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Modifications for Hy-Gain TH11DX & TH7


The TH11DX is an 11-Element Broadband 5-Band Super Thunderbird Beam for 10, 12, 15, 17, and 20 Meters.  This antenna has 2 phasing tubes that are attached above the boom.  There must be at least 3/4 inch clearance between the phasing tubes and the boom and the TiltPlate.  A special adapter is required.   Modifications to the TiltPlate require drilling some additional mounting holes.  Additional mounting hardware is supplied.  The holes will be drilled and the adapter will be mounted when you receive the TiltPlate.  The diagrams below showing the drill locations are for reference.  There is no additional charge for the adapter when ordered with  a TiltPlate.  A KARLock is also supported with the adapter (if ordered). 


Also supports the TH7 antenna.



Closeup of center sections with boom plate - front view


Closeup of boom plate - rear view



TiltPlate Adapter


The adapter below replaces the boom to mast clamp (not shown above) supplied by Hy-Gain.  The mast clamp supplied by Hy-Gain attaches with 4 bolts (the center 4 holes).   On the TiltPlate, the boom plate is attached to the TiltPlate with 8 bolts using all 8 holes.   This results in a very strong boom connection to the TiltPlate.  The bolts, lockwashers, and nuts are supplied along with the adapter plate. 

(2) 1/4 - 20,  1 1/2 inches long  (top of boom plate)

(2) 5/16 - 18 , 1 1/2 inches long (top of boom plate)

(2) 1/4 - 20,  2 1/2 inches long (bottom of boom plate)

(2) 5/16 - 18 , 2 1/2 inches long (bottom of boom plate)

(6) 1/4 lockwashers

(8)1/4  nuts

(6) 5/16 lockwashers

(8) 5/16  nuts



Diagram of TiltPlate attachment and Adapter


Modification to the moveable TiltPlate


The adapter plate attaches to the TiltPlate

The "bottom" of the boom plate attaches to the adapter

The KARLock (if ordered) attached to the adapter plate about where the text "10 inches" is located.


Inside view shows TH11DX boom plate mounted to the TiltPlate with 8 bolts




Assembly steps

- install the 4 (1  1/2 inch) TOP bolts first,  install lockwashers and nuts on the outside of the adapter plate but leave loose at this time.

- install the 4 (2  1/2) BOTTOM bolts with 3 nuts and lockwashers as shown.   No lockwasher between internal nut and adapter plate.  There is a lockwasher on the outside of the adapter plate side (see picture below).  Leave loose at this time.

- Tighten the TOP bolts

- Tighten the BOTTOM internal nuts to the Hy-Gain boom plate

- Adjust the internal nuts that rests against the adapter plate for proper clearance ( about 1 1/4 inches to 1 3/8 inches).

- Tighten the nuts

You should not need to make any futher adjustments to the leveling bolts as the Hy-Gain boom plate and "fixed" TiltPlate should be parallel.  However you can fine tune the leveling by either adjusting the leveling bolts or changing the gap between the HyGain boom plate and the adapter plate.




"Standard Stackable" TiltPlate,  "stackable" KARLock, and TH11DX adapter.  Complete and ready to ship.