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GENERAL DESCRIPTION

UNPACKING

Unpack the antenna and check the parts against the Parts List and the drawings.  This will simplify
the antenna assembly.  Parts have been separated when possible to aid in assembly.  Make sure you 
have the necessary room to assemble the antenna before unpacking.  This antenna will be very large
when finished.  Try to assemble it in a large open area clear of obstructions and people.  A driveway and
a couple of saw horses or other means of support will make it easy to handle the antenna when putting
it together.   Assembly over grass is not recommended.  There are lots of small things that can get lost
forever in grass.  Some parts may have extras included so don’t worry if you have some left over when 
your done.   The design of the antenna makes it very easy to assemble.  

Tools you will need

WARNING

WHEN INSTALLING YOUR SYSTEM, TAKE EXTREME
CARE TO AVOID ANY ACCIDENTAL CONTACT WITH 
POWERLINES OR OVERHEAD OBSTRUCTIONS.
FAILURE TO EXERCISE THIS CARE COULD RESULT
IN SERIOUS OR FATAL INJURY

2

The LFA (Loop Fed Array) Low-Noise Yagi is very different from the traditional dipole fed Yagi in many ways 
with its primary benefit being unwanted noise rejection. The LFA has a rectangular shaped, full wave loop 
driven element that is laid flat on the boom between and in-line with the parasitic elements .  Then there is the 
way in which the loop functions. The smaller end sections which run parallel to the boom, are engineered to be 
180 degrees out-of-phase with each other. This provides the same effect as is seen within ladder-line feeder; each 
side cancels the other out and therefore, minimum radiation occurs.  In practice this translates to highly 
suppressed side lobes and side-on signal rejection. This feature also plays a role in reducing F/B (Front to Back 
ratio), F/R (Front to Rear ratio) and broad-banding of the antenna too. It is these attributes which help give the 
LFA class-leading all-round performance at almost any boom length and for any given band.

Tape measure in inches.

  A tape measure in feet and inches will do but you will have to convert.

7/16, wrench and/or nut driver
½ inch wrench
Phillips screwdriver
Flat head screwdriver

 for hose clamps

Summary of Contents for LFA-6M7EL

Page 1: ...rating Equipment 308 Industrial Park Road Starkville MS 39759 USA Tel 662 323 9538 Fax 662 323 6551 VERSION 1A LFA 6M7EL 6 Meter 7 Element Loop Feed Antenna INSTRUCTION MANUAL Cushcraft Amateur Radio Antennas Cushcraft Amateur Radio Antennas ...

Page 2: ...IN SERIOUS OR FATAL INJURY 2 The LFA Loop Fed Array Low Noise Yagi is very different from the traditional dipole fed Yagi in many ways with its primary benefit being unwanted noise rejection The LFA has a rectangular shaped full wave loop driven element that is laid flat on the boom between and in line with the parasitic elements Then there is the way in which the loop functions The smaller end se...

Page 3: ...ensive temporary mast Secure the two brackets together using two 2 5 16 18 x 3 bolts lockwashers and nuts Tighten these two bolts evenly until the brackets are snug Note If you use a galvanized 1 1 2 schedule 40 or 80 pipe as a mast it has an O D of 1 9 You will need to put two split lockwashers under the 5 16 nuts on the four long bolts MAST Supplied by customer 1 9 to 2 5 diameter 5 16 x 5 10273...

Page 4: ...ad of the center This will ensure the mark is still visible when the bracket in is the correct spot Start from the rear of the boom and work forward The measurements are given in total inches from the rear of the boom If you need the distance from each element to the next you may subtract the bracket measurements to obtain this value Total distance is given for better accuracy in element placement...

Page 5: ...and directors Do not overtighten the clamps They can be damaged if you use too much torque A nut driver or screwdriver will do the job Do not use a wrench or socket on the clamps A wrench will strip the threads on the band Install the 7 16 tube caps on the ends of the elements 174865 172922 172922 172922 172922 49 1 2 INCHES 174869 175512 1 Loop End Don t tighten loop clamps until final tuning is ...

Page 6: ...t cable as shown You will need to cut the cable to the correct length 30 feet has been supplied Cut this length in half and use one for each side To adjust tension on the cables slide the mount up and down to level the boom Use the turnbuckles for fine adjustment after the clamp has been secured Make sure after your done adjusting to route the wire as shown in the above diagram Looping the wire th...

Page 7: ...al the Coax where the conductors split using an appropriate sealant Water should never be allowed to enter the coax conductor Use of a balun is recommended An example of a coaxial balun is shown below You may use this method or any commercial version you wish Placement of the balun does not have to be at the mast It is better to have it close to the feed point RF Choke 12 turns of RG 8 U with a si...

Page 8: ...ve both sides the same amount Move them a small amount each time and recheck the SWR The dip point should move up as you move the loop ends in toward the boom Continue this adjustment until the frequency you desire has the lowest SWR If the frequency is too high then move the loop ends out away from the boom in the same manner Do not tighten the loop clamps each time you adjust the distance The lo...

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Page 11: ...62961 1 4 LOCK WASHER 55 500392 5 16 18X3 2 500349 5 16 18X5 4 506968 5 16 18X 2 3 4 2 555747 5 16 NUT 9 564792 SPLIT WASHER 5 16 9 5142400 5 16 18X4 1 171329 5 8 CLAMP 2 165919 13 bracket 2 161409 12 bracket 10 170410 boom tube 2 175661 boom tube 2 175667 boom insert 1 475639 7 16 tube cap 8 174869 6 mtr loop end 2 190002 5 8 x 7 5 tube 12 461057 5 8 insulator 2 504069 10 24 x 1 bolt 2 554071 10 ...

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