Comtech EF Data LTT1450G - Manual (Page 20)

Operation LTT1450G Ku-Band Loop Test Translator
3-2 TM063 - Rev. 1
and level of the external reference signal before proceeding further. See the section on troubleshooting
for more details.
3.1.6 Remote LED
The remote LED will light to indicate that a valid serial command has been issued to the translator. If at
any time the operator manually alters the configuration of the translator from the front panel, the
translator will revert to local operation and update its state from the front panel. A power Off/On reset will
also revert the translator to local control.
3.1.7 LO FAULT
The LO fault indicator will light to signify that a problem exists in either the primary or 25 MHz phase lock
loops of the local oscillator for the currently selected band. This light indicates that the phase lock loop
voltage to the VCO is out of the acceptable range. To identify the loop that is currently at fault, the
operator should either read the LO voltage via serial command or use a voltmeter to manually measure
the loop voltages present at the Test/Fault connector J5 at the rear of the translator. See the
Troubleshooting section for more details.
3.1.8 LCD Display
The LCD display located on the front panel of the converter in the root menu provides and indication of
output attenuation, Input frequency range, output frequency range, and LO frequency. The root menu is
visible on power-up. Two other menus can be seen by pressing the Menu pushbutton. These are the
Status menus which display the phase lock loop tuning voltages of the primary and 25 MHz loops and
the calibration menu. The calibration menu allows for viewing and alignment of the 12-bit DAC look-up
table for the 60 dB pin attenuator.
3.2 Pushbutton Panel
The pushbutton panel provides the means to control the bands selection, and attenuation value of the
translator during normal operation. The functions of the pushbutton and their action visible on the LCD
display are as follows:
Left/Right Pushbutton The left right pushbutton provides a means to position the cursor visible on the
LCD display ether under the attenuation digit of choice or under the band select field which is the Local
Oscillator (LO) field.
Up/Down Pushbutton The up/down pushbutton provides a means to increment or decrement the digit
of attenuation, or to change bands. To change the attenuation, position the cursor under the tens, units or
tenths digit. Pressing the up arrow will increase attenuation. At this time, the output level of the translator
will change to reflect this change on the display.
To mute the output of the translator, position the cursor under the local oscillator fields and press the up
or down arrows. The LO field will scroll to indicate, 2.225 GHz or STANDBY. Note that the RF output
fields change to reflect the output band in relation to the input band minus the LO frequency. In standby
mode, the translator is muted and no signal will be present at the output.
Enter Pushbutton The enter pushbutton provides a means to store a setting or value into nonvolatile
memory. Upon power-up, this will become the default condition. Both the band that was present and the
value of attenuation will be restored upon powerup.