That's what the tune or cw position is for. A low SWR means their is
little power being reflected down to your transmitter. It does not
garantee anything else, but you are likely to be radiating as well as
that antenna system can. Example, a dummy load should have a
1/1 SWR, but naturally, it won't radiate either. The proof is
geting on the air and seeing what you can work.