[RFI] Phone RFI fixes - no ring, lower cost solutions?
Wed, 22 Dec 1999 20:49:13 -0800
For some reason this didn't get posted...let's try it again.
> A couple more thoughts to try. The last house I lived in (abt 8 yrs
> ago) that had cable TV also had TVI problems with nothing more than 100
> watts & a dipole.
> 1. Make sure that all the cable connectors and any connectors going to
> splitters, etc., are in good shape, securely crimped onto the coax, and
> securely tightened, and that any unused splitter ports are capped. I
> fixed one TVI problem while in the process of tracking down loose
> connections by nothing more than disconnecting & re-connecting a splice
> in the cable (obviously had a poor shield connection).
> 2. Most TV's I have encountered (including both that I currently own)
> respond to relatively low-level common-mode HF signals on the antenna
> lines. An easy way to break the common mode path is to go to Radio
> Shack, buy a couple of 75 ohm - 300 ohm transformers, connect the 300
> ohm sides together, and install the pair in line with the cable coax at
> the back of your TV. Check the transformers with an ohmmeter to make
> sure there isn't a DC connection between the 75 and 300 ohm sides. This
> arrangement breaks the common-mode path while still passing the intended
> (differential mode) TV signals.
> Agree that a high-pass filter probably wouldn't do much to eliminate HF
> Gud luck & 73,
> Jon Ogden wrote:
> > on 12/21/99 7:47 PM, Gorsline Family at email@example.com wrote:
> > > Ideally, I'd like to give the neighbours the plug-in modular filters -
> > > enough for every phone (say 5/house). At $30-40 CDN each, is there a
> > > less expensive way?
> > Rich Measures, AG6K, has plans for homebrew phone filters on his website.
> > They are basically the same as what you would pay big bucks for. The URL
> > is: http://www.vcnet.com/~measures/T.RFI.html and
> > http://www.vcnet.com/~measures/phone.fil.GIF
> > Hopefully that can help.
> > >
> > > For the TVI - is there a high pass coax filter (ideally male-female to
> > > put in the CATV line)? Yes, lots of cable ingress/egress - 2m and CATV
> > > channel 18, pagers on channel 17 and 21.
> > If you are having cable ingress, contact your local cable company. They are
> > responsible for leakage into as well as out of their system. If pagers are
> > getting in then lots of people have complaints and not just your neighbors.
> > The FCC holds the cable company responsible. Realize that if you are other
> > services are getting IN, then they are radiating signal which means, the
> > CATV will likely be interfering with YOU somewhere.
> > If there is fundamental frequency ingress, filters won't help one bit. If
> > any of your VHF/UHF signals are getting into your CATV channels, then it
> > won't help to put a filter in line since your frequency and perhaps the CATV
> > channel frequency are the same. The only way to stop it is to make the
> > cable company close their system, which it should be.
> > Hope this helps.
> > 73,
> > Jon
> > KE9NA
> > --
> > -------------------------------------
> > Jon Ogden
> > KE9NA
> > http://www.qsl.net/ke9na
> > "A life lived in fear is a life half lived."
> > --
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