[RFI] TVI

[Doug Grant]

> Here is the problem. TV on second floor. Tower is about 5 feet away, on the 
> other side of the wall. I have had TVI issues with this TV (Sylvania 32 inch 
> color) on HF but have tamed it with toroids on the cable lead in and the power 
> cord. Even with the KW.
> 
> On 50 mhz, with my 5 element yagi 30-50 feet above the TV, and the roof, 
> depending on how high I have it cranked up, I take the TV sound (primary) and 
> picture (not so critical) out with 2 watts. This happens when the antenna is 
> pointed directly over the house. When the antenna is at right angles to the house, 
> no TVI, even with 100 watts. This is on all channels and with cable TV. I have 
> had new cable run, quad shield, with no improvement.
> 
> I have added all kinds of toroids to both AC line and the cable with only 
> slight improvement. There is a seamless aluminum rain gutter, 30 feet long, 
> running along the roof a few feet above the TV. In the same direction as the TVI. 
> Grounding it has not helped. 

While we have all discovered common-mode ingress (which is what toroids on line cords and cable fix), don't forget good ole differential-mode ingress. Insert even a dumb old Radio Shack High-pass filter in-line with the coax. Just fixed my own TVI at my new vacation house that way.

Radio Shack does not appear to carry such filters nowadays (I had a few old ones left over), but cable TV shops like Coast CATV Equipment Supply, Inc. in Corona, CA 92880 Tel: (800) 800-2770  appear to carry suitable filters. Check out http://www.coastcatvsupply.com/Pico/picomacom.htm

GL and 73,

Doug K1DG