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MFJ-1775 Rotatable Mini-Dipole 

                                                 Instruction Manual 

 

 

7

11) Install the 6-32 screws in all rings of both loading coil assemblies, loosely holding them in place with 

their associated nuts.  Position the screws so the threaded ends of the screws are pointed outward 
towards the two ends of each loading coil assembly as shown in Figure 5. .   

 
NOTE: You can ease your tuning effort by pre-marking the outer ends of the spokes prior 

to installation.  You can do this by placing 1”, 2”, and 3” marks on one end of each 
spoke using a black permanent marker pen.  Then subdivide these marked 
sections into ¼” segments using a red permanent marker pen.  

 
NOTE:  Install the spokes through the rings until they come in contact with the fiberglass 

rod.  This will give you about 1/4” of spoke available to slide back out should you 
trim too much off a spoke during tuning. 

 

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 rings of both loading coil assemblies.  With a 5/16” nut 

driver, tighten the nuts until the spokes are snug. 

 

14) Install four 

short 

spokes in the 10-eter rings of both loading coil assemblies.  With a 5/16” nut driver, 

tighten the nuts until the spokes are snug. 

 
15) Install four 

medium 

(see note below)

 

spokes in the 40 meter rings of both loading coil assemblies.  

With a 5/16” nut driver, tighten the nuts until the spokes are snug. 

 

Note:

   

One or two of the 40 meter medium spokes on one loading coil only may need to be 

replaced with long spokes, depending on the desired 40 meter operating frequency.  See 
the 40 meter tuning instructions below. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

10 M 
coil 

15 M 
coil 

20 M 
coil 

40 M 
coil 

(4) 26” 
spokes 

(4) 12” 
spokes 

(4) 12” 
spokes 

(4) 12” 
spokes 

Figure 5:  Loading Coil Assembly 

AL tube fits 
under this tab 

Loosen to slide 
AL tube under 
the tab 

Screw orientation 

Содержание MFJ-1775

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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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