[mythtv-users] HD-PVR horizontal bands

[Brian Wood]

On Wednesday, November 17, 2010 01:56:58 pm Greg Oliver wrote:

> > 
> > Interestingly, I have had this same problem with two different STBs
> > (first was the SA3250HD, second is a Cisco RNG-150). I think I'll
> > see if I can find a higher quality, shorter component cable, and
> > if that doesn't work, look into the ground loop isolator. As a
> > side note, aren't there devices that can be clipped on to an
> > existing cable? I seem to recall seeing these somewhere.
> 
> Yeah, you can get magnetic ferrules for the cables,

I think you are talking about ferrite beads or loops. They effectively 
increase the inductance of the cable shield, and thus increase the 
effective reactance to high-frequency (ie: RF) signals.

I don't think they would do anything about common mode (AC hum) type 
problems. It would take a LOT of inductance to impede 50 or 60 Hz. much, 
on the order of many Henrys.

Breaking the ground path with an optical isolator, or using the 
technology used by "Humbuckers" is the only way to solve such problems, 
that or installing a commercial grade ground system.

We used to use these on video lines:

http://puregizmo.com/adc-video-noise-hum-elimination/t.hum-1.shtml

Effective, but pricey, and it takes 3 of them if you are using component 
video.


> but if your hdpvr
> came with the same cables mine did (the 5 wire joined cable), it is
> very high quality (at least mine is)...

Agreed, the 5-cable one that came with my HD-PVR is about as good as 
such cables ever get.

Don't fall into the "Monster Cable" trap of buying things suitable for 
mooring the Queen Mary, they are overpriced and ineffective.