... Appearance of the transequatorial microwave chain. (a) - Only some blobs and small chains are present near the complex of ARs 7496 and 7500 located westward from the transequatorial coronal hole observed with the Yohkoh/SXT (d) . b)-(c) - After the C2.1 soft X-ray LDE event , peaked on May 11 at 21:52 UT in AR 7500, a transequatorial microwave chain 1-2-3 is being developed (b) along the narrow part of the coronal hole (e,f) . ... Evolution of the microwave chains of May 11-12, 1993. ...