MFJ MFJ-624DM User Manual

Delux Hybrid Phone Patch

Model MFJ-624DM

INSTRUCTION MANUAL

VERSION 0E

CAUTION: Read All Instructions Before Operating Equipment

MFJ ENTERPRISES, INC.

300 Industrial Park Road

Starkville, MS 39759 USA

Tel: [phone] Fax: [phone]

COPYRIGHT 2006 MFJ ENTERPRISES, INC.

C

Introduction

Thank you for purchasing the MFJ-624DM Telepatch II. We believe this phone patch with its unique
hybrid design is one of the finest patches on the market today. This patch is designed to provide
undistorted audio and good receiver to transmitter isolation. The adjustable NULL control allows over
30 dB null in most telephones to provide smooth VOX operation.
Please take the time to completely read the instruction manual to get familiar with the MFJ-624DM
before operation, particularly if you have never operated a phone patch before.

Warning: Only one radio should be connected to the radio at any given time. If
more than one radio is connected damage may occur to the unit or to the
transceivers.

Installation

THE MFJ-624DM can me configured for use with a radio having either a 8-pin round connector or an 8­pin modular connector. The MFJ-624DM is designed to remain permanently installed between a
transceiver, a telephone line with a modular connector, and a telephone receivers handset. The
telephone and the radio will operate as if the phone patch were not in the circuit when the Patch
IN/BYPASS switch is in the BYPASS (out) position.

1. Connection to Telephone

a. Disconnect the modular phone from its line cord.
b. Connect the line cord from the wall jack to the modular jack on the Telepatch II labeled

Line.

c. Connect a second line cord from the modular jack on the Telepatch II PHONE to your

telephone.

2. Connection to Radio

a. Transceivers with Patch IN/OUT Connectors

i. Connect a shielded audio cable from AUDIO IN on the Telepatch II to PATCH

OUT on the radio.

ii. Connect a shielded audio cable from AUDIO OUT on the Telepatch II to

PATCH IN on the radio.

iii. Connect a microphone to the 8-pin microphone jack on the front panel. Only

one microphone should be connected at any given time.

iv. Connect a speaker to the speaker out jack of the Telepatch II.

b. Radios without PATCH IN/PATCH OUT Connectors

The MFJ-624DM has a modular connector on the rear for connection to a transceiver
microphone jack. If the transceiver has a modular connector a cat 5 patch cable can be used
to connect the transceiver with the MFJ-624DM. If the transeiver has an 8-pin round
connector a cable such as the MFJ-5398 should be used. Use the following section to
conifure the jumpers specific to the transceiver being used.

If your radio is listed in the appendix of this manual you can use the pre-tested jumper
confiuragtions shown. MFJ recommends that you check each connection before applying
power to the MFJ-624DM. If your radio is not listed use the following section to determine
the proper jumper settings.

a. Determine which pins of the micrphone connector (either modular or round) are used

for the Mic Audio and the Mic Ground. The wiring for most radio microphones will
be printed in the radio instruction manual. Write the pin numbers in the following
table for reference. Note, some radios have two ground connections on the
microphone. The ground used for PTT ground should be the one used

Description Radio Pin Number
Mic Audio
Mic Ground

b. Jumper Configuration

The MFJ-624DM must be configured specifically for the transceiver being
connected. The MFJ-624DM comes from the MFJ Factory pre-configured to
operate with the ICOM 706 Series.

a. Remove the cover of the MFJ-624DM by loosening the six screws on each

side of the cover. Be careful not to misplace them. Remove the cover from
the chassis and locate the headers on the right side of the board labeled JMP 1
(MIC GND), JMP2 (MIC AUDIO), JMP3 (THRU PASS), JMP4 (MIC
AUDIO).

b. Remove each of the jumpers on each of the headers. A small pair of needle

nose pliers will make this much easier.

c. Using the Pin numbers previously written in the table above and re-place

jumpers in the following order.

i. JMP4 (Mic Audio), place a single jumper on the number

corosponding to the radio pin number previously recorded above.
Note: Only one jumper should be placed on JMP4 (Mic Audio)

ii. JMP2 (Mic Audio), place a single jumper on the number corosponding

to the radio pin number previously recorded above. This will be the
same as in step I above. Note: Only one jumper should be placed on
JMP2 (Mic Audio).

iii.

1. JMP1 (Mic Gnd), place a single jumper on the number
corresponding to the radio pin number recorded above for
Radio Microphone Ground. Note: Only one jumper should be
placed on JMP4 (Mic Audio).

iv. JMP3(Thru Pass) and JMP , place jumpers on the remaining 7 pins

not used on any pins of JMP4, JMP2, JMP1. These jumpers will allow
the microphone to operate the radio just as it would if plugged directly
into the radio.

c. Connect a shielded audio cable from the headphones, speaker out, or monitor out jack

of the radio to the AUDIO IN jack on the Telepatch II.

i. If your radio has an 8-pin modular connector use a CAT 5 ethernet computer

networking cable, such as the MFJ-5397MX, to connect the mic output jack on
the MFJ-624DM and the mic input jack on the radio. If your radio has an 8-pin
round connector a cable such as the MFJ-5398 should be used.

ii. Connect the microphne suppied with your radio to either the 8-pin modular or 8-

pin round mic input jack of the Telepatch II. Only one microphone should be
connected to the MFJ-624DM.