MFJ MFJ-1708B-SDR - Product Overview and Features; Product Features; Connections and Controls

The MFJ-1708B-SDR and the MFJ-1708B-SDRS are RF sensed TR switches with a
receive splitter designed to be used with a transceiver and a separate receiver such as
the popular SDR receivers. The splitter give high isolation between the transceiver and
SDR Receive port to reduce crosstalk and interference between the two ports. The SDR
port has a protection circuit to help prevent damage from transmit RF. The MFJ-1708B-
SDR has a Stripline PCB reducing the SWR up through 450MHz and improved isolation
for better receiver protection.
MFJ-1708B-SDRS has an SMA connector for ease of connection to SDR dongle
receivers.
Features
 RF Sensing for radios that do not have a keying output when transmitting.
 Good isolation between transmit and receive ports.
 Excellent isolation between Transceiver and SDR Receive ports.
 Good SWR characteristics up to 450MHz.
 Receiver protection circuit to limit any transmit RF spikes.
 Control Line input for radios that have a key line output.
 An AUX output that can be set to ground to receive or ground to transmit.
 Power off bypass sets the transceiver to the antenna.
 Adjustable receive delay 50ms to 4 seconds.
Connections and Controls
 REC Connection for the receiver.
 ANT Connection to the antenna.
 XCVR Connection to the transceiver.
 AUX Connection to the receiver mute terminal.
 CTRL Connection to the transmitter PTT or KEY line.
 +12V Power Connector
 DELAY Receive delay adjustment.
ANTSDR REC XCVR
CTRL
+12V
DELAY
PWR TX
RF Sense SDR
Receiver TR Switch
Model MFJ-1708B-SDR
AUX
-
+
ANTSDR REC XCVR
CTRL
+12V
DELAY
PWR TX
RF Sense SDR
Receiver TR Switch
Model MFJ-1708B-SDR-S
AUX
-
+