Can a Rohn 25G be safely self-supporting at ~ 40' with a house bracket at
15', or must it be guyed? The beam will be a 10 lb. Mosley 3el mini-beam
with only 2.5 sq ft of wind surface area.

Is a concrete base essential under these circumstances? I'm planning on
erecting one in the spring and want to plan properly, but don't have much
room for guy wires unless it's unsafe not to use them.


Go here and look in the ON LINE Catalog;

http://www.rohnnet.com/

Look under the GT series of towers.