Need Rf Ground Breaker Design, CATV giving me 1.5v from coax

gabito · Joined: 27 Jun 2008 Posts: 2

Hi guys.. this is my first post here.

Sorry for my english. hope you can understand me.

BTW: I'm not a technician or anything.

I live in Argentina, where we still have analog CATV. The other day I measured the voltage that my cable company sends through the coax cable. To my suprise, it was 1.1v and sometimes fluctuating to 2.0v!

I guess I know now why a TV set of mine died on me last month.

Any how, I came up with a filter to get rid of the current and just let the RF signal through.

Here's my schematic:

Voltage is down to 0, of course due to the caps.

But something is wrong. We have approx 70 channels here, so:
1- channels from 2 to about 10 have very poor quality
2. channels from 20 to 30. poor.
3- 50 and up, poor.

I guess its the caps I'm using that is blocking or interfering with some of the frequencies.

Any suggestions guys?

Thanks!

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

gabito · Joined: 27 Jun 2008 Posts: 2

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

Yes I noticed that too & quite honestly don't really know why is there such a difference?
Even though I have not used the $1.99 jobs, I don't see why spend any more than have to? ---still for the little~ 2volts, it is really not necessary.

You can always try it but, remember there is always a possibility that you may notice some signal degredation with any passive device inline especially if your signal level is marginal to start with.

torbjorn · Joined: 07 Jun 2007 Posts: 370 Location: Sweden

The simplest way to achieve a such DC blocking would be to use an antenna connector with built-in blocking capacitors from any old tv with "live" chassis.

power · Joined: 11 Jul 2008 Posts: 4

Hello,

I was facing some problem with my TV. By visiting the links posted by you I have really got some help there.

Thanks for that.
_________________
http://www.powercomars.com

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

ronwelldo · Joined: 01 Jan 2009 Posts: 1

Know this is a response to an old post but...Be sure you do not bypass a ground with a filter you would be asking for damaged equipment and most certainly a poor picture. Your best bet would be to make sure the CATV is bonded electricly to the power companys ground first off. This way you would not create a difference of potential ground in your home.
Since CATV signals cover a wide frequency range within the TV/Radio frequenct spectrum and are or should be EFI/RFI shielded and is sensitive to any characteristic impedance changes within the circuit, any filter that you could make would probably not pass muster. In fact,most of the commercially available inexpensive filters present problems as well.