[Antennaware] 40m vertical questions

[Dave N0RQ]

Greetings.  I'm getting ready to start my first attempt at a 1/4 wave vertical -- for 40 meters.  (Maybe 80m later on.)  Perhaps someone could give a few pointers.

I'm thinking of 1" copper pipe for the first 20' and 1/2" or 3/4" for the remainder.  I could "guy/dacron" it at the 20' mark if it turns out to be necessary.  Is this size copper a bad idea?   (It will have at least 4, probably 8 or more elevated radials (over pretty good ground).)   Then, how do I tell how long to make it?  For a typical dipole, 468 / 7.150 gives me a length of 32' 9", but I know the diameter of the pipe will affect this -- so how do I compute an good length?  (Good guesses are appreciated, too!)

And last questions... what would be a good way to hook the coax to the base of the 1" pipe and radials?

Thanks & 73,
Dave N0RQ