CUSHCRAFT LFA-2M9EL Instruction Manual Download Page 8

Attach your coax to the feed loop using the remaining 8-32 nuts and lock washers.  
Make the distance of the exposed conductors as short as possible.  Seal this connection
using a appropriate sealant to prevent water from entering the coax.  Wind a choke balun
into the coax using a household cleaner or spray paint can.  Put 3 turns around the can and
secure the coax together using cable ties.  Attach the balun to the boom with tape and route 
the coax along the boom to the mast and go down from there.

Tuning

Your antenna is now ready for tuning.  Remove it from your assembly area and mount it on a temporary
mast at least 8 feet off the ground.  Using a SWR analyzer or radio and SWR meter,  check for 
a dip in swr at or about 144.300 MHZ.   You should see a dip in the SWR.  If not, Check all connections
and retest.  If the dip is too low in frequency, move the loop ends in toward the boom.  Move each side the 
same and keep them both the same distance from the boom.  If the dip is too high in frequency, move the 
loop ends out away from the boom.  It is not necessary to tighten the clamps each time for tuning.  Once 
the dip is centered where you want it, tighten the clamps on the tubes.  Do not use a wrench or powered 
device to tighten the clamps.  A nut driver or screwdriver is plenty to do the job.    

Move out to shift frequency down

Summary of Contents for LFA-2M9EL

Page 1: ...ating Equipment 308 Industrial Park Road Starkville MS 39759 USA Tel 662 323 9538 Fax 662 323 6551 VERSION 1A LFA 2M9EL 9 Element Loop Feed Beam For 2 Meters INSTRUCTION MANUAL Cushcraft Amateur Radio Antennas Cushcraft Amateur Radio Antennas ...

Page 2: ...D 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...

Page 3: ...his side of the tube 3 inches from the end This mark will be used to set the insertion depth into the middle boom section If the tubes are put together incorrectly the elements will be out of place and the antenna will not work properly Rear of antenna holes close together Front of antenna Rear boom section Middle boom section This tube is a larger diameter and thicker wall to rear boom section Sh...

Page 4: ...amps and remember they will probably need to be loosened when final alignment of the elements is done Loop Assembly To assemble the feed loop onto the boom you will need the following parts 2 feed loop ends 1 long 7 16 tube 2 short 7 16 tube 1 insulator 8 32 x 1 bolt 8 32 x 2 bolt 8 32 nuts and lock washers ...

Page 5: ...lator using the 8 32 x 1 inch bolt thru the holes in the ends of the tubes Go ahead and tighten the nuts but do not crush the tubes Mount the long 7 16 tube to the third hole from the rear of the boom using a longer 8 32 x 2 1 4 bolt half washer and element saddle 8 32 x 2 1 4 half washer element saddle short tubes with insulator long tube with saddle ...

Page 6: ...ugh friction to stay without the hose clamps being tightened INSTAL THE ELEMENTS R1 D1 D2 D3 D4 D5 D6 D7 Identifying the elements is easy if you have a flat surface Stand all the elements on the flat surface and line them up according to their height The longest will be the reflector and the shortest will the last director D7 Install them on the boom in the proper location using the same half wash...

Page 7: ...Select the parts shown and install the mast plate onto the boom You may balance the boom by installing the plate at the center of gravity of the antenna You can determine this point by simply holding the antenna and balancing it in your hand The other option is to put the plate in the physical middle of the boom This will balance the wind load on the antenna Make sure the elements are in correct o...

Page 8: ...your assembly area and mount it on a temporary mast at least 8 feet off the ground Using a SWR analyzer or radio and SWR meter check for a dip in swr at or about 144 300 MHZ You should see a dip in the SWR If not Check all connections and retest If the dip is too low in frequency move the loop ends in toward the boom Move each side the same and keep them both the same distance from the boom If the...

Page 9: ...tape Check the antenna over one last time to make sure everything is in place and secure If you haven t already Place the plastic end caps over the end of the booms ALWAYS have a friend over to help you install the antenna The antenna is very lightweight but it is awkward to handle NEVER try to install this antenna near power lines or place it anywhere that it can contact power lines if it were to...

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