C T I O N; Ajustments; Clear On Stack Zero And Span Calibration30; Zero Reflector Adjustment - EMS 1304 Installation And Operation Manual

Section 5

AJUSTMENTS

Clear on stack zero and span calibration
A clear stack condition must exist to perform this calibration. Power must have been on for no less than 30
minutes. Do not attempt these adjustments in inclement weather. After the cover is removed from the transceiver
normal levels of day light in the area will not effect the calibration.
To complete this procedure the following items are required: EMS Micro-turn
200 on-line test kit (p/n 1232) with a high filter of at least 0.8 O.D.
Swing both the retro and transceiver open and clean the protective
1.
windows (see Figure 4). Return both to the closed position.
Verify alignment, returning beam is centered on the TTL target.
2.
On the transceiver remove the screw below the target viewing window
3.
and pulling the housing straight back until it clears the optical plate.
On the Service Module (Figure 3) make sure the normal/test switch is
4.
in the normal position.
NOTE: All adjustments are on the 222-1667 PC Board (see figure 1).
5.
Adjust the 20 turn Zero potentiometer on board 222-1667 marked "PT
6.
-1", CW for an up scale reading >15%, then slowly CCW for 0-1%
opacity.
PT-1 Zero
Figure 1
Remove the filter and adjust the Zero potentiometer PT-1 for 0-1%.
9.
Insert the High filter again adjust PT-3 for its value, repeat steps until the values come within 0.5 %
10.
Opacity.
Remove the on-line test reflector and replace the transceiver cover and secure the transceiver in place.
11.
You must complete "Zero Reflector Adjustment" procedure next.

Zero reflector adjustment

After clear or off stack zero has been performed the zero reflector needs to be adjusted.
1.
Find and record the zero offset value found in the QUICK MENU under "Zero Cal Value", see
2.
"Zero/Span Calibration Checks" in section 3 for procedure to access the quick menu.
Install the EMS Micro-turn 200 on-line test
7.
reflector on the transceiver and screw the device to the
transceiver with the mounting screw.
thumbwheel adjust the on-line reflector for the same
opacity as in previous step and lock it in place.
Place the highest value filter (for best results at
8.
least a 0.8 O.D.) in the slot provided. Adjust the Span
potentiometer on board 222-1667 marked "PT -3" for
the filters correlated value on the service module
opacity display equals to the correlated value.
See section six (6) for filter correlation
formulas.
30
Figure 3
With the