MFJ 1708SDR Instruction Manual

MFJ-1708SDRSDR Instruction Manual SDR Transmit/Receive Switch

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MFJ ENTERPRISES, INC.

300 Industrial Park Road

Starkville, MS 39759 USA

Tel: [phone] Fax: [phone]

Model MFJ-1708SDR

COPYRIGHT 2017 M FJ E NTERP RISES , INC.

VERSION 0A

SDR Transmit/Receive

Switch

CAUTION: Rea d All Instructi ons Before Ope r ating Equipment

INS TRUCTION M ANUAL

MFJ-1708SDR Instruction Manual Transmit/Receive Switch

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INTRODUCTION

Software Defined Radios are becoming commonplace, and often have to work
in conjunction with radio transceivers. Some means of protecting the SDR
input is required while the rig is transmitting. Not all radios have an RF out
(protected) jack, and those that do often require some sort of loopback
connection to completethe receive audio path. Radios with IF outputs do not
allow the full spectrum to be monitored. Some means of antenna sharing is often
required which will isolate the SDR during transmit operations. The MFJ­1708SDR Transmit/Receive Switch will solve this.

TECHNICAL DESCRIPTION

The MFJ-1708SDR T/R switch uses a relay, which switches from transmit to
receive mode. When no power is applied to the unit, it is in the transmit mode.
Once power is applied the relay switches on and the unit is in receive mode.
When the unit senses RF or the control line is grounded from a keyer or PTT
switch, it switches the relay off and the unit is in transmit mode.

The delay adjustment allows you to change how fast the relay switches back to
the receive mode. It is adjustable from 0 to 2 seconds.

The MFJ-1708SDR T/R Switch requires 12 VDC or 110 VAC with MFJ-1312D
power supply.

CONTROLS

Power……………2.1mm Coaxial power input jack with center pin positive and

shield negative
PTT….…………..RCA input jack
Delay…………….Controls time delay for switching
Radio….…………SO-239 Coaxial connector
Antenna………….SO-239 Coaxial connector
SDR….…………..SO-239 Coaxial connector

MFJ-1708SDR Instruction Manual Transmit/Receive Switch

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TECHNICAL ASSISTANCE

If you have any problem with this unit first check the appropriate section of this
manual. If the manual does not reference your problem or your problem is not
solved by reading the manual you may call MFJ Technical Service at 662-323-
0549 or the MFJ Factory at 662-323-5869. You will be best helped if you have
your unit, manual and all information on your station handy so you can answer
any questions the technicians may ask.

You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial
Park Road, Starkville, MS 39759; by Facsimile to 662-323-6551; or by email to
[e-mail]. Send a complete description of your problem, an
explanation of exactly how you are using your unit, and a complete description
of your station.

SCHEMATIC

MFJ-1708SDR Instruction Manual Transmit/Receive Switch

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