FlightAware Discussions

Request peer review of power injector location

Antenna —(2 feet)— DC Blocker—In-line AMP--------(30 feet)----------------------Power Injector-- DC Blocker—(1 foot)-------Receiver

Will this work?

I want to not have to install an outlet near the antenna for the power injector.

The plan is to put the amp near the base of the mast and then the power injector just before the receiver - about 30 feet away. I have an outlet there.
It seems this should work but I defer to the experts.


EDIT: Fixing my screw up

That will work. These parts are designed to do exactly this.

You might not need any DC blockers, depending on your antenna and power inserter, but there is no harm including them if you are not sure.

I know there are more experienced folks than I on this board so hope they jump in if I’m wrong, but it’s my understanding that the reason for inline amps and power injectors is so the injector can be near a power source and need not to be near the amp which should be as close to the antenna as possible. Regarding the DC blocker near the antenna, unless you have an antenna that is closed loop it isn’t necessary but also not an issue if you do. I think what you propose will work. The closer the amp can be to the antenna the better so if you can, mount it at the base of the antenna.

The antenna is mounted on a 20-foot mast and is about 5-feet above the roof line. So the amp will be about 2-feet from the antenna base. That’s as close as I can get it and still provide some protection from the weather. I was mostly concerned about the fairly long-ish cable run from the injector to the amp. The DC Blockers fall under the category of “If you got 'em, use 'em”.

Thank you to both you guys for your assistance.

overall that setup looks good, though I’d recommend removing the dc block between the power inserter and the receiver. the inserter capacitively couples the receiver end from the outlet side towards the amp. this performs a dc block.

Thank you for that. Will it hurt to leave it? (Just asking…)

no, probably won’t hurt to leave it in. loss through the blocker will be negligible.

in retrospect, I made the assumption you had a power inserter that injected power into only one port, though I recall some are made that inject dc out both ports. in that case you would still want the blocker installed in that location to protect the receiver. all power inserters I’ve used are one way, so I made that assumption.

That’s a fair assumption to make. To be honest I have no idea how this one works.

you got it right. the amplifier can be outside since it is weatherproof. many of the power injectors must be kept dry.

for example, a power injector will typically be installed in the line close to the satellite tv box when used in that application. it usually is used to help power a satellite lnb switch.

the amplifier amplifies everything feeding it including noise. So, don’t look to amplification to solve a noise problem.

In satellite tv runs, you typically would install the amplifier at the mid point of the run to maximize signal at the receiver but you really have a short run so at the antenna is where you want it.

some like to mount their receiver right next to the antenna , which eliminates the amplification issue