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Section V
5-17. COVER REMOVAL.
5-18. To perform the Adjustment and Calibration
Procedure, it is necessary to remove the two side
covers, each of which is held in place by four screws.
~
USE
ONLY
THE
SCREWS
REMOVED OR ONES OF EQUAL
LENGTH WHEN REINSTALLING
SIDE PANELS. LONGER SCREWS
MAY
DAMAGE
THE POWER
SUPPLY BOARD IF FORCED IN.
5-19. To perform internal troubleshooting or repair
procedures, the side covers and top and bottom
covers must be removed. Remove the two front and
two rear screws in each side casting and remove the
side castings.
- - - - - N O T E - - - - -
Do not remove any screws on the
rear panel.
Remove the rear panel, pulling out the bottom edge
first. Remove one screw from the top and each side
of the chassis shield and slide the chassis off.
5-20. To operate the 209;1 with the chassis shield
removed, connect the power supply in the rear panel
to the pc board.
- - - - - N O T E - - - - -
To operate the instrument with
shield removed, the jumper must be
connected as explained below.
Connect a short clip lead between the chassis section
on which the tuning capacitor is mounted and the
sheet metal tab immediately below it containing the
tapped screw hole.
5-21. The chassis shield should be in place when
doing the Performance Checks.
5-22. ADJUSTMENT
AND
CALIBRATION
PROCEDURE.
5-23. INTRODUCTION.
5-24. The following Adjustment and Calibration
Procedures should be used only if it has been
determined through the Performance Checks that the
Model
209A
is
not
performing
within
its
specifications.
5-25.
If
proper performance cannot be achieved with
the Adjustment and Calibration Procedure, refer to
the Troubleshooting Procedures.
5~
Model209A
5-26. POWER SUPPL Y.
5-27. Before making any adjustments, check the
power supply voltages at test points 2 and 3. These
test points may be reached through the shield cut-out
labeled B+ and B-. They should indicate +21 V and
-21 V respectively, with reference to the shield. If the
voltages are off greater than +/-1 V, troubleshoot the
power supply.
5-28. BIAS ADJUSTMENT.
a. Set the Model209A Range Switch to X1K.
b. Connect the DC Voltmeter to TP4 (BIAS).
c. Adjust R20 (BIAS) for 0 V indication on the
meter.
5-29. AGC ADJUSTMENT.
a. Set the Model 209A RANGE switch to X1K
and the Dial to 2.
b. Connect the DC Voltmeter to TP1 (AGC).
c. Adjust R24 (AGe) for -2.0 Vat TP1.
5-30. AGC AND FREQUENCY ADJUSTMENT.
a. Leave the DC Voltmeter connected as in
Paragraph 5-29, and connect the Model
209A sine wave output to the Frequency
Counter.
b. Set the Model 209A RANGE to X1K and
the Dial to 20.
c. Adjust C3 and C8 (AGC and FREQ CAL)
for 20 kHz and -2.0 V, respectively.
- - - - - N O T E - - - - -
C3 and C8 are interacting controls.
Make one half the apparent needed
correction
in
each adjustment.
Several
adjustments
will
be
necessary.
d. Repeat Paragraphs 5-29 and 5-30 a through c
if the voltage at 2 kHz has changed from -2.0
. V.
e. With the RANGE switch set on X1K, adjust
the Dial for 20 kHz +/-20 Hz on the counter.
f. Without
moving
the
Dial,
check the
frequency on ranges X2 through Xl OK and
record the error in percent.
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