I wouldn't put up 50 feet in Denver without guying it, no matter what the
antenna load. I'm not sure what the recommended base is, but I'd go 3
feet deep and a couple inches bigger all around than the size of the base.
We use to put up 40 foot kent towers this way back in Kansas. Also, it
adds a lot of strength if you cone out the bottom of the hole a couple
inches all the way around.
I'm sure they have a specific size and so forth.
73s
Butch Bussen
wa0vjr