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  • From: Mark Turner <markt AT siteseers.net>
  • To: "Internetworkers: http://www.ibiblio.org/internetworkers/" <internetworkers AT lists.ibiblio.org>
  • Subject: Re: [internetworkers] CATV signals
  • Date: Mon, 19 Dec 2005 22:31:52 -0500

Tom Caswell wrote:
I have a CATV setup and a problem. The signal seems to degrade as the
channels get higher. It's pretty grainy around Food Network which we watch
alot.
Here's my setup:
Wall -> Surge Protector -> Splitter -> TV and Tivo.
I split the signal because I want to be able to watch something else if the Tivo is recording a show. I've tried inserting a Radio Shack CATV amplifier into the setup according to instructions. The TV becomes unwatchable. Was the signal too high or did I possibly install it incorrectly? The signal is very clean if I go straight from the wall into the TV.

Everytime you add a connector to the line, you lose at least 3db of signal, which is significant. Minimize the number of things you put between the source and your TV. For instance, you can dispense with the surge protector, which does more harm than good as it offers signal loss (remember the 3db?) and essentially worthless protection.

An amplifier will amplify everything it receives. Thus you want to give it more signal and less noise. Always place it as close to the source as possible (i.e. wall, antenna, etc.) so that it is amplifying what you want it to amplify.

As Tony and Scott pointed out, not all splitters are alike. A 1000 MHz one is the baseline for today's cable services. Your amp should also be 1000 MHz as well. (For the record, gold contacts are a waste of money).

Last but certainly not least is the quality of your cable (or feedline, if you're a ham/AV geek like me). The higher the frequencies, the more signal leaks out through the cabling. In the past, RG-58 or RG-58 cable was adequate for most jobs. Now you should use RG-6 for just about everything, as its level of shielding works best for the high frequencies. The cable will have the RG level stamped along the side.

Happy viewing!

Mark (N4JMT)

Mark Turner
www.markturner.net




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