Of all things I tried to make raspberry jam into a sort of fruit roll up. I had it on a fruit roll up tray and it never got done. All it did was bake onto the tray. Did I do something wrong or is it not possible to do. I tried spreading it thin and did better, but still stuck to the tray pretty good. Can I dehydrate jam?

I'm on the road tonight but had my wife look in our dehydrating book and they do not recommend granulated sugar as a sweetener for fruit leathers. They instead recommend using honey, corn syrup or brown sugar to sweeten them. I don't know what they use for a sweetener in your jam but if it's sugar that may be where your problem lies.
As another thought for you, my wife and I attended a seminar at Canoecopia about dehydrating and someone there made a comment about spraying the sheets lightly with Pam. They said it helped them to keep things from sticking. Don't know if they were including leathers in this but I guess it's worth a try.

It's counter-intuitive. But, I found the more water that I add to purees, the better they dehydrate - it makes them easier to spread with less solids per square inch. I didn't add enough water to the squash that I tried to dehydrate last fall, and it was a bit of a disaster. Maybe I need a better dehydrator....

They aren't my favorite at all. But, I've gotten to be a big raisin fan, because they are a good source of potassium (hard to find), and I can just buy them at the store instead of doing any dehydrating work making fruit leather, etc.

I know when I used to make fruit leather for my son when he was younger we I used to use apple sauce as the base and added flavored jello to it and then put it on the trays.

You must like your jam. Me too, I'm a jammer, I make my own jam. Here is the problem with dehydrating jam. One recipe I use is 3 1/2 cups of fruit & 7 cups of sugar. Add a Tbsp of lemon juice, a tiny bit of butter to keep the foaming action down & pectin. That's it. The amount of liquid from the berries is all that is going to dehydrate, the rest is pure sugar which will not. Jelly is made from fruit juice without the solids, but the sugar ratio is about the same. I make fruit roll ups in my dehydrator, you could stir a small amount of jam into applesauce to give it added flavor or use the method mentioned above by adding jello powder. I recommend using a paper towel with a small amount of canola or vegetable oil to coat your sheets lightly before applying your food.

Whenever I'm making leathers I always put a half dollar sized drop of oil on the sheet and spread it around. You could also try drying it directly on parchment paper.

I'll try some of this

Ben, I've been working on some fruit roll ups for my group trip in June. I use cheap-oh applesauce and water bottle juice packs. 2 cups of apple sauce with whatever juice flavor you want to try. I use one to one and a half packages (for 16 oz. water bottle) for each tray (2 cups apple sauce). Unsweetened applesauce works good too. My current flavors are Crush grape and strawberry, Wal-Mart Great Value Rasperry Ice, and Jolly Rancher watermelon (my favorite). They all taste great. I have the round type of Amer. Harvestor dehydrator. Takes about 18-20 hours at 135 degrees.