Modifications for OptiBeam OB18-6 antenna

The OB18-6 antenna is a large 40-10M yagi weighing about 255 lbs.  In order to use it with the TiltPlate, there are several modifications to the TiltPlate and the mast/boom plate supplied by Optibeam.   The modification results in a very strong boom to mast connection for this large and heavy antenna.

There is no extra charge to make the modifications however the customer must arrange to have the mast boom plate, both L Brackets and associated hardware sent to me for the modifications.  

Diagram of the TiltPlate and modifications.

Optibeam mast /boom plate before the modifications. 

2 inches of the plate are removed from the top and bottom.

TiltPlate - modifications to the moveable plate

9 holes drilled

2 holes enlarged for the level adjusting bolts which align with 2 holes on the upper OptiBeam L Bracket

KARLock catch block

The slot is widened 0.015 to allow it to fit over the OptiBeam boom/mast plate and L bracket combination which is 14mm (0.055 inch) thick.

Assembled TiltPlate

 Short boom section in place to show there is clearance for the square element bracket bolts between the boom and the TiltPlate.   The KARLock catch arm is installed (if the KARLock option is ordered).

The (3) bolts that attach the UPPER L bracket to the Optibeam boom/mast plate are supplied by Optibeam and are longer than normal since they must pass thru the TiltPlate and Optibeam boom/mast plate. 

The (4) bolts that attach to the boom sections from the backside of the TiltPlate are temporarily installed.  (2 of them are visible in this picture below).   There are supplied by OptiBeam and are longer than the normal bolts since they must pass thru the TiltPlate and Optibeam boom/mast plate. 

The (2) bolts that attach the LOWER L bracket to the Optibeam boom/mast plate are supplied by Optibeam and can be the normal length since they do NOT pass thru the TiltPlate.  

End view

This view shows both of the 2 inch U-Bolts for the "boom truss" mast.   Note, the Optibeam plate is held away from the TiltPlate with thick 1/2 inch washers.  This is to offset the plates to generate the downforce to keep them closed in normal operation.

End View

This view shows the 2 leveling bolts.  Note, also shows the clearance between the boom and the TiltPlate for the square bolts that secure the elements to the boom.