Honeywell VA201T Calibration Handbook page 81

e) )F THE 3)' LEVEL IS LESS THAN 
SIG and TGT levels are displayed as numbers.
8.  .OW CARRY OUT ONE OF THE PROCEDURES DESCRIBED UNDER /PTIONS
Options
The next procedure to be followed depends on the type of alignment telescope and mounting initially used
to set up the Excel gas detector.
Bayonet-style telescope assembly
If this type of alignment telescope was used with a Trident-type Excel gas detector, there is no need to further
optimize the alignment using the SHC1 Handheld Interrogator.
When the SIG and TGT bar graphs are displayed on the SHC1 screen, SIG will always be greater than TGT
and installation can proceed to the next stage by pressing Enter and following step 12.
Latch-style telescope assembly
If this type of alignment telescope was used with a Trident-type Excel gas detector, there is no need to further
optimize the alignment using the SHC1 Handheld Interrogator.
If this type of alignment telescope was used with a non-Trident Excel it may be necessary to further optimize
the alignment in the following way in order to achieve best performance.
a) After the SIG and TGT bar graphs are displayed on the SHC1 screen as previously described, let the
TGT level reach its initial maximum by waiting for approximately 10 seconds.
During this time the TGT level will move up towards the current SIG level.
b) While watching the SIG level closely, make a small mechanical adjustment in either the horizontal or
vertical alignment and note whether the SIG level goes up or down.
c) If the SIG level goes up, make another small mechanical adjustment in the same direction as before.
d) If the SIG level goes down, change the direction of adjustment. Maximize the SIG level by making small
adjustments in only one plane at a time.
e) When the SIG level has been maximized in one plane, make small adjustments in the other plane until
SIG has been maximized in this plane.
f) Repeat steps (b) to (e) until the SIG level has been maximized in both planes. At this point, SIG must be
bigger than the initial TGT level and any adjustment either side of the current alignment must result in a
reduction in signal level. If not, repeat steps (b) to (e) until these requirements have been met.
g) Lock off the alignment by placing a hex (Allen) key in the pair of grub-screws which control adjustment
in a particular plane and simultaneously rotating them inopposite directions.
h) Repeat this for the other pair of grub-screws.
i) Press Enter and the signal levels are checked. With the SIG level is greater than the TGT level, the signal
check should pass and the screen should display the following message: Signals OK
Notes:
1. If SIG is less than the TGT value the following message is displayed:
2. If SIG is more than the TGT value the screen shows the bar graph screen again.
Searchline Excel
OF THE EXPECTED LEVEL THE BAR GRAPHS ARE NOT DISPLAYED )NSTEAD BOTH
Signals OK
Low Signal
Enter to Retry
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Calibration Handbook