virtually unusable.
More than likely in this case it's the power supply. No guarantee, but 
most likely.
>   I added a Corcom filter that effectively suppressed most of the power cable RFI, but I have been unable to satisfactorily filter the 2 HDMI connections (set-top box and DVD player).  Adding 4 Radio Shack 273-104 snap-together chokes (2 on each HDMI cable) helped some but is grossly inadequate:  because of the thickness of the HDMI cable I can only fit 3 turns through eachsnap-together choke.
There are some larger cores available.  If the 3 turns does make a 
difference, check Mouser and some of the other sources . I use a lot of 
the 2.4" OD 32 mix cores for current baluns and power line chokes. The 
problem is it takes a lot of turns and cores to get the frequency down 
to the primary noise frequency.  With the HDMI lines you might have to 
stack clamp ons the full length of the cable, (which might be kinda heavy)

There are larger snapons available, but they get pretty pricey although 
they are certainly cheaper than a new TV set although even really good 
37" are now *relatively* inexpensive.

The last couple of TV sets we purchased were on a "trial basis". I 
agreed I was going to purchase a set, but that was contingent on it not 
causing RFI or being susceptible to the RF from the ham station.  I also 
had to be satisfied with the picture and sound, or overall set.  I had 
no trouble getting several stores including Best Buy to agree, but they 
were confident I was going to purchase.  I finally chose one of the 
stores due to the breadth of what they carried plus the "in store" help 
and attitudes. The first set I chose worked better than I had expected. 
OTOH it had just been announced and they only had a single 
demonstrator.  I took delivery just two days later. Of course being the 
first out, I could now purchase the newest model of that size (40") with 
the latest advances for less than 1/3rd of what I paid 3 years ago.

73

Roger (K8RI)
> 73, John NU3E
>
>
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