Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mandrill!neoucom!wtm From: wtm@neoucom.UUCP (Bill Mayhew) Newsgroups: sci.electronics Subject: Re: connecting many TV's to my cable system Summary: Use a 17 dB tap Message-ID: <1241@neoucom.UUCP> Date: 27 May 88 13:59:38 GMT References: Organization: Northeastern Ohio Universities College of Medicine Lines: 50 When connecting a bunch of TV sets to a cable system drop into your house, first make sure that it is "legal" in your community. The cable industry is changing billing standards, and not all communities seem to have common regulations. In many areas, one now pays a flat rate no matter how many TVs are attached. Where I live, one is still expected to pay on a per set basis (yuck!). We wouldn't want you to do anything illegal :-). Anyway, now that that formality is dispensed with, to attach multiple sets to the drop into your house, you can use an item called a 17 dB tap. The taps are installed thus: (tap) (tap) (tap) (tap) cable drop----------+---------+----------+------ ... --+--terminator | | | | tv tv tv tv The 17 dB tap is a 3 port device that splits the input in either the right or left port to ~90% energy exiting the left or right port and ~10% exiting the bottom port. The terminator on the right side above can either be a 75 ohm resistor or a real load like a tv set. The system above works well because the signal level on the distribution trunk stays relatively large, being reduced by only about 10% for each tap it passes, thus all the tvs get about the same signal level. The system can also be easily extended by removing the termination and adding on more taps. Of course, if the run is long enough, a line amplifier might be necessary. There is an added advantage that the above system is relatively insensitive to the vaggaries of disconnecting one of the sets at the tap, as there is reletively little effect on impedance level reflected at the input by the disconnection. Such systems are used in hotels and appartments where joe random user might connect just about anything to the antenna terminal in his/her appartment. 17 dB taps are available at most DECENT tv supply shops (not Radio Shark, as far as I know). You might try mail order: Edlie Electronics 2700 Hempstead Pike Levittown, NY 11758 (516) 735-3330 There are, of course, lots of other places to buy such goodies. --Bill wtm@neoucom.UUCP