Raytheon Pathfinder 1200 Instruction Manual page 46

5-2
1) Gunn Oscillator tuning
(See Fig.
5-1)
Method A - For two men working at the scanner position and the other at the
display position. They can communicate with one another directly or by telephone,
etc.
a. About 10 minutes after operating the radar, set
I
RANGEl between 0.5 and
3 nm.
b. Rotate the
I
TUNE
I
control of the Display Unit to midposition.
c. Set the
I
SAFETY
I
switch Sl 01 of the Scanner Unit to OFF.
d. Remove the Radome from the pedestal of the Scanner Unit.
e.
Turn antenna array manually until it encounters some solid land echoes.
f. Set the
I
GAIN
I
control so that noise on the sweep trace is discernible.
g. Adjust the mechanical tuning knob of the Gunn Oscillator (A30l) so as to maxi-
mise the echoes on the screen.
Method B - For one man at the scanner position only.
a. Carry out instructions for steps a. through f. of method A, except that the
I
RANGE
I
selector setting can be at any range between 8 and 12 nm.
b. Connect the Circuit Tester on 5 to 10 voltdc range to TB 101-32 with the nega-
tive lead to chassis.
c. Adjust Gunn Oscillator mechanical tuning for a peak reading on the meter.
Note: The Circuit Tester for tuning above mentioned is required its internal resistance more than
lOkD./V.
There may be more than one peak reading. The proper peak
is
the first peak observed
when turning the AD] Screw CW from full CWo