Registered: Mar 2001
Location: Minneapolis, MN USA
Originally posted by aaronwt
The switch is grounded. The cable is the dual RG6 with a ground wire in the middle. This ground is connected to the switch and the grounding rod for the building(where the telephone and CATV are grounded) Before I had the 4 x 8 switch inside, I just used the four outputs from the switch on the dish. The interference definitely comes from the cables runnning by the main power lines. I tested this by running lines straight from the dish through a window and I didn't have any problems. I then used those cables and ran them behind the conduit for the meters outside(where the buried cable is)Once i did that I had the same interference on screen. Only when I ran it through the protected coaxial connections on the Moster Surge protector, did the interference disappear.
How did you ground your multiswitch? Where did you tie in to the building's system ground? Is the CATV system's ground rod BONDED to the building's ground bus? If it isn't grounded at the same point as your coax, you can easily get a ground loop. (I've seen CATV systems using a ground that isn't bonded to the building's main ground bus, and the same symptoms you describe have resulted.)
Typically, for most multiple dwelling buildings, the system ground is tied to the water main. (If you see a large guage wire jumpering the water meter, that is the case.) You can have other grounding points such as ground rods, but if they aren't bonded to the system ground, you almost certainly will generate a ground loop.
If the main service entrance is generating the noise, it is a 60 hz sine wave causing the problem. This is virtually impossible to filter out, and certainly a surge protector won't do it. My RG-6 is bonded to my system ground right in my service entrance panel. There is no noise whatever, and I don't run the cables through any surge limiting device whatever, even though I do have one for telephone and power lines for my system.
I'm not saying you didn't observe what you say you did. What I am strongly suggesting is that the circuitry inside your Panamax has nothing to do with curing the problem, and that you probably would observe the same result if you simply grounded the coax cable and all your equipment at any single point that is tied to the system ground. Your Panamax is grounded to your system through the grounded outlet at your wall, and in my view, that is the only reason the Panamax solves your noise problem.
What your Panamax is doing is, in effect, bonding the CATV ground rod to your system ground by way of your wall outlet. The wall outlet ground is bonded to the ground bus in your apartment's subpanel in your apartment, and that ground bus is bonded to the ground at the service entrance of the building, thereby eliminating the ground loop's effect on your TV. This scenario is symptomatic of an unbonded CATV ground rod.
I don't believe there is any way your Panamax surge protector could possibly filter out a 60 hz ground loop, and there is likewise no way the electrical service equipment could generate any other spurious signal in your coax lines but 60 hz.
"Ignore 'em, m'dear. They're beneath your dignity." W.C. Fields
Last edited by ShiningBengal on 06-27-2004 at 08:10 PM
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