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MFJ-1775 Rotatable Mini-Dipole 

                                                 Instruction Manual 

 

 

5

Step-By-Step Procedure 

 

1)  Set up saw horses or other stable supports (plastic trash cans, chairs, folding tables, etc.) to support 

the antenna during assembly. 

2)  Prepare a temporary 6-8’ ground-level mounting mast for easy initial testing and adjustment.   
3)  Sort the antenna parts into groups of similar parts. Be sure all parts are available. 
4)  After examining the antenna parts, gather the following tools needed for assembly: 

• 

#2 Phillips screwdriver 

• 

5/16" nut driver for #6 nuts and hose clamps. 

• 

Small (4”-6”) adjustable wrench OR 

3/8" wrench for 6 and 2 meter stub nuts 

Two 7/16" open-end wrenches (or wrench and nut driver) for U-bolts and 
center insulator bolts. 

• 

Heavy wire cutters for trimming capacitance spokes 

• 

Pliers for holding the spoke ends as they are trimmed 

• 

Safety glasses. 

 

5)  Assemble the four small "L" brackets to the four long fiberglass insulators with 6-32 x 3/8" screws 

(3 each) and the 6-32 kep nuts (3 each) as shown in Figure 1. 

 

 
 
 
 
 
 
 
 
 

6) Bolt the balun loosely to the 1 x 12” fiberglass rod using the U-bolt set and ¼-20 hardware.  The 

nuts will be tightened when the antenna is mounted on the mast.  See Figure 2. 

 
 
 
 
 
 
 
 
 
 
 

 
 
Note: 

When the balun is mounted as shown, the mast size is limited to 1-3/8” diameter maximum.  

For a 1-1/2” diameter mast, you must mount the balun directly on the mast below the 
fiberglass rod with the additional U-bolt set provided. 

 

Hole for 6 or 2 
meter stub 

Fiberglass 
insulator 

Aluminum 
L-bracket 

6-32 x 3/8 
screws (3) 

6-32 nuts (3)

Figure 1

Fiberglass Rod 

Balun

¼-20 LW& 
nut (2 places) 

U-Bolt set 

Figure 2:  Balun/Center Insulator Assembly – Top View 

Summary of Contents for MFJ-1775

Page 1: ...6 6 Aluminum Stub Channel Bracket 4 808 1796 5 1 x 12 Fiberglass Rod 1 808 1775 12 1 1 8 x 60 AL Tube 2 810 1796 2 30 LONG Spokes 4 810 1796 3C 26 MEDIUM Spokes 8 810 1796 5C 12 SHORT Spokes 24 810 17...

Page 2: ...rsatile rotatable dipole Each HF band uses separate efficient end loading coils wound on fiberglass forms with TeflonTM wire and capacitance hats no lossy traps 6 and 2 meters are full length half wav...

Page 3: ...s mount this antenna so that it is out of the reach of adults and children The capacitance elements can cause injury and or severe RF burns Permanent Installation The ideal installation is a rigid pol...

Page 4: ...e you to lose your balance if it is handled too casually or if the capacitance spokes are snagged on a gutter ladder tree limbs etc 2 Mount the antenna high enough so that it is out of reach The ends...

Page 5: ...bolts Heavy wire cutters for trimming capacitance spokes Pliers for holding the spoke ends as they are trimmed Safety glasses 5 Assemble the four small L brackets to the four long fiberglass insulato...

Page 6: ...n Figure 4 9 Using eight hose clamps four on each radiator clamp the fiberglass insulators so as to support the 16 and 55 threaded rods Position the insulators as shown in Figure 4 10 Mount the four s...

Page 7: ...ng 12 Install four short spokes in the 20 meter rings of both loading coil assemblies With a 5 16 nut driver tighten the nuts until the spokes are snug 13 Install four short spokes in the 15 meter rin...

Page 8: ...ed on a tall support will make adjustments difficult and time consuming It is best to install the antenna on a short temporary mast or pipe that is located in a reasonably clear location for tuning Th...

Page 9: ...as to keep the cut piece from flying off and causing injury The following tips will help you obtain a better SWR on 40 meters than the tuning method used on other bands On 40 meters the lowest SWR is...

Page 10: ...e stub fully extended and 148 MHz with the stub fully contracted NOTE The 2 meter resonance is affected by other resonances in the overall antenna structure You may find a fixed resonance close to the...

Page 11: ...owing hazardous voltages that could create a shock hazard Adequate protection can be accomplished by grounding the shield of the coax to a good earth ground where it enters the building or directly bu...

Page 12: ...SSISTANCE If you have any problem with this unit first check the appropriate section of this manual If the manual does not reference your problem or your problem is not solved by reading the manual yo...

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