Can Yajirobe suppress his ki?

[Warmmedown]

He was watching Goku vs Vegeta. Most likely he wasn't there by coincidence. So was he not close enough for Nappa or Vegeta's scouter to pick him up?

 

[SSJ2]

The implication is that he can. Raditz picked up powers in the 300s at much farther ranges.

 

[DanielSan]

I would say probably yeah. One cool thing though while it isn't cannon is that he is actually one of two characters in the DBZ BT3 game with the move "hidden energy" which hides his energy and makes it so the opponent loses sight of you.