W8AV@aol.com wrote:
>
> I agree with Jim N4MXZ. The common mode filter that he spoke of works great.
> I used two 75 ohm to 300 ohm CATV transfromers and a 300 ohm TVI filter.
> Hook them up as follows:
>
> CATV IN - 75/300 XFMR - 300 OHM TVI FILTER - 75/300 XFMR - RCVR
>
> That should do the trick. The secret is that the filter breaks the shield so
> that the RF can not flow into the receiver on the shield of the CATV coax.
> Give it a try.
>
> 73......................de Goose W8AV
Goose,
Lets just add on thing to your design, put it in a metal box. The short
piece of 300ohm will radiate
a signal that can be picked up for a few blocks, and might violate FCC
rules and make the cable company mad. Grounding of one "F" connector
would keep the box from defeating the whole isolation concept. The cable
company should supply TVI filters at no charge, and it should be
confirmed that the cable is grounded at the entry point of the house.
This info comes from n0euh who is an old "cable rat".
Lee k0lw
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