AVCOM PSA-65C Preliminary Operating Instructions page 15

INITIAL TURN-ON & SETUP
1. Turn POWER switch to "LINE" and set the INTENSity control to approx. 80% of fully
clockwise position.
2. Center the VERTICAL POSITION control.
After 30 seconds, a trace should appear on the screen.
3. Set up the analyzer controls as follows:
REFERENCE LEVEL to 0 dBm
SPAN control to 125 MHz/div.
VAR SPAN control to FULL position (Fully clockwise)
SWEEP Rate to 3 o'clock position.
VERTICAL SENSITIVITY to 10 dB/div.
ZERO SPAN toggle switch to the NORMal position.
4. At this time a sweep should be displayed on screen with a large vertical spike (zero
frequency) at the far left side of the display. NOTE: This large signal is ZERO FREQUENCY
and is normal for all spectrum analyzers. (The first LO frequency is equal to the first IF
frequency at that point).
VERTICAL CALIBRATION
1 .
Vertical calibration is very important for accurate absolute amplitude readings. Set SPAN
Switch to 1MHz/DIV and set REF LEVEL SW to 0dBm. Adjust the VERTICAL POSITION
control so that the horizontal baseline is centered between the "Tic" marks between -60
amd -70 dBm. The vertical deflection is now calibrated with the top grid line of the display
equal in amplitude to the setting of the REFERENCE LEVEL control.
NOTE: Once calibrated, do not readjust VERT POS when using other SPAN Settings or
REFERENCE LEVELS.
HORIZONTAL CALIBRATION - (Horizontal Calibration is factory set, however the unit can still
be calibrated in the field by using a tuning tool to turn the recessed HORIZ POSITION
control pot).
1. Position the VAR SPAN control at FULL and using the tuning control, place a signal in
the center in the display. The signal can be an off-the-air signal (set REF LEVEL to 40dBm
for maximum sensitivity and connect a simple antenna to RF INPUT) or the zero frequency
spike. "Expand" the signal spike by rotating the VAR SPAN control counter
clockwise. The signal spike may move to the right or to the left. Adjust the TUNING
control to keep the signal spike centered in the display until the VAR SPAN control is
almost fully counterclockwise. Then rotate the VAR SPAN control clockwise back to
FULL. If the HORIZ POSITION needs adjustment, the signal spike will be displaced to the
left or to the right of the center of the graticule. Adjust the HOR POS control to place the
signal back in the center of the screen. You may want to repeat this procedure and to
perform it at narrow sweep widths for maximum accuracy of the frequency readout.
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