times when mixing mortar in the wheelbarrow, rarely had problems keeping the 1:3 ratio... without getting the right mix... simply shovel around the shovel...Keep in mind 2 basic things when mixing mortar...
1. Mix for at least 5 minutes after you have added everything.
2. Plastic consistency for 90% of all mortar...
Plastic consistency = pick up a piece of mortar, shape it like a ball. Hold the ball in your hand, shake your hand, the ball should then sink just enough without cracking or falling apart...
With these two points, you'll succeed with the mortar.