Add an Amplified Receive Antenna to the Icom IC-7300

RX Antenna Port Mod

I purchased an “RX7300” from a French ham on Ebay to add a RX antenna port to the IC-7300. It uses SMA connectors, and a little patch cable to bypass the RX antenna port when using a single antenna as usual. Install, was very easy, and required no permanent modifications or soldering. The only improvement I could see for such a kit would be to use a switch, or better yet, a relay, that can switch the RX antenna port on/off instead of using the awkward patch cable. However, for the price, I’m very happy with it.

Bias Tee Injector

TODO

Tx/Rx Switching the Bias Tee Injector

The Bias Tee needs to be powered only when the transceiver is in receive mode. This is accomplished by a fast (~1ms) reed relay connected to the SEND pin of the IC-7300. This pin is normally used for controlling and amplifier, and is connected to nothing (floating) during RX, and goes to ground when transmitting. Using it with the 13.8v pin 8 gives voltage during TX, so the normally open pin of the relay can provide power during RX.

The circuit also includes TX and RX LED indicators, and a Zenier diode/Resistor combo to regulate the voltage down to 5.1v for the LNA. This is inefficient, but noise free, and since the LNA only uses ~30ma, little heat is dissipated anyway.

Low Noise Amplifier Powered by Bias Tee

TODO

Simple Rx Antennas

TODO