[mythtv-users] HDHomeRun(s)

[Brian Wood]

On Thursday 14 January 2010 11:30:09 am Johnny Walker wrote:
> >>> So if you have -10dBmV coming in and put it through a 2 way splitter,
> >>> you now have -13.5dBmV coming out
> >>> the 2 ports.
> >>>
> >>> The 3 output splitter on my house for CATV has
> >>> Input --->  3.5dB loss
> >>>       |->  7dB loss
> >>>       \->  7dB loss
> >>> And so on. So your test environment could affect your reception quality
> >>> as
> >>> well.
> 
> If I have a 5 way splitter which marks each output as -7db does it do
> any good to put a terminator on a single unused output?

You should always terminate any unused outputs, failing to do so will cause 
the device to not be flat across the band, so the actual loss will vary by 
channel. It will also cause return loss type problems.

Hybrid splitters depend on proper termination to work correctly. Directional 
couplers are more tolerant of mismatches on the outputs, one reason they have 
more loss, and cost more.

This is why cable companies use directional couplers to to feed subscribers, 
if a customer has an open or a short on their drop they don't want it to effect 
other subscribers. There is in fact an FCC spec for isolation in cases like 
this, which hybrid splitters can't meet.