mm wrote:
On Sat, 5 Dec 2009 20:12:17 -0800 (PST), "hr(bob) "
wrote:
Try connecting each set directly by replacing the splitters with thru
connectors and see if they all work ok. This will require that you
undo and redo a bunch of connections as you check out eachset and
associated cables,, but it is the only way to be sure that your basic
components are good. I agree with other posters that bad crimp
connectios are a frequent problem. A little corrosion aftrer 25 years
may make the contact between the outer shield/aluminum ground wire to
the connector outer housing intermittent and that can do wonderous
things. If the output of the dvr is of typical levels, it should
easily drive another set 30 feet away. I have a 3-way splitter on the
output of my cable box and it drives the nearby tv as well as two
other sets 30 feet away, using a 1-3 splitter, with perfect pictures.
When I first got cable tv -- I don't have it anymore --, the guy ran
the cable in through the floor of the close, which overhangs the first
floor. The cable box connected to a channel control dial via a cable,
no infra-red, and I told him I wanted to keep the box in the closet,
out of my way.
He said he wasnt' sure if the tv could that far from the box. The tv
was about 6 feet away.
Later when I connected the first remote tv and was running the co-ax
through the basement ceiling, so for some reason it was 3 times as
long as it would be when I was done, it was about 120 feet and it
still worked fine, but he thought 6 might be too much. (I didnt' get
the slightest impression he was looking for a tip for him to make a
wire 7 feet long, but maybe I'm dense and that's what he wanted??
That didn't occur to me until just now.)
Cable installers are first tier techs. They aren't trained to think,
or troubleshoot. The standard cable between the TV and the converter
was three feet, because that worked with 99% of the TVs in use.
You should see the calculations needed to design a trunkline or
feeder, or even worse, to interconnect two CATV systems. I wrote
software in the mid '80s to allow me to select the hardline by size and
vendor, along with the passives. Our designs called for a minimum of
+10 dB at the tap, but to minimize the number of trunk or bridger
amplifiers. You used a strand map to get accurate distances to
calculate the cable losses, then selected the tap required. That added a
block of loss to the feeder. Each calculation was based on the ones
before it.
--
Offworld checks no longer accepted!