Installation of our Chimney Mount, CM-3080, can be quite simple.
Overview and cautions;
A chimney mount installation is practical only if the chimney is sturdy and vertical. Never mount an antenna on a deteriorated chimney. During moderate to high winds, an un-guyed mast taller than 10 feet can exert enough leverage to break off an unstable chimney. If you choose a chimney mount, use enough mast to place the antenna above most of the smoke and gases. However, to avoid over-stressing the chimney, do not mount the antenna more than 5-10 feet above the top of the chimney. If the height of the antenna must be ~10 feet to receive satisfactory signals, the mast must be properly guyed. The correct method of installing guy wires can be found here. The article is for a slightly different model, but all rules apply. If your mast does not have Guy Rings to attach the guy wires, then you must get creative and cobble together a safe means to attach the guy wires to your mast.
Securing the chimney-mounted antenna and minimizing the stress on the chimney requires the mounting straps to be properly spaced. The top strap should be placed as high up on the chimney as possible. If the chimney has a crown or projecting cap, place the top strap directly under it. The bottom strap should be placed 4 feet below the top strap. If the chimney isn’t long enough to permit this, place the bottom strap as far down on the chimney as possible. If the mast must be 10 feet above the chimney top, don’t use a chimney mount unless you can space the straps at least 30 inches apart. For masts less than 10 feet above the chimney top, the straps should be spaced no less than 24 inches apart.
Contents of Hardware bag include;
- 4) ¼ - 20 Tri-Eyebolts
- 8) ¼ -20 Hex Nuts
- 4) Strap Clamps
- 2) Peak Arch 1 ½” U-Bolt Mast Clamps, ¼ - 20 threads
- 2) 12’ long, 5/8” wide, galvanized metal strapping. (Not in bag)
- 2) Chimney Brackets. (Not in bag)
Assemble one end of one strap to one Eyebolt. Repeat for the 2nd strap.
NOTE; When handling the metal straps, be sure to wear protective gloves. The edge of the strap could cut skin if you slip and are applying sufficient pressure.
- Install a Strap Clamp onto the end of the strapping.
- The crimp tabs should be towards that end of the strapping. IMG_ 3315.
- Pull approximately 4” of the strapping through the eyebolt and fold it over on itself. IMG_3315.
- Move the Strap Clamp so that both portions of the strap go through the same opening. IMG_3319.
- Position the Strap Clamp so that approximately 1” of the folded portion of the strap is exposed past the Strap clamp. IMG_3319.
- Fold that 1” of strapping back over the Strap Clamp and between the crimp tabs. IMG_3320.
- Use a plier or screw driver to form the 1” strapping to conform to the shape of the Strap Clamp. IMG_3321.
- Use a plier to bend the crimp tabs down across the end of the 1” folded back strapping to lock the Strap Clamp in place. IMG_3325.
- Trim excess strapping if needed. Finished strap clamp. IMG_3332.
- Repeat this at one end of the other strap.
Installing the brackets;
- Grasp one strap, at the end with the Eyebolt attached, and insert the threaded end of the Eyebolt into the appropriate hole in the Chimney Mount Brackets. Image ‘CM-3080 Chimney Mt’, shows two Eyebolts installed on the bracket, but at this point you should only have one Eyebolt installed on each strap until step 2.
- Install a hex nut onto the eyebolt, about ½” from the end of the eyebolt. Image ‘CM-3080 Chimney Mt’
- This will leave you room to tighten/adjust the tension of the strapping later.
- Insert the 2nd eyebolt into the appropriate hole in the mounting bracket and secure with a hex nut threaded to about ½” of the end. Image ‘CM-3080 Chimney Mt’, Note; This Eyebolt does not have a strap attached to it yet.
- Wrap the first strap around the chimney, and back to the corner where the mounting bracket is to be placed.
- Install a Strap Clamp onto the end of the strapping. The crimp tabs should be towards that end of the strapping. IMG_ 3315.
- Thread the remaining strapping through the 2nd Eyebolt and pull it tight around the chimney.
- Follow the same instructions for securing the strapping to the eyebolt as was explained above in “Assemble one end of each strap to one eyebolt.”
- If you make the strapping too long, you will not be able to adequately tighten the mount to the chimney.
- Begin to tighten the eyebolt hex nuts in preparation to permanently install the mount and straps.
- Be sure the straps are level, with no kinks or twists.
- Line them up along the nearest course of bricks.
- Straps should be centered on the bricks – not over the mortar joint.
- Tighten it just enough to hold it in place.
Installing the mast;
- Install the U-Bolt Clamps loosely into the Brackets. Image ‘CM-3080 Chimney Mt’
- Insert the mast through the U-Bolt Clamps and tighten the Clamps so the mast cannot slip out.
- Tighten the eyebolt hex nuts so all 4 are in about the same distance from the ends of the eyebolt.
- Make sure the mast is plumb/vertically level, then tighten the eyebolt hex nuts until the mast feels solid in the chimney mounts.
- Loosen the U-Bolt hex nuts enough to remove the mast from the chimney mount.
- Mount the antenna onto the mast.
- Insert the mast back into the chimney mount brackets U-Bolts, point the antenna in the correct direction and tighten the U-Bolt clamps.
- Use zip ties to secure the antenna cable to the mast so it will not move in the wind and damage the cable and matching transformer/balun.