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MFJ-1756 Instruction Manual 

6 Meter Ground Plane Antenna 

TUNING THE ANTENNA  

 
After the antenna base with radials has been  secured to the mast, refer to Chart 1 to tune 
the antenna to the desired frequency.  Locate the radiator.  This is the 54 3/4" hollow tube 
that is threaded on the inside at one end.  The radiator length is factory set for  50 Mhz.  
To tune the antenna to other frequencies, cut the radiator with a hacksaw or tubing cutter.  
Do not cut the radiator at the threaded end!  Once the radiator has been cut the change is 
permanent! 
 

Chart 1

  Cutting  measurements for tuning between 50 and 54 Mhz. 

 

FREQUENCY 

RADIATOR LENGTH 

CUT LENGTH 

50 Mhz 

54 3/4 INCHES 

0 INCHES 

51 Mhz 

52 7/8 INCHES 

1 7/8 INCHES 

52 Mhz 

51 INCHES 

3 3/4 INCHES 

53 Mhz 

49 1/8 INCHES 

5 5/8 INCHES 

54 Mhz 

47 1/4 INCHES 

7 1/2 INCHES 

 
After cutting the radiator for the desired frequency, place the 1/4" endcap over the end 
that is not threaded.  This will prevent the antenna radiator from becoming filled with rain 
water.  Attach the radiator to the antenna base by hand threading the radiator over the 10-
32 screw on the top of the base as shown in Figure 9. 

 

 

Figure 9

  Antenna with radiator attached. 

 
After cutting the radiator to the correct length, adjust for lowest SWR by squeezing or 
spreading the center of the matching stub. 
 

Summary of Contents for MFJ-1756

Page 1: ...to a perfect 1 1 SWR Power capability is 1000 watts RF continuous CHOOSING A LOCATION FOR THE ANTENNA WARNING Improper installation and assembly can be hazardous Read these instructions thoroughly be...

Page 2: ...find the following items Before attempting to install this antenna check the parts bag to insure that all hardware is accounted for In the event anything is missing please contact MFJ Enterprises Inc...

Page 3: ...ds through the ceramic insulating post on top of the antenna base Thread the 10 32 nut on the 10 32 screw and tighten with a 3 8 open end wrench Do not over tighten B Locate the hole on the top of the...

Page 4: ...directions Refer to Figure 4 for an illustration of the radial assembly Step 3 Insert a radial through the two left holes located on the front and rear of the base Refer to Figure 3 and the holes lab...

Page 5: ...the radials in place stack the two stainless steel plates together and place them over the radials in the bottom of the antenna base See Figure 5 Place one lock washer on each of the 10 32 Phillips h...

Page 6: ...e U bolt See Figure 6 Figure 6 U bolt assembly B Place the U bolt around the mast not included and install the saddle on the U bolt Be sure the saddle is in the correct position to bite into the mast...

Page 7: ...he other fiberglass plate through the U bolt from the front of the antenna base Place the lock washers over the U bolt and hand thread the nuts on the bolt Tighten the nuts securely with the 7 16 open...

Page 8: ...Cutting measurements for tuning between 50 and 54 Mhz FREQUENCY RADIATOR LENGTH CUT LENGTH 50 Mhz 54 3 4 INCHES 0 INCHES 51 Mhz 52 7 8 INCHES 1 7 8 INCHES 52 Mhz 51 INCHES 3 3 4 INCHES 53 Mhz 49 1 8 I...

Page 9: ...the coax 3 to 4 from the mast for 50 Use an insulator PVC pipe if necessary Below the 50 air spaced length tape the coax to the mast and keep the coax taped against the mast for at least three feet TE...

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