Each roof-top tower comes with two universal mounting plates. The distance between these plates very, depending on the tower model (refer to chart below for dimensions).

Rotating Setups
Usually, a rotator will be mounted on the universal mounting plate located inside the tower. A mast then extends up through the next plate, which will accommodate a thrust bearing (TB-25).

Non-Rotating Setups
To secure a mast in a fixed position, use two mast clamps (MC-10), one on each plate.
 

Model	Height	Distance Between Plates	Base Width
RT-424	4.5'	34.75"	24”
RT-832	8.0'	43.75"	32”
RT-936	9.0'	43.75"	36”
RT-1832	17.5'	37.62"	32”
RT-2632	26'	37.62"	42"