Hi Yuri,
A highpass filter is almost worthless for doing anything. The problem is
almost always common mode currents flowing between various wires.
Small common mode chokes like you used are also almost not worth installing.
You need many passes through a 73 mix core to have a high series impedance,
since the bypass impedance designed into the equipment is unknown.
I'd go back and put some real chokes on cores that you know the
characteristics of in the system. Maybe 10-20 turns on a large 2" 73 mix
core. The coax can be a little less, but it still needs several turns
through a high permeability core. It also helps a great deal to be sure the
coax shield is somehow bonded to the safety ground of the electrical outlet
that the TV set uses. You can normally get that connection via an outlet
wall plate center screw, or through a lightning protection outlet strip with
CATV connections, and buy a grounding block for the cable line.
By far the most effective cure would be installing an outlet strip with
built in lightning protection for cable and electrical at each TV, and
running the cable in through each strip. Be sure the strip you purchase
grounds the CATV jacks directly to the neutral of the power line. ALL
devices must power from that strip.
This will then become your "wall".
If still ineffective you should bypass all speaker leads through small
capacitors to that ground and install all chokes on the leads coming to that
point.
73, Tom W8JI
----- Original Message -----
From: "Yuri Onipko" <va3uz@rac.ca>
To: <rfi@contesting.com>
Sent: Saturday, March 06, 2004 3:52 PM
Subject: [RFI] TVI
> Hello everybody.
> My new next-door neighbor started to complain about TVI.
> I seldom use more than 100 watts from my place and
> had no other complaints from other neighbors so far including people who
> used to live
> in his house before.
> When I visited his place today I was shocked - there are 6(!) TVs in the
> house, 4 of them - flat screen TVs. Three different DVD players, CD
players
> and video (VHS) players, each connected to three of those 6 TV sets, and
one
> big flat screen TV in a basement has 5 speakers (surrounded sound) with at
> least 10' of speaker wire each and this TV set is also connected to a
> satellite receiver (the dish is on the roof) in addition to regular cable.
> All TVs are connected to the main cable line by means of 6-dB splitters.
> Wow!
> Probably good kilometer of audio, video and other wires all over the
house.
> When I point my beam (TH6DXX at 60 ') to his house (this is my Caribbean
> direction) my 100 watts signal easily wipes out his TV picture (the screen
> is flashing) on 10, 15 and 20 meters. 10 is the worse. Also my voice can
be
> heard in his speakers when I transmit on SSB. Same thing happens when I
> transmit on 80 and 160, and there was no any interference I turn my beam
> aside.
> I have no problems at all with my 2 TV's in the house connected to the
> same cable line (the distribution box for neighborhood is in my backyard)
> and to satellite RX.
> I was not really ready to do anything to cure the problem. All I managed
to
> do was to put
> High Pass filter which I put between the cable coax and TV antenna input
and
> to wind
> 3 or 4 turns of cable TV coax on the mid-sized thoroid core. Also I put
> common mode chokes (3 turns of speaker wire on thoroid) on the 3 of 5
> speakers. Nothing seemed to help.
> I suspect that his TV signal from the cable could be very weak due to the
> multiple splitters and his TV input is simply overloaded when I point my
> beam on his house. In this case - can a UHF amplifier help? Should I still
> put HPF and common mode chokes on the cable coax? Does he need AC
> "brutal-force" filter?
> I would appreciate any comment or suggestion.
> Thanks.
>
> Yuri VE3DZ
>
>
>
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>
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