PREPARATIONS FOR SOUNDING BAe 
On most calibration charts a detent click value will be given. 
In such cases, steps (d) through (j) may be omitted. The pres- 
sure difference (2) minus (1) divided by the detent click value 
gives the number of clicks between the beginning of the con- 
tact (pressure (2)) and the baroswitch setting pressure (1). 
Repeat steps (f) and (g). At the "make," or beginning, of the 
contact representing pressure (2), begin counting clicks and 
turn the detent screw the number of clicks obtained in steps 
(j) or (k) (to the nearest whole number of clicks). If the baro- 
switch-setting pressure is very close to the end of the contact, 
do not continue the detent count beyond the ''make"' of the suc- 
ceeding contact. Do not attempt to count in the direction of 
increasing pressure from the succeeding ''make''; e.g., even 
though the baroswitch setting pressure is very near the end of 
the contact, the detent click setting must always be made in the 
direction of decreasing pressure from the ''make,'' not in the 
direction of increasing pressure from the "break." 
As a check for gross errors, compare the setting visually 
with the indicated position of the baroswitch- setting pressure 
on the calibration chart. 
Example. Assume that the baroswitch-setting pressure (1) at the 
1-1-69 
altitude of the radiosonde is 1001.6 mbs. Inspection of the 
calibration chart shows this pressure is between contacts 4.0 
and 5.0. Pressure (2) corresponding to contact 4.0 is 1006 
mbs. and pressure (3) corresponding to contact 5.0 is 990 
mbs. Pressure (2) minus pressure (1) equals 4.4 mbs. The 
number of millibars per contact (pressure (2) minus pressure 
(3)) equals 16 mbs. Turn the detent screw until the contact 
point rests on approximately contact 1.8. Thenturn the detent 
screw carefully until the contact point just touches contact 4.0. 
At contact 4.0 begin counting the clicks and continue to contact 
5.0. Repeat and obtain the average number of clicks from con- 
tact 4.0 to 5.0; if this is 30 clicks, then the number of clicks 
corresponding to the difference between pressure (1) and pres- 
sure (2) is 30x4,.4=8.3 clicks. After turning the detent screw 
16 
until the contact point rests on contact 1.8 and returning to 
4.0, turn the detent screw 8 clicks towards decreasing pres- 
sure from contact 4.0. This gives the correct pressure-contact 
setting corresponding to the baroswitch-setting pressure. If 
the detent click value is given on the calibration chart, for 
instance .55 mbs, then the number ofclicks corresponding to 
FMH#3 
