most recommendations I have read say that you should dry at about 145degF/63degC in order to kill bacteria - I have a thermostat on mine which goes up to 63degC and that is where I dry mine.
the longest I have ever dried beef jerky for was 14 hours due to the thick slices I used. recently I used a jerky cut board and sliced all pieces to exactly 3/8 inch and it took 12 hours to dry. I don't know how powerful the Ronco is but rotating trays 'every 12 hours' seems like an odd instruction. I rotate mine every 2-4 hours. if your dehydrator is not very powerful try thinner slices of jerky but do not dry for too long when the meat is thin otherwise you'll get cardboard. if your slices are 3mm thick I would be surprised if it took longer than 4-6 hours total drying time. 6mm (quarter inch) should probably take 8-10 hours depending on your machine. I checked the ronco site and the 5-try goes to 133F but I couldn't find the 7-tray, I guess it would be similar so that should be enough heat, it then comes down to the power of the fan and how much air it can blast through your machine.
as far as marinading goes, I usually make up my mix and stick into a large ziplock bag and then into another ziplock bag (in case of leaks) and leave in the fridge for 12-36 hours, turning over the bag whenever I remember to. really make sure you get your rubber-gloved hands into the mixing bowl and ensure every piece of meat is covered with your mix before you bag it. once you are ready to load the dehydrator, reserve the excess marinade and spoon/brush over your slices after you turn them over at the 2 or 4 hour mark, it won't make any difference to the drying time but will help to enhance the flavour.
EDIT: just watched the little video clip at http://www.ronco.com/FoodDehydrator/ and it doesn't look like there is a fan in their machines so that will definitely add to drying time. it may be quicker to dry in your oven if it is fanforced, just leave the door slightly ajar and use the temps mentioned above - and still rotate the trays.
the longest I have ever dried beef jerky for was 14 hours due to the thick slices I used. recently I used a jerky cut board and sliced all pieces to exactly 3/8 inch and it took 12 hours to dry. I don't know how powerful the Ronco is but rotating trays 'every 12 hours' seems like an odd instruction. I rotate mine every 2-4 hours. if your dehydrator is not very powerful try thinner slices of jerky but do not dry for too long when the meat is thin otherwise you'll get cardboard. if your slices are 3mm thick I would be surprised if it took longer than 4-6 hours total drying time. 6mm (quarter inch) should probably take 8-10 hours depending on your machine. I checked the ronco site and the 5-try goes to 133F but I couldn't find the 7-tray, I guess it would be similar so that should be enough heat, it then comes down to the power of the fan and how much air it can blast through your machine.
as far as marinading goes, I usually make up my mix and stick into a large ziplock bag and then into another ziplock bag (in case of leaks) and leave in the fridge for 12-36 hours, turning over the bag whenever I remember to. really make sure you get your rubber-gloved hands into the mixing bowl and ensure every piece of meat is covered with your mix before you bag it. once you are ready to load the dehydrator, reserve the excess marinade and spoon/brush over your slices after you turn them over at the 2 or 4 hour mark, it won't make any difference to the drying time but will help to enhance the flavour.
EDIT: just watched the little video clip at http://www.ronco.com/FoodDehydrator/ and it doesn't look like there is a fan in their machines so that will definitely add to drying time. it may be quicker to dry in your oven if it is fanforced, just leave the door slightly ajar and use the temps mentioned above - and still rotate the trays.
I must of had a brain fart when I was reading the post......
plan on eating some of it tommorrow (jerky)