[RFI] Digital TV Problems

[DGB]

I have a tribander up about 55 ft. and about 95 ft. from the troublesome TV.

The phone company claims they have a filter at the entry to the house, 
what the name of these different boxes are, I have no clue. Do know that 
a cable runs from there to a box that one of the serviceman called a 
coax converter. From there it seems there is a cat45 cable going to the 
Internet modem and wireless router for the computers of the qth. Also 
from there is another cable going to a splitter with cable that lead off 
to the various tvs. At each of the tvs there are two boxes, again what 
those are I don't know.

Also don't know if the ferrites are of the correct mix, just a bunch of 
misc. ones I've acquired in the past. Some of them are the Radio Shack 
clamp-ons.

thanks 73 Dwight NS9I

dgsvetan at rockwellcollins.com wrote:
> Dwight,
>
> An interesting problem, especially since I heard recently that some 
> community CATV systems are planning to run digital video on CAT-5 lines 
> around town.  That's a truly scary thought.  I have heard of one system in 
> another town that is working, but they did use SHIELDED CAT-5E cable 
> (verified by visual inspection by hams).  In your case, a few questions 
> come to mind:
>
> 1.  What is the orientation of this one problem set  relative to your 
> antennas?
>
> 2.  What is the connecting device between the TV and the phone lines?  Is 
> it a passive balun or an active device "converter" box?
>
> I saw K9YC's reply to your inquiry.  Read and heed the info from his web 
> site.  The grounds you have are very nice and good for system protection 
> from lightning damage, but this is strictly an RF overload problem 
> somewhere.  If the TV was good on an outside antenna before, it is 
> probably not the set that is the problem now.  You should concentrate your 
> efforts on the interface between the TV and phone lines, and don't forget 
> that if you use ferrites, be sure they are appropriate for the frequency 
> bands you are using. 
>
> Please keep us informed on your progress, and best luck.
>
> 73, Dale
> WA9ENA
>
>  
>
>
>
> DGB <blueheron at Bayland.net> 
> Sent by: rfi-bounces at contesting.com
> 03/31/2008 07:18 PM
>
> To
> rfi at contesting.com
> cc
>
> Subject
> [RFI] Digital TV Problems
>
>
>
>
>
>
> I've recently had  subscribed to a service thru the fone lines that 
> include TV and Internet. I've had the internet thru it for a long time.
>
> I have 4 tv's in the house hooked to this system.
>
> My shack is in a separate building but still about 30' from that problem 
> tv. I've a good single point grounding system that is all connected to 
> the tower, the service here in the shack, and the house's service. It's 
> all connected undergnd with 2" copper and gnd rods every 16' (over 30 
> rods).
>
> Recently I've been getting into the TV when xmtg but just one of the 
> tv's. My signal scrambles the digital image, like tiling.
>
>  I never had that problem when the tv had an outside antenna, even when 
> running legal limit. I've put several clamps-ons on the problem tv. I 
> also have a cat5 and telephone cable coming out here to the shak 
> underground and have clamp-ons on them as well.
>
> Where do I start?
>
> Thanks ... 73 Dwight NS9I
>
>
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