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  #1  
Old April 30th 04, 06:22 PM
J. Sun
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Default ground loop

Is it ground loop problem ?
I have a outdoor ant fed into my tuner tu-9900 then ARC ls-3 (known
for being sensitive to ground loop). There is noticeable humming no
matter I play tuner or other source but disappears if I disconnect the
ant input. I did ground the antenna using a grounding block, the
problem is improved but still there.
Any help/comment is appreciated ! Thans!
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  #2  
Old May 1st 04, 01:29 AM
MIKE
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Default ground loop

Do you have a cable TV connection? These are known to cause ground
loops. There are isolators available to correct the problem (and that
might work for your antenna too).


-MIKE
  #3  
Old May 1st 04, 04:24 PM
J. Sun
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Default ground loop

Thanks! Mike
I tried the two-baluns trick, it works on TV/Radio path.
Is ther anyway works also on satellite path where the sat
receiver powers the LNB?

(MIKE) wrote in message >...
> Do you have a cable TV connection? These are known to cause ground
> loops. There are isolators available to correct the problem (and that
> might work for your antenna too).
>
>
> -MIKE

  #4  
Old May 1st 04, 10:16 PM
MIKE
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Default ground loop

No, it won't work on a satellite feed. The voltage from the receiver
must go to the LNB amplifier. Do you have the dish AND the LNB grounded
to a water pipe? I do and have no hum problems.


-MIKE
  #5  
Old May 2nd 04, 05:29 PM
J. Sun
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Default ground loop

Looks like we are on the right track. The humming noise does come from
sat path.

I have a aluminum mast into the ground (I guess electrical ground too)
where dish, LNB, HH motor and in-line amp mounted on. The signal goes
through
a 75 feet cable to enter the in-house cable. at the entrace to the
house, I put a grounding blcok connected to house ground but little
help.
My guess is dish is grounded through the mast and the difference
between dish ground and the house ground causes the prolem and your
suggestion works for roof-mounted dish only (my mistake, I did not
make it clear), am I right ?
Thanks!

(MIKE) wrote in message >...
> No, it won't work on a satellite feed. The voltage from the receiver
> must go to the LNB amplifier. Do you have the dish AND the LNB grounded
> to a water pipe? I do and have no hum problems.
>
>
> -MIKE


  #6  
Old May 2nd 04, 07:10 PM
MIKE
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Default ground loop

Would it be possible to isolate the dish from the aluminum mast? A
block of wood would do the trick although a piece of plastic would give
better isolation (the wood could be conductive when wet). I sounds like
you have two different ground potentials - the dish mast and the house
ground. If you isolate the dish from the mast, be sure to run a ground
wire to the house ground from the dish.


-MIKE
 




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