Question about Cable TV signals and RF Amplifiers

[softbatch]

I am preparing to run some coax cable in a family member's house. They are needing six drops throughout the house. My question is concerning RF Amplifiers.

I am concerned about the loss of signal strength as the signal is going to be split multiple times. Does anyone recommend a specific type of amplifier to boost the signal. I think I will need a 25dB amplifier to place in front of the 6-way splitter. I assume I am going to want a signal strength between 8 to 15dBmV for each TV. The farthest room is approximately 100ft from the side of the house where the main line is located.

I am fairly new to the world of CATV cabling so I may be way off on this. I was planning on running the main line to a six splitter, which would feed the six outlets. Any suggestions on amplifiers or configurations would be greatly appreciated. Thanks.

 

[jlshelton]

Besides signal gain (amplification), you will need to consider the bandwidth (range of frequencies amplified), and perhaps the noise added by the amplifier. What range of TV frequencies are you dealing with? Over-the-air VHF + UHF? Cable TV? Digital cable? Satellite?

For many applications, the inexpensive (and returnable) amps sold by Radio Shack or Best Buy would get the job done.

Are you also planning 1 six-way splitter, and home-run cabling? That sounds best. I've seen installations where the cable is daisy-chained through a house, with a splitter at each room to take off the feed for that room. Bad idea there - the last room has been through nearly a half-dozen splitters.

 

[softbatch]

The coax cable would only be carrying Cable TV signals. I was planning on having the main line feed the input on the six-splitter, and then send separate cables to each room of the house from the six-splitter. At most, I would have the six-splitter and a 2-way splitter in between the main source and the end point.

I estimated a loss of approximately 15db to the farthest room of the house. So I was planning on boosting the signal with an amplifier before it hits the 6-splitter.

Can boosting the signal too much distort the cable tv quality? In other words, should I be concerned with overkill? If so, perhaps a 15dB amplifier would be better. What do you think?

 

[bikechuck]

you will get about 8 db loss from the splitter itself. Go ahead and install it and see if it works. Then think about amps. You will probably only need it for a few drops anyway.

 

[Servamatic]

Yes overdriving your TV signal will give you poor quality.

Typically if you see a snow pattern you have too low of a signal strength.

A herringbone pattern typically means too hot of a signal.

If you have ghosting, i.e. the double image with a line down the middle...
That typically means bad splitters, connectors, or termination practices.

Richard S. Anderson, RCDD

http://www.servamatic.net

 

[wires]

Here is a cheap and easy way to check signal strength:

http://www.channelplus.com/support_tips4.html

I second the notion of go ahead with the splitters and see what happens. You may not need an amp.

 

[softbatch]

Thanks for the tips. I returned the 6-way splitter for a Leviton 3X8 splitter which has a built in amp of up to 15dB. I am actually going to run 8 drops this weekend. Hopefully everything will work, and all signals will be strong.

I noticed that the Comcast cable TV man installed a two way splitter 6 years ago when he "added" a new line to the house. The splitter was placed in a plastic box on the outside wall of the house. The plastic covering does not close so the splitter has been exposed to the elements (my city averages among the highest annual rainfall totals in the country).

So it is likely that I will need to replace that splitter and seal the box with a lock of sorts. "Half measures avail us nothing...