Checks and Adjustments
5-22 1705A Spectrum Monitor
7. Adjust Readout Position
Display the DAC test patternby completing parts a. through c.
a. Press both the 1705A SPAN/DIVbuttons simultaneously to display the
Main Menu.
b. Press eitherS PAN/DIVbutton to move the cursor to TEST, then press
the INPUT button to display the TEST menu.
c. Press eitherS PAN/DIVbutton to move the cursor to DAC, then press
the INPUT button to display the DAC test pattern.
d. ADJUST -- R27 and R29 (HORIZ and VERT POSN READOUT) for a
display crossing atthe crt center.
e. Exit the DAC test patternby first pressing the INPUT button to display
the TEST menu.
f. Press eitherS PAN/DIVbutton to move the cursor to EXIT, then press
the INPUT button twice to returnto a normal display.
8. Adjust 360/119.8MHz L. O.
NOTE. Use an insulated tool for the following adjustments.
a. Adjust the VERTICALPOSITION control so that the crt trace is on the
--70graticule reference line.
b. Connect the signal generatorto J11 (480 MHz IF Input). Setthe output
Frequency for489.7 MHz and the Amplitude to --40 dBm.
c. Select 300 kHz RESOLUTION.
d. Set C55 to full mesh, C69 to 1/8 mesh, and L4 to the top of the coil
(threeslug threads visible).
e. ADJUST --FL1 for maximum signal (three screws beginning at the
outside adjustment screw). If no signal is present, adjust L4 down a few
turns and then adjustF L1.
f. ADJUST -- C55 for maximumsignal. (C55should peak at about 1/8 to
1/2 mesh.)
g. ADJUST --FL1, center and inside screws (do not readjust the outside
screw), formaximum signal. (Lessthan one turn should be required.)
h. ADJUST -- FL2 for maximum signal (threescrews beginning at the back
screw).