lna

just a few questions i would like to clear up. i'm wanting to get a LNA "low noise amplifier" and i just need some information on a couple things . first will This work as a lna powered only by bias tee? next will This work as a lna powered only by bias tee? Thank to everyone who responds.

I have 4 SDRs that i want to use on one antenna for 800MHz trunking. How can i properly figure out how many sdr dongles i can have connected to it before signal gets too low. Im getting a Nooelec LNA that has +20 Db of gain.