[mythtv-users] Digital Signal seems to weaken sometimes

[Roger Heflin]

David Whyte wrote:
> On Sat, Jun 14, 2008 at 11:21 PM, Roger Heflin <rogerheflin at gmail.com> wrote:
>> Given what your symptoms and assuming that you are using a coaxial connection, I
>> would check to make sure the ground is connected on everything.   Check the TV
>> antenna cable, check power to make sure it has a good proper ground.    I have
>> seen antenna cables that don't have the ground connected at all and this does
>> funny things to the signal.   I don't know what the power plugs look in AUS, but
>> in the US there is a ground connection wire, and if you take a voltmeter and
>> measure the resistant from power ground to antenna ground it should be pretty
>> low (way less than 1ohm), if it is not either the power or the antenna has a bad
>> ground connection and you will get all sorts of funny things happening.
>>
> 
> Thanks Roger,
> 
> The adapters that do cause a problem do have a ground wire and the
> ones that don't cause a problem don't have a ground wire.  The TV
> itself doesn't have a ground wire.
> 
> That said, I did mess with the antenna cable in the loft when I was
> putting some Cat5e cable in a couple of weeks ago for this frontend.
> Which part of the coaxial cable would I need to check for a grounding
> issue?  The inner core of the outer-shielding?
> 

The outer shield is supposed to be ground, if they aren't connected too every 
last connector correctly then everything downstream of that connector won't have 
a ground and funny stuff happens.

You will probably have to disconnect it to properly test it, as equipment can 
ground it at one end.

I always make sure that the outer shield makes good connection with the 
crimp/twist on end if it does not make a decent connection you have no ground, 
and funny things happen.


                            Roger