EME222 SDR Recever Antenna Switch

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EME222 SDR Receiver Switch Description:

The Software Defined Radio, ( SDR ) RX Switch has been designed to allow an SDR or additional Receiver to be used in conjunction with a HF Radio Transceiver on a single Antenna. The switch provides >70dB isolation protection to the SDR RX when RF is applied to the Radio TRX connection from a 100 Watt HF Transceiver. In receive mode, a two way RF splitter is used to split the incoming Antenna signals between the SDR RX, and Radio TRX connectors. The switch is ideal if you want to use a SDR Play or similar SDR receiver for a spectrum scope on the same Antenna as a HF Transceiver. The switch has a hard wired PTT input that suits most Transceivers, and also an RF detector circuit for further protection incase the hard wired PTT is not connected. When the switch is powered off, the SDR RX connection is terminated into 50ohms, and the Antenna is connected to the Radio TRX connection through the Relays.

Kit Constructors Alert:

1/ There are no current alerts.

Construction Notes:

The images below show both sides of the board. The construction is quite easy if you start with the SMD components on the bottom side of the board first, and then fit the conventional leaded components and connectors after. The only difficult part is the correct orientation of the 2 way splitter. There is a small resistor on the top of the component that should line up with the squiggly line of the board overlay. Click the pictures below for a more detailed view.

EME222 Module Top View
Top view of the EME222 SDR RX Switch
EME222 Module Bottom View
Bottom View of the EME222 SDR RX Switch
EME222-DC Power connections
Picture shows the connections from the DC socket to the toggle switch.
EME222-DC Power connections
Picture shows the connections from the DC socket to the toggle switch.
EME222-Splitter-Mounting
How the 2 Way Splitter is orientated

EME222 SDR RX Antenna Switch Tests:

S21 TX Loss 0.1 to 100MHz
EME222 0.1 to 200MHz S21 Loss from the Radio TRX to Antenna connector when powered off or in TX mode.
S11 TX Return Loss 0.1 to 100MHz
EME222 0.1 to 200MHz S11 Return Loss from the Radio TRX to the Antenna connector when powered off or in TX mode.
SDR Isolation 0.1 to 200MHz
EME222 0.1 to 150MHz S21 Isolation Loss from the Radio TRX to SDR RX connectors when powered off or in TX mode.
S21 RX Loss 0.1 to 200MHz
EME222 0.1 to 200MHz S21 Loss from the Antenna to SDR RX connector when in RX mode. The loss is similar from the Antenna to Radio TRX connection in RX mode.

Changes and Modifications:

1/ To improve intermodulation, D7 and D8 have been changed to SMP1330-005LF PIN Limiter Diodes.