I thought I would update this summit. It has been 10 years since KG7E put up a blog.
if you are planning on doing this summit make sure you do it from Atomic City off of highway 26. If you use Goolgle maps it will suggest you take highway 20 if you are heading from Arco Idaho or Idaho Falls/ Pocatello. if You take Highway 20 you will be going through the Idaho National Energy Laboratory which is closed to the public.
From Atomic City, take the Tabor Rd. south until you see Cedar Butte Rd. Take this and head west. You will be going by Cedar Butte, a 2 pointer, W7I/SI-216. This road will feed into the Big Southern Butte road which goes around the base of the Southern Butte. Make sure you go clockwise, until you reach an old Stage Stop, which is called Frenchman's cabin near 43.429167, -113.057500. From here, if you look Southeast you will see a large canyon going up into the Big Southern Butte. There will be a historical sign on your right about a hundred yards towards the canyon. Take this road until you see a yellow gate and a couple of turnouts. This is the Trailhead. A 4 wheel drive vehicle will be able to go to the summit but if you have a ORV I would suggest you take that. A lot of people also hike the summit from here. It is approximately a 10 mile round trip to the summit. All on BLM land.
Once on the summit, you will see a observation platform which provides a great view of the Snake River Plain. There are rocks and small trees to put up your mast. If you go in the Summer months, go early due to the heat potential and bring plenty of water.
I would recommend that you return the way you came since the road is well established and you could also activate Cedar Butte on the way back.
Keep in mind if you do both, Big Southern Butte is W7I/CI and Cedar Butte is W7I/SI. They are right next to each other but different areas.
Enjoy !
Bill- N0DNF
73