In sci.electronics.repair, on Tue, 25 Aug 2015 16:49:42 -0700,
(Dave Platt) wrote:

In article ,
micky wrote:

Single port power passive passes power to only one of the two output ports.

It has an added capacitor on the unpowered port.

So I only need this if I have an amplifier upstream that needs power?

Are there spliters that pass power to NO ports? I guess there are so
that means power passing splitters have to say that on their label???

If you don't have any devices which need power, and you don't have a
power injector hooked to the coax, then it really doesn't matter
whether the splitter you use passes DC, or not.

The case where you need a splitter which passes power to one port, and
not the other, is whe

- You have a device on one port which needs power (e.g. a satellite
dish and its LNB) and are providing power over the coax, and

- You have a device on the other port which presents a short-circuit
at DC. Many rooftop TV antennas are of this sort, either due to
the antenna itself (folded-dipole driven element) or due to the use
of a 75-/300-ohm balun transformer.

Ah, of course. I'm surprised I lasted this long without coming across
this before, or noticing it on my own. Now I have to review the last
30 years and decide if not knowing this has caused me any problems.
Off-hand, I don't think so, but I've learned it takes days or longer to
retrieve things out of the corners of my mind.