I am a under funded newbie ham. I am wanting to set up a base station
at home. Can I make my own rotor cheaply? Maybe using a dc motor or
something? How would I go about doing it? I have a catalog to surplus
center that has many in it.
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First a few questions :
1) What type of rotating antenna do you intend using , a small Yagi ,a large
Yagi , a small or big Quad antenna ?
2) Do you suffer ,from time to time , from high winds in your area ?

Especially heavy rotating antennas with a relatively high wind loading need
a powerful motor/gearbox + a BRAKE !
The latter is an absolute necessity otherwise the internal gear train will
be wasted in a short time.
Another requirement for the rotor is to be weather proof.
If the whole mast , either fitted against a building or other elevated
structure (steel tower) ,is rotating from top to bottom (inside bearings)
the electric rotator can be fitted at ground floor level . This allows some
freedom in selecting electric motor + gear box and brake . In this situation
you might not need an electric drive at all since the rotation could
possibly be established by purely mechanical means ( pulleys +
belt/cable/rope) with a ditto clamp preventing rotation when stationary.

However with the rotator in an elevated position (near the antenna ) a
homebrew unit is probably 'very difficult' .
Perhaps others on this NG would care to comment.

Frank GM0CSZ/KN6WH