cable TV interference - Audio only - no picture change

[Jim Bradley]

Ok here is the deal. At my brother house we have installed a base set
up. We have a mobile radio hooked up to an antron 99. The antron is in
the attic on the 3rd floor of the house mounted in a 22ft tall section
of the attic. The SWR is below 1.5 on all channels. everything is
stock. only one TV in the house is getting audio only interference
nothing else is getting any interference. This is clear as day when
ever you TX.

This happens with the TV muted or unmuted for that matter and even with
the coax unplugged from the back of the TV.

I just bought a B&W TVI filter off ebay in hopes that it might help. Do
you think it will? What else can we do? Please help...

thanks
Jim

[Vinnie S.]

On 9 Jan 2006 15:12:53 -0800, "Jim Bradley" > wrote:

>Ok here is the deal. At my brother house we have installed a base set
>up. We have a mobile radio hooked up to an antron 99. The antron is in
>the attic on the 3rd floor of the house mounted in a 22ft tall section
>of the attic. The SWR is below 1.5 on all channels. everything is
>stock. only one TV in the house is getting audio only interference
>nothing else is getting any interference. This is clear as day when
>ever you TX.


Jim,

Make sure you are using Belden 9913, or LMR400 coax, or some other 100% shieled
coax,

>This happens with the TV muted or unmuted for that matter and even with
>the coax unplugged from the back of the TV.

Well, I hate to say this, but the modern day TV receivers are junk, and pick up
anything. The TV might be the problem.


>I just bought a B&W TVI filter off ebay in hopes that it might help. Do
>you think it will? What else can we do? Please help...

50-50

Vinnie S.

[Vinnie S.]

On Mon, 09 Jan 2006 19:04:24 -0500, Vinnie S. > wrote:

>On 9 Jan 2006 15:12:53 -0800, "Jim Bradley" > wrote:
>
>>Ok here is the deal. At my brother house we have installed a base set
>>up. We have a mobile radio hooked up to an antron 99. The antron is in
>>the attic on the 3rd floor of the house mounted in a 22ft tall section
>>of the attic. The SWR is below 1.5 on all channels. everything is
>>stock. only one TV in the house is getting audio only interference
>>nothing else is getting any interference. This is clear as day when
>>ever you TX.
>
>
>Jim,


I forgot to mention the A-99 is notorius for TVI. You might be better off doing
the 1/2 vertical dipole, and doing the RF choke balun Scott mentioned.

Vinnie S.

[Jim Bradley]

do you think getting the antenna outside and further away from the TV
would help. the base of the antron is really only like 10 feet from the
TV if you were to trave straight up. the mobile in my car does not
effect it.

[Jim Bradley]

do you think getting the antenna outside and further away from the TV
would help. the base of the antron is really only like 10 feet from the
TV if you were to trave straight up. the mobile in my car does not
effect it.

[jim]

Jim Bradley wrote:

> do you think getting the antenna outside and further away from the TV
> would help. the base of the antron is really only like 10 feet from the
> TV if you were to trave straight up. the mobile in my car does not
> effect it.
>
swap the tv that has tvi with one that doesn't and see if the problem
persists. that will guide you in the right direction.

[Vinnie S.]

On 9 Jan 2006 18:01:11 -0800, "Jim Bradley" > wrote:

>do you think getting the antenna outside and further away from the TV
>would help. the base of the antron is really only like 10 feet from the
>TV if you were to trave straight up. the mobile in my car does not
>effect it.


I have heard that the A-99 is bad for TVI. I think it's too close. Try what Jim
said. Then is that don't work, try using a horizontal dipole at the very top of
the attic.. Get is as far away as possibly.

Vinnie S.

[Jim Hampton]

"Jim Bradley" > wrote in message
oups.com...
> Ok here is the deal. At my brother house we have installed a base set
> up. We have a mobile radio hooked up to an antron 99. The antron is in
> the attic on the 3rd floor of the house mounted in a 22ft tall section
> of the attic. The SWR is below 1.5 on all channels. everything is
> stock. only one TV in the house is getting audio only interference
> nothing else is getting any interference. This is clear as day when
> ever you TX.
>
> This happens with the TV muted or unmuted for that matter and even with
> the coax unplugged from the back of the TV.
>
> I just bought a B&W TVI filter off ebay in hopes that it might help. Do
> you think it will? What else can we do? Please help...
>
> thanks
> Jim
>

Hello, Jim

There is enough rf getting into that unshielded television for the audio
section to detect and amplify it. Since removing the coax from the tv does
not change the problem, no filter on the transmitter is going to help. Your
SWR won't affect it.

If you have external speakers, I suspect that rf is being picked up by the
speaker leads and conducted back to the television where the audio section
is getting enough rf to detect and amplify it.

You might try a choke on the speaker leads near the television and see if
that helps. Before you try that, try disconnecting the external speakers
(if, indeed, you have them) and see if you get any interference running only
on the internal speaker (I'll bet you don't). If you don't, you'll know
that the interference is being picked up by the speaker leads. Should that
be the problem, see if you can substantially shorten the speaker leads as
they will become much less efficient at picking up rf.

Good luck; with the cheap stuff being made, you may need it.


73 from Rochester, NY
Jim

[Scott in Baltimore]

You may have one of those sets that was built with absolutely
no filtering in it. I bet it's leaking IF around 45 MHz.

[I AmnotGeorgeBush]

From: (Vinnie*S.)
>Well, I hate to say this, but the modern day TV
>receivers are junk, and pick up anything.

>Vinnie S.

I'll take your word for it. I thought most were just poorly installed
and could be better (shielding, grounding, protectors, GFIs). I know
that it's very easy for an average station in very close proximity with
other homes to come across a neighbor's surround sound or pc speakers.

[I AmnotGeorgeBush]

From: (Jim*Bradley)
>do you think getting the antenna outside and

>further away from the TV would help.


Absolutely. The further (and higher) the better.

>the base of the antron is really only like 10 feet
>from the TV if you were to trave straight up.

Way too close.

>the mobile in my car does not effect it.

Get it up and away.