MFJ MFJ-44X User Manual
MFJ-44X Scope Adapter
MFJ-44X RTTY
Cross-Pattern Tuning Scope Adapter
Thank you for pur chasing the new MFJ-44X RTTY Cross-Pattern Tuning Scope
Adapter. The MFJ-44X can b e used to filter the audio input of a Terminal Node
Controller, Terminal Unit, or any equipment that decodes mark and space
frequencies (
separate
oscilloscope. When viewed on a scope the output is an elliptical cross-hair display
which provides a accurate means of tuning various amateur radio signals. The MFJ44X will tune ASCII, RTTY, AMTOR, and PACTOR. The scope display can give
the user useful information about the incoming signal, such as:
Mark
•
Is the input Ma rk frequency high or low,
•
Is the input Space frequency high or low,
•
What is the actual frequency shift of the incoming signal?
2125
and
and
Space
2295 Hz)
outputs that can be fed into a monitor scope or a regular
. The MFJ-44X also provides the user with
Installation
JIM: Should we provide an interconnections diagram? It would be easier to
follow
We will now cover installation of the MFJ-44X to a MFJ-1278 and scope.
Installation with other demodulators will be virtually identical. Please follow the
installation procedure closely.
1. Set the POWER switch to the OFF position. Connect an optional MFJ-1312B
or compatible 12 to 16 VDC source to the MFJ-44X. The MFJ-1312B is
available from MFJ. The power jack uses a 2.1mm coaxial connector with
center conductor positive and sleeve ground. Incorrect power supply polarity
can result in damage to the unit.
2. Connect the
output or an
plug should be used with the
portion of a stereo plug is
3. Connect the
MFJ-1278. A 3.5mm stereo (or mono) plug should be used with the
and the
AUDIO IN
EXT
AUDIO OUT
SLEEVE
ground. The
jack, J2 of the MFJ-44X, to either the headphones
speaker output of your receiver. A 3.5mm stereo (or mono)
signal and the
TIP
not used
jack, J1 of the MFJ-44X, to the audio input of the
.
portion of a stereo plug is
RING
1
SLEEVE
ground. The
TIP
not used
RING
signal
.
MFJ-44X Scope Adapter
4. Connect the output of the
scope. The
conductor signal and the shield ground. The inputs on monitor scopes are
usually RCA phono while oscilloscope inputs are BNC. Use a shielded RCA
cable for your monitor scope or make a cable for your oscilloscope with the
center pin signal and the shield ground.
Connect the
the
SPACE
5. Ver ify that all co nnectio ns are c orre ct. If you made or bought pre-made cables
they should be checked for continuity and for shorts (from the shield to the
conductors).
6. (For Oscilloscopes) Place the
This completes the connection of the MFJ-44X to the MFJ-1278. You are now
ready to align the MFJ-44X to your monitor scope.
MARK
to the vertical (Y on oscilloscopes) input.
MARK
and
portion to the horizontal (X on oscilloscopes) input, and
MARK
SPACE
and
SPACE
outputs are RCA phono jacks with the center
TIME/DIV
knob into the XY position.
filters, J4 and J5, to your
2
MFJ-44X Scope Adapter
MFJ-44X to Monitor Scope Alignment
In this section we will align the MFJ-44X to your monitor scope. Please follow this
procedure carefully.
: Before performing the MFJ-44X to scope adapter alignment it is a
NOTE
important that your demodulator is calibrated. Refer to your unit's instructions or
refer to the following for calibrating a MFJ-1278/1278B.
Jim: you should probably divide the 1278 calibration and the 44 alignment.
Also put the directions together and in order for each unit
MFJ-1278 calibration:
1. Apply power to your monitor scope and turn the unit "ON". You may want to
turn the trace INTENSITY to minimum.
2. P lace a push-on jumper at JMP4 in the MFJ-1278.
3. Short pins 1 and 4 of Radio Port 1 in the MFJ-1278.
4. Ensure that the POWER switch
5. Connect the computer and apply power to the MFJ-1278.
6. Set the POWER switch on the computer to the ON position.
7. Load and execute the computer terminal program
8. Set the
computer.
9. Set the MFJ-1278 to the
MODE HB
10. Set the MFJ-1278 into
CALIBRATE
CONVERS
11. Set the
range
12. Remove the top cover from the MFJ-44X.
13. Check the voltage on
MFJ-44X, so the elliptical shaped trace on the scope is
this trace as horizontal as possible.
14. Adjust the
obtain the best elliptical shape possible.
POWER
AUDIO INPUT LEVEL
position.
switch
HF RTTY
<
HORIZONTAL
<ENTER>
Calibration
ENTER
<
ENTER>
pin 9
SW1
of
and
on the MFJ-1278 is set to
SW1
to ON, and sign-on the MFJ-1278 to the
mode by typing:
mode by typing:
>
or K
control
. If the voltage is
U16
VERTICAL
on the MFJ-44X to the
R11
-5 Vdc
horizontal
gain controls o n your scope, to
.
OFF
mid-
, then set R7 on the
. Try to get
3
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