Before you begin, see the general instructions and various sounding accessories presented in Vaisala Guide to Sounding Preparations Technical Reference.
The sounding construction depends on the radiosonde type and if either of the following is used:
- Radar reflector
- Parachute
| Vaisala recommends always to use a parachute in ozone soundings. |
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As the accidental breaking of the unwinder hook might cause the ozone sounding box to
fall with great speed, Vaisala recommends that you tie the unwinder to the parachute
spreader with a string for extra security.
CAUTION For extra security, Vaisala recommends that you tie the radiosonde unwinder to the Totex parachute spreader with a string, or tie extra strong tape around the unwinder hook. - Thread the string through the hole in the unwinder hook (circled in Figure 1) and tie it around the parachute spreader. Make sure the string is slightly longer and looser than the ribbon loop.
- Another option is to prevent the unwinder hook from opening during the flight by tying extra-strong tape such as glass cloth tape, or equivalent, around the unwinder hook. If you do not have this kind of strong tape available, tie the unwinder with a string to the spreader, as explained above.
- If you like, you can also use both options at the same time.
Figure 1. Securing Unwinder with String (on the Left) or Tape (on the Right) 
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If you are using other than a Vaisala-specific Totex parachute model, or a radar
reflector, connect the RSU stabilizer to the unwinder and prepare the balloon string
connection. See Figure 2 for an illustration.
Figure 2. RSU Stabilizer Attached to the Unwinder 
When DMT Model Z ozone sensor is used, the unwinder string is firmly attached to the ring hanger.