B2-4 PREPARATIONS FOR SOUNDING 
container is opened, the hygristor should be handled by its metal edges 
with considerable care to insure that contact is avoided between the film 
and the skin of the handler or with other foreign substances. If contact 
with the film should occur, reject the hygristor. Insert the hygristor be- 
tween the clips. Place the edge of the hygristor in the groove of the back 
clip and turn the hygristor until the other edge snaps in place on the 
opposite clip. Move the hygristor back and forth lengthwise several times 
through a short distance to insure a good electrical contact and to test 
the clamp for sufficient tension. If the clamp does not hold the hygristor 
firmly in place, remove the hygristor and bend the two clips together 
slightly. Insert the hygristor and again test for sufficient tension. The 
hygristor should be centered in the space provided and should not touch 
the sides of the radiosonde case, 
(WB) The hygristors are identified by a letter, or combination of letters, 
which is placed on the container in which the element is shipped. Enter 
this identification near the serial number on the calibration chart of the 
radiosonde in which the hygristor is to be used. 
2.7 Installing Hypsometer. If a hypsometer radiosonde is to be used 
and the hypsometer is not anintegral part of the radiosonde, install it by 
placing it under the elastic strap providedonthe side of the instrument. 
2.8 Return Bag. (WB) Whenever a station in the United States uses a 
parachute in the radiosonde train, a cloth mailing bag with shipping tag 
attached should be packed in the battery compartment. Enter the radio- 
sonde serial number, name of station, date, and scheduled time of re- 
lease (GMT) on the front of each tag. Make all entries with typewriter 
Or permanent ink. Stations located outside the U.S. should not include a 
mailing bag or shipping label, regardless of whether or not a parachute 
is included in the train. 
2.9 Securing the Battery Compartment. Secure the battery compart- 
ment with the strings or clamps provided after the return bag, if needed, 
and the battery along with the battery plug have been inserted into the 
battery compartment. 
3. Pre Baseline-Check Tests. All pre-release checks will be made 
without applying manual pressure to the recorder pen. When a zero re- 
cording is to be obtained, the pen must go to zero without manual pres- 
sure and when the sensitivity and baseline-checks are being recorded 
the pen must not be forced, either upscale or downscale. If the recorder 
has been adjusted to the proper zero value, but does not return to this 
point from upscale, or when the penis slow returning to proper record- 
ings during the sensitivity or baseline- checks, the electronics technician 
= Looe FMH#3 
