For programming the Radiosonde RS41 you need a adapter from the ST-Link plug (2.5mm) to the sondes plug (2mm).
Please see also the wiki.
I use this parts from my favourite seller:
1 highquality Board (Aisler, see below)
1 connector 2,5mm 5x2 (Reichelt Order BL 2X05G7 2,54)
1 connector 2mm 5x2 (RS Order 144-8150, Reichelt Order MPE 156-3-010)
You can order some boards for 3.-€ plus postage. Please send a Email. You can also order the boards direct at aisler. https://aisler.net/p/MHAIZVEM
Note: They have no shipping costs and send worldwide! You have to order at least 3 boards with a total amound of 8.40€.
The board was created with target.
The connectors are not ideal, but ok. I ordered them at Reichelt Elektronik http://reichelt.de
If you found a better connector, please let me know (incl. ordering info)
Have fun