CM-9521A & CM-9521HD Weight Specification;
We really do not have a weight specification for the CM9521A rotator.
- They were designed for antennas weighing ~15lbs along with a 3ft long upper mast.
- Like many products, we're sure it was over-designed to handle more, but installing something other than ~15lb antenna and an upper mast longer than 3ft, may shorten the life...
- We still have many 25 year old rotators out in the field working fine with 1 or 2, 15 lb antennas on them.
- The upper mast clamps can accept from 1" to a 1 7/8" pipe
- If you are going to run the upper mast through an upper sleeve on a tower, the upper mast must be 1 1/4" in order to rotate "true". (Centered in the upper mast mount.)
- See Fig 2 on page 5 of the CM-9521A Instruction sheet for an example image.
- You can find that Instruction sheet here.
- If you use smaller or larger diameter than 1 1/4", it could seize as it rotates.
- If you are not going to run the upper mast through a sleeve, then the diameter is not as important.
- If you are going to run the upper mast through an upper sleeve on a tower, the upper mast must be 1 1/4" in order to rotate "true". (Centered in the upper mast mount.)
- The lower mast clamps can accommodate from 1", up to ~1 7/8" to 2".
- Also, make certain that you do not have an upper mast over 3ft tall.
- Too tall of upper mast creates excessive leverage in windy situations and can wear on or damage the thrust bearing assembly and upper mount shim bushing.
- Your mast could be damaged by high winds if it is longer than 3ft or if the antenna 'Wind Load projected area', is larger than 3sq ft.
- All of Channel Masters outdoor antennas 'wind load projected area' are less than 3 sq ft, and can be used with the CM-9521A & CM-9521HD rotator systems.
- As an example, the antenna with the highest 'wind load projected area is our CM-4228HD, with a wind load projected area of 2.14 Sq ft.
- Our largest/~100 mile Log periodic/Yagi antennas, 'wind load projected area' are less than 2 sq ft.
You can find the CM-9521A and CM-9521HD installation instructions here.
You can find troubleshooting tips here.