You can do this if you don't want to modify your Symphony for DC power insertion on the RF output. This bi-directional amplifier uses an external control line to switch between transmit and receive modes. This eliminates the complexity of a homebrew RF sense circuit. The components and design are such that anyone with some experience in microwave circuit construction should be able to build this amplifier. You can then mount this amplifier directly at the antenna or, for a much easier setup, just a few feet away from the Symphony card.
Pictures View some of the construction pictures .
Note that this covers a prototype amplifier . You will need to completely shield the amplifier circuit when it's finished. Scrap copper clad PC board is perfect for this. Don't remove the control line while the Symphony is in operation or you'll end up transmitting into your receive pre-amp. Don't take candy from strangers.