Kantronics MT1200, User Manual

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Pressing S will transmit a constant SPACE until another key is pressed.
Pressing T will transmit a square wave (space/mark) until another key is pressed.
Pressing X will exit the calibrate mode and reset the MT1200.
Drive level.
The drive level is set by a digital controlled pot, which provides an output range of 1 mV
to about 2.0 V p-p, into a 10K load. The default setting of the XMITLVL command is
100, which corresponds to an actual output audio voltage of about 25 mV (into a 600
ohm load). After entering the calibrate mode (CAL), you should use the T option to
initiate the transmission of mark and space tones together. Then, adjust the AFSK drive
level by pressing the ‘–’ or ‘+’ key (and holding it down) until you achieve the drive level
you need. Adjust the level to achieve about 3 kHz deviation from your transmitter.
Alternately, you can send a Mark tone only or a Space tone only, by pressing the M or S
keys. This can be helpful to check the transmitter deviation with each tone.
Equalization.
If there is another Kantronics user nearby, you can have that station transmit a calibrate
signal from their TNC, and choose the R option in your calibrate mode to measure the
status of receive equalization. You will see two numbers displayed each time you press
R. The MT1200 is measuring the mark-space tone levels as received from the other
station. For best performance, the tone levels should be about equal. A ratio of up to
40/60 to 60/40 is acceptable, but a larger difference between the tone levels will cause
problems in decoding the packet signals. Change jumper J2 if need be. Default is no
equalization, since it’s normally not needed.
Note: If you are using a High Impedance Data output from the radio, set J3 plug on one
pin only (OFF = 10 k
Ω , ON = 620 Ω ).
Microprocessor Watchdog Timer
The MT1200 includes a microprocessor watchdog timer. In the unlikely event that its
internal programming gets into an infinite loop, the watchdog timer will detect the failure
and force a reset.
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