tim wrote:
"SteveBell" wrote in
:

OK, you made me get my manual.

The signal loss due to 75-ohm cable length will be 1.5-
6.09 dB
(37%-75%) for every 100 feet of cable, depending on
channel
frequency. 4dB is a good rule of thumb. But in your case,
the
length will be the same, you're just putting a splitter in
the
middle.

The splitter is the killer. A two-way splitter has about a
4dB
loss on each output (61%). For simplicity, assume the
signal is
cut in half. A four-way splitter is electronically the
same as a
two-way with another two-way on each output, so you get
8dB loss
on each output, leaving you with only one-fourth the
signal that
went in.

You also had a splitter outside the house that (two
cables,
remember) that cut the signal in half. The signal that
reaches
your bedrooms will be only 12.5% of the original signal,
and
even less because of the line loss.

These signals are often too weak to work with digital
equipment.
I can tell you from experience that your cable modem needs
a
full-strength signal.

Get a high-quality signal amplifier and install it before
*any*
of the splitters. Keep your runs as short as possible.


In other words, if possible, lose the splitter outside the
house and have only one line to the attic. Put a GOOD amp in
the attic on the one remaining line. Then wire in a four-
way splitter right next to it. Look around and find the
best splitter you can. There is a big difference in
internal losses between the cheap ones and the top-of-the-
line. Forget Radion Shack - find a reputable cable/home
entertainment installer and buy from them. If you can't
find one, go to www.grainger.com and pick out the best
there. Now, to make up for the feed you lost, find the two
shortest runs of the five you want. Feed them from one of
the outputs of the four-way splitter. That way the three
longest runs, or the three drops that have phones/cable
modems/etc. will get the most signal.

Also, make sure you get the F-connectors that solder on.
Any of the connectors that screw/crimp on and use the center
conductor of the RG-6 cable as the center contact will have
more loss and a higher likeleyhood of failure. And make
sure you are using RG-6, not RG-59 or anything else. The
few extra dollars spent here will be more than worth it.

Amp goes as close to antenna as possible- even with high-quality cable,
you will be amplifying noise as well as signal, if it is 50 feet away in
the attic. In 40-some years of amateur cabling, I have never seen a
solder-type Type F connector that goes on a cable end, much less one
with a built-in pin. (not saying they don;t exist, but I have never seen
one.) Your description sounds like the PL-259s we used to use in CB,
back in stone age. Amphenol was the standard. We make Mil-Spec RG6q
cables at work for 2-way satt systems. We use compression connectors, a
higher quality version of what you can find at the Borg. ($200 tool, $5
connectors) They use the center conductor as the pin on the connection,
but the thickness and quality of the conductor are better than retail
cable. The plastic ring, pressed backwards into the connector from the
cable end, holds and waterproofs as well as any soldered connection.
--
aem sends...