Gerhard Fiedler wrote:

> Some have mentioned that some satellite receivers use the connection to
> control the LNB. In this case, I don't think this is the case, or at
> least it doesn't seem to be a problem. The thing is that we have two
> receivers. One is currently not in use, but it could be used. I want to
> connect this second receiver, to a location 50 m away. I figure that if
> I can connect two receivers to the LNB (AFAIK the cable would simply be
> split), the receivers can't do any individual configuration of the LNB,
> or else they could be fighting each other.

If I read you correctly, you want to connect two receivers to one LNB=20
using an RF splitter. That only works if the LNB uses a 'stacked'=20
downconvertor, were the two satellite polarizations (left and right=20
hand) are put into different frequency bands. Cable losses are much=20
higher for the top frequency

block. 950-1450 & 1650-2150 MHz typically.
You have to use 'DC passing' splitter to ensure the LNB gets power.

Most modern LNB's with two outputs have polarity switching built into=20
each port (13v & 18V) so you actually want to run your 2nd receiver=20
directly to the LNB so that it can control polarity switching=20
independently of the other receiver.

The quick test is to split the signal next to your current receiver and
see if the 2nd receiver can access ALL channels independently.
I doubt that it will work fully because whichever IRD is sending out the
higher voltage, will control the polarization sent by the LNB.


> It seems that there is a consensus that
> - I should use separate conduits,
> - I should use heavier cable than normal (CT125 or PF125),
> - it could/should work :)

You should also consider inserting 'in line' signal amplifier to make up=20
for the cable losses. This amplifiers power themselves from the polarity=20
switching voltage. Ideally , half way along the cable, or at the LNB.

You only need heavier cable if the LNB draws enough power that the=20
resistive loss in the cable drops the 'high' polarity voltage below 15V=20
(the typical threshold). You can look up the resistance for the cable=20
you use and compute the loss to see if you drop too much voltage to=20
reliably switch. Most LNB's down regulate to 9V so it's only the=20
switching threshold you have to worry about.


R

--=20
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