MFJ-5012 MFJ Portable Signal Tracer/Injector
Owner's Manual
2.
Signal Level:
This knob turns the signal generator on and controls the amount
of signal injected into the device under test.
3. AM
Detector:
This switch turns the detector on and off.
4. Audio In:
The audio signal from the device under test enters through this
terminal.
5.
Ground:
The ground of the device under test is connected to this terminal. 6.
Signal Out:
The output of the signal generator is located at this terminal. 7.
Speaker:
Audio from the device under test is heard through the speaker.
The MFJ-5012 is power by a 9 volt battery. The battery connector is accessed by
removing the four screws on the cover. There is a holder mounted in the bottom
of the box for the battery
OPERATION
There are two basic ways or techniques to test amplifier stages in a device using the
MFJ Portable Signal Tracer/Injector.
These two techniques are reflected in the
name itself. The first way is by signal tracing. This is accomplished by
checking for a signal and/or a signal increase at each stage of the device under
test. The second technique is signal injection. This is done by introducing a
signal at each input stage of the device under test and checking for an output.
Signal Tracing
The signal tracing technique is applying a signal to the main input of the _device
Wider lest (DUT) and then checking for the presence of the signal at the input and
output of each stage. When a stage with an input and no output is found,
chances are the problem area has been located. With the DUT and MFJ-5012 off
(both level controls and AM detector), connect the DUT ground to the MFJ5012
ground terminal. Connect a wire or something you can probe with to the Audio In
connector and connect the Signal Out connector to the input of the DUT. Keep all
connections as short as possible, especially the ground connection. Turn the
Audio Level control and the Signal Level control on. Place both controls in the
12 o'clock position. This is just a starting point; you will have to adjust these
controls to accommodate the device that is being tested. Next turn the DUT on. Use
the "probe" to check the input and output to each stage from the main input to
the final output Use the first stage to adjust the level controls. At each amplifier
stage an increase in signal level should occur. Continue to use the Audio Level control
as needed.
Note: If you are testing a device that's using amplitude modulation, make sure
the
AM Detector is on.