The cuneiform sign qa, is a common-use sign of the Amarna letters, the Epic of Gilgamesh, and other cuneiform texts (for example Hittite texts).
It has a secondary sub-use in the Amarna letters for ka4.
[1] Linguistically, it has the alphabetical usage in texts for q, a, or qa, and also a replacement for "q", by k, or g.
The qa sign usage in the Epic of Gilgamesh is as follows: qa-(109 times).
[2]