[RFI] DirecTV TVI Issue

[Jim Brown]

On Tue, 21 Sep 2004 15:05:14 -0700 (PDT), Dan Levin wrote:

>Is it likely that my signal is actually getting into
>the RG-6 feed from his dish to his receiver?  It is a long
>run... If so, is the problem more likely on the shield?
>In either case, will a commercial "RFI" filter for RG-6
>(e.g. from Radio Shack) help?

I would put my first money on 

1) common mode on the RG-6

2) the TV set and connections to it

3) Pin 1 problems in a home theater setup

Both could probably be fixed with the RIGHT ferrite choke.  Consider 
this. You're clean at 100 watts but not at 1500 watts. That's roughly 12 
dB. Most RFI detection is square law, so reducing the RF level by 6 dB 
at the point where it's getting in should kill the RFI, so heroic measures 
should not be required. 

Another thought -- does he have a home theater setup? If so, you could 
be getting into that setup, so don't overlook those cables. The vast 
majority of audio and video gear has pin 1 problems. Any RF current on 
the shield will be conducted into the box. Ferrite chokes will reduce that 
current. 

Question -- what bands are most affected?  Audio or video or both?  
What about when he plays a DVD or videocassette? 


Jim Brown  K9YC