Hello, Kevin. You are correct, you will need to power the OT2m. The reason no power cable is supplied is because there are three ways to power the OT2m. It can be powered by the coaxial power jack as well as through a specific pin on the radio and data ports. For now, you may want to consider just powering the OT2m via it's power jack as that is the simplest way if you already have your other cables made for the Nuvi and the T71.
To get the OT2m to know to talk to the Nuvi, and to set some initial parameters that are not (easily) adjustable via the Nuvi, you will need a null modem cable to connect your OT2m to your pc, and use the otconfig.exe program to set the Port A to AUTO mode. After you save that setting to the OT2m, and then follow the instructions for setting up a Nuvi 350 with the OT2m, the OT2m will sense the Nuvi and give the Nuvi the commands it needs to place it into FMI mode. I have a very important question here. Did you get the proper cable to go between the Nuvi and the OT2m? There is a cable specifically made by Garmin to place between the Nuvi and any sort of device that you plan on using the data from the Nuvi. Scott sells them on his site, here is the link: https://www.argentdata.com/catalog/product_info.php?cPath=28&products_id=90 If you aren't into soldering, or just want to make sure the cable is ready to go when you get it, give Scott the small amount extra to put the DB-9 Female connector on there. It can save a lot of hassle that way. :) I also suggest that you get the port splitter or "Y" cable: https://www.argentdata.com/catalog/product_info.php?cPath=21&products_id=93 This allows you to put the Nuvi on the Port B and still allows computer access to Port A to adjust settings without having to disconnect the Nuvi and break the OT2m out of Garmin mode, which can be a pain sometimes. Of course, you will need to use the otconfig.exe program to set Port A to Auto, and then set Port B to GARMIN. I've found that to be the most effective way to run my OT2m's with Nuvi's. :) Good luck with your setup. If you have questions, there are plenty of people on the list here to help. 73, Randy WF5X
