dual diplexer problem

Hi,

My satellite guy came while I was at work and threw things together
while my wife and father-in-law watched, but we are having the cable
internet modem problem. I do not understand his reasoning for his set
up. Could someone tell me why he would do the following scenario? And
how to fix it so my cable internet works reliably again.

From the dish he ran one cable to a diplexer in the attic. From this
diplexer he ran one cable down to the receiver on the TV, and another
back to our cable box. (He cut our cable that originally ran from the
cable box to the back of the TV and inserted the diplexer.)

In the cable box is another diplexor which connects the cable from the
cable provider, the cable to my internet modem, and the cable from the
attic.

This is a basic ASCII drawing:

ATTIC CABLE BOX

Cable from Satellite ---+ +-----Cable from Provider
|DPXR+---+DPXR|
Cable to TV-------------+ +------Cable to Internet Modem


Why can't I just have:

ATTIC CABLE BOX

Cable from Satellite ---+ +-----Cable from Provider
| |
Cable to TV-------------+ +------Cable to Internet Modem

With two straight connectors.

Is there a good reason for his connections?

Thanks,

Marty

Run A new Cable from the line out side tothe modem A diplexer won'twork
on the Modem.


--
DFW Tecs
------------------------------------------------------------------------
This message was posted via http://www.satelliteguys.us by DFW Tecs

"DFW Tecs" wrote:

Run A new Cable from the line out side tothe modem A diplexer won't
work on the Modem.


A diplexer that works down to ~5MHz will work with a cable modem.
I've seen it done. Check out the one by PDI:
http://www.cencom94.com/gpage.html4.html

*TimDaniels*

Marty wrote:
Hi,

My satellite guy came while I was at work and threw things together
while my wife and father-in-law watched, but we are having the cable
internet modem problem. I do not understand his reasoning for his set
up. Could someone tell me why he would do the following scenario? And
how to fix it so my cable internet works reliably again.

From the dish he ran one cable to a diplexer in the attic. From this
diplexer he ran one cable down to the receiver on the TV, and another
back to our cable box. (He cut our cable that originally ran from the
cable box to the back of the TV and inserted the diplexer.)

In the cable box is another diplexor which connects the cable from the
cable provider, the cable to my internet modem, and the cable from the
attic.

This is a basic ASCII drawing:

ATTIC CABLE BOX

Cable from Satellite ---+ +-----Cable from Provider
|DPXR+---+DPXR|
Cable to TV-------------+ +------Cable to Internet Modem

That wiring is just plain wrong. The only way it would make sense
is if you swap two diagonal elements.

Why can't I just have:

ATTIC CABLE BOX

Cable from Satellite ---+ +-----Cable from Provider
| |
Cable to TV-------------+ +------Cable to Internet Modem

That wiring makes sense. I'd recommend it.

With two straight connectors.

Is there a good reason for his connections?

Thanks,

Marty

"Zoyburg" opined:
Marty wrote:
This is a basic ASCII drawing:

ATTIC CABLE BOX

Cable from Satellite ---+ +-----Cable from Provider
|DPXR+---+DPXR|
Cable to TV-------------+ +------Cable to Internet Modem

That wiring is just plain wrong. The only way it would make sense
is if you swap two diagonal elements.


Perhaps it doesn't seem to make sense because the
verbal description is quite bad. (It doesn't say where the
"cable box" is, for instance.) If it says that the satellite IF
band (1GHz-1.5GHz approx) is combined at the attic
diplexer with the cable internet band (5MHz-950MHz approx)
and sent down a single coaxial cable to the 2nd diplexer,
and at the 2nd diplexer, the two bands are separated - one
connected to the sat box and the other to the cable modem -
then as long as the two diplexers include freqs as low as
5MHz in their VHF/UHF bands, all is OK and such a scheme
does work. It would be hard to imagine an installer screwing
up such a simple and everyday topology except for using
a diplexer meant to accommodate just cable TV and not
cable TV plus cable internet.

*TimDaniels*