We went over this in a post a couple of months ago.
A typical DBS LNB will output -35dBm (digital signals are traditionally measured in dBm v/s dBmv).
A typical receiver requires greater than -55dBm to operate properly. Some will go lower. The loss of RG6 in a DBS system is roughly 8dB per 100 feet. To make it simple, we'll make it 10 dB/100 ft.
55 - 35 = 20. You need -55, you start with -35. At 10 dB per hundred feet, you have 200 feet to work with.
I know, I know, "but my brother-in-law installed a system using 14,000 feet of cable and it worked just fine!" I've heard it before.
There are any number of different types of multi-switches, some are active, some are passive, some are something in between. The better ones will lose about 10 dB through the internal splitter, but will have a 10 dB gain amplifier built in to compensate for it. It gives an effective 0/0 loss, making it irrelevant.
It sounds to me like you're starting out with too much loss, and it's being compunded by a loss through the multi-switch. Chances are, your antenna (that's dish for those that don't know) is not properly aligned to begin with, and it's complicating things.
A "peaking" meter is just that: Used to measure peak signal level without giving an exact measurement, and they will get people in trouble. "But my whiz-bang top-of-the-line gizmo that I got from (insert distributor name here) says everthing's hunky dory". I've heard that before also.
In the end, you have an improperly-installed system, with a bunch of moving parts thrown in the mix making things worse.
"Too much cable" is anything over 200 feet.
By the way, when I was doing the SBCA certifications, I always used the term "skew" rather than "tilt" to describe alignment. Keeps the two terms from bumping into each other.
Re: how much is to much cable in a dtv system
Member #: 36232
Registered: 2/16/2005
Posted:
218
Name:
Rob
Occupation:
Engineer
Location:
Sunny Florida
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