Gently rinse the fresh raspberries in a colander/strainer and let drain. Spread the raspberries on the dehydrating racks evenly and preferably not touching. I have an Excalibur Dehydrator that recommends setting the dehydrator to 135 degrees. The drying time will depend on the humidity of the room where you are dehydrating your raspberries. These took about 20 hours. These were really large raspberries.
After they are totally dry you can preserve your raspberries in mason jars using a FoodSaver. I typically wait about 2 weeks before I seal my dehydrated food in the jars. If you decide to make some raspberry powder, you can use your blender to make some of the dehydrated raspberries into a yummy powder. Keep in mind this will be very concentrated so you will use much less in a smoothie or muffins, etc. I only make powder for a month at a time. Please do not use your FoodSaver to seal the powder it will ruin your unit.