MFJ-624D Telepatch II Hybrid Phone Patch
Thank you for purchasing the MFJ-624D Telepatch II. We believe
this phone patch with its unique hybrid design is one of the
finest phone 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 624D befo re opera ting, particularly if
you have never operated a phone patch before.
INSTALLATION
The 624D Telepatch IT is designed to remain permanently
installed between your transceiver (or transmitter/receiver),
your modular telephone, and your receiver's speaker. 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.
I. Connection to Telephone.
A . Disconnect the modular phone from its lin e cord.
B. Connect the line cord from the wall jack to the
modular jack on the Telepatch I I labeled L IN E.
C. Connect a second line cord from the modular jac k on
the Telepatch II labeled PHONE to your telephone.
See Figure 1 for
II. Connection to Radio.
A. Radios With Patch IN/OUT Connectors
1. Connect a shielded audio cable from AUDIO IN on
the Telepatch II to PATCH OUT on the radio.
2. Connect a shielded audio cable from AUDIO OUT
on the Telepatch II to PATCH IN on the radio.
3. Connect a microphone to the 8-pi n microphone
jack on the front panel.
pictorial.
4. Connect a speaker to the speaker out jack of
the Telepatch II.
B. Radios Without PATCH IN/PATCH O UT Connectors.
1. 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.
2. Connect the 8-pin microphon e ca ble
to the
mic input on your radio.
3. Connect your micr ophone to th e
jack of the Telepatch II.
mic input
4. Connect a speaker to the SP EAKE R jack on
624D Telepatch II.
FIGURE 1 - INSTALLATION DIAGRAM
C. JUMPER FUNCTIONS.
1. The Telepatch II was shipped from the factory
with Headers HD2 and HD3 set for Kenwood, Icom
and Alinco radios. If you have a Yeasu or Ranger
3500 radio, change the shorting clips on HD2 and
HD3 according to Figure 3.
2. Examine the three jumpers on Headers HD2 and
HD3. Confirm that the jumpers are on the headers
according to the radio with which you are operating
the Telepatch II.
NOTE: If your radio is not listed in TABLE 1, use the header
assignment for Icom if your radio uses Pin I for
transmit audio. Use the Yaesu assignnment if your
radio uses Pin 8 for transmit audio.
2
Radio
HD3 HD2
Icom 2-3,
4-5 1-2
Kenwood 2-3,4-5 1-2
Alinco 2-3, 4-5 1-2
Ranger 3500 1-2, 3-4 2-3
Yaesu 1-2, 3 - 4 2-3
TABLE 1 - Summary of shorting pin assignment.
FIGURE 3 - JUMPERS INSTALLED FOR YAESU AND RANGER AR
3500 RADIOS.
PHONE PATCH ADJUSTMENTS
I. Null Adjustment .
A. Connect a 12 volt DC power supply or adapter such as
the MFJ-1312 to the 2.5 mm (3/32") power input jack on
the rear panel.
B. Turn on the receiver and monitor a QSO in progress.
Adjust the receiver volume on the radio for a
comfortable listening level.
C. Turn the Power switch on the Telepatch II to ON. D.
Push the NULL switch to NULL (IN). F. Push the PATCH
IN/BYPASS to IN.
F. Turn the RECEIVER GAIN control on the Telepatch II
until the VU meter reads about 100 % .
G. Place a call on the telephone to a third party.
H. Adjust the NULL control on the Telepatch II for a null
reading (lowest reading on the VU meter).
I. Set the NULL switch to the NORMAL position.
II. Receiver Gain.
A. Adjust the RECEIVER GAIN control on the Telepatch II
until the audio level into the telephone sounds
about normal according to the third party to whom
you placed the call. This should occur ON VOICE
PEAKS at a level around -10 dBm. The meter is
calibrated to read 100 % (zero VU) when the actual
signal level is -10 dBm.
II. Transmitter Gain.
A. Set the PATCH IN/B YPASS switch to IN.
B. While the person on the phone speaks, adjust the
TRANSMITTER GAIN control on the Telepatch II for
full modulation of the transmitter's mic audio
circuit. Adjust the VOX gain on your radio so the
VOX keys the PTT when. the person speaks and unkeys
your radio when he does not speak. This adjustment
is critical (translated difficult to make) sometimes.
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