[mythtv-users] Coax splitters - how painful are they?

Brian Wood beww at beww.org
Sun Sep 30 19:00:11 UTC 2007

Jay R. Ashworth wrote:

>> But using directional couplers placed as close to the tap point as
>> possible it allows you to get better control of the final levels.
> Hmmm...

I should elaborate. The DCs used by cable companies these days have
replaceable faceplates, so you can change the tap loss in a few seconds
by just swapping out the plate. Thus if you need more level at the tap
outputs it's a simple plate swapfor a lower tap loss value, albeit at
the cost of lowering the level down the line (the lower value tap loss
plates have a higher insertion loss on the through leg).

A hybrid splitter has a fixed loss per tap, not changeable except by an
attenuator to reduce it or an amplifier to increase it.

Also, hybrid splitters generally do not meet the 30db. tap to tap
isolation spec required by the FCC. If a subscriber's load varies from
an open circuit to a short circuit it is not supposed to effect any
other sub's signal to a noticeable degree.

I've seen TV sets that throw local oscillator products out the RF input,
and without sufficient isolation this can cause problems for other subs
on the same feeder, one of the reasons for the isolation spec.



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