Sounds like you are attempting to download a nightly build... not good... and CM7 is not a good ROM to start with, because you will also have to load the GAPPS file just to get the Google Apps. I don't want to tell anyone what to start with, but I'd have to recommend either Das BAMF Forever 1.0.4, or Gingeritis 3D which are both very good Gingerbread Sense ROMs.
As far as Radio... if you choose one of these two ROMs... go to
[RADIO] HTC Thunderbolt Radios [PG05IMG.zip] (Updated: 23 Aug 2011)... you will need to download the CDMA radio, AND the LTE radio... the latest Gingerbread CDMA radio: From the 2.11.605.0 RUU... and the latest LTE radio: From the 2.10.605.1 RUU
To install the radio after you have the ROM loaded...
To flash the radio, rename the zip to PG05IMG.zip if it's not already and place it on the root of your SD Card. Boot into Bootloader: power off your phone... Turn the phone back on by holding down the volume down rocker and the power button at the same time until the phone opens in bootloader. The zip should start running and updating the radio. Once done reboot the phone on and remove the PG05IMG.zip from your phone, or rename, or move it off the root of the sd card in another folder. If its not moved after the installation it will constantly keep trying to update the radio if you ever need to boot into bootloader again to get to recovery.