Disclaimer:
(1) This is not my work. I've simply collected files from various people/threads in the hopes of saving everyone time and effort. See credits below.
(2) Flashing radios is among the most dangerous thing we can do to our devices. If you flash any of these on your AT&T, T-Mobile, etc., you're very likely to
brick your phone. While I have tested all of these files, you flash at your own risk. Again, this is
Sprint only.
Instructions
Right now, there are different ways to switch radios based on the version you're looking for. Only 1 file is needed for the LG2 radio. Two files for the LEN and LF9 radios. The consensus thus far appears to be that the LG2 radio is the worst of the bunch. YMMV.
Looking for the LG2 Radio?
Flash this file from CWM recovery:
http://www.mediafire.com/file/ve8ed01rpfr328w/SprintGalaxyS3LG2Modem.zip
*****
Looking for the LF9 Radio?
Step 1:
Put this file at the root of the internal SD card (aka /sdcard), not on your micro SD card:
http://www.mediafire.com/file/s3tubbay374io4i/modem.backup
Step 2:
Flash this file from CWM recovery:
Restore Modem Flashable Zip
http://www.mediafire.com/file/qvt2e9gldl7f8b5/SprintGalaxyS3RestoreModem.zip
*****
Looking for the LEN Radio?
Step 1:
Put this file at the root of the internal SD card (aka /sdcard), not on your micro SD card:
http://www.mediafire.com/file/m6j3bfom2pmhqda/modem.backup
Step 2:
Flash the "Restore Modem" flashable zip file from CWM recovery (see above).
--------------
Credit:
First and foremost, Freeza. He's done all the heavy lifting. The LG2 flashable modem is posted here.
http://forum.xda-developers.com/showthread.php?t=1743923
klarthur posted the original "restore modem" zip here:
http://forum.xda-developers.com/showthread.php?p=28816933#post28816933
Naddict posted his LEN backup here:
http://forum.xda-developers.com/showpost.php?p=28872788&postcount=14
I used by own backup of the LF9 modem to share here, though I think the backup was made by Freeza's LG2 upgrade zip.
Lastly... Freeza, if you'd prefer I remove this post, just let me know. If you'd like me to update or change any of the existing files, just holler.