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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

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.

Summary of Contents for LFA-2M16EL

Page 1: ...ng Equipment 308 Industrial Park Road Starkville MS 39759 USA Tel 662 323 9538 Fax 662 323 6551 VERSION 1A LFA 2M16EL 16 Element Loop Feed Beam For 2 Meters INSTRUCTION MANUAL 111 Cushcraft Amateur Radio Antennas Cushcraft Amateur Radio Antennas ...

Page 2: ...RUCTIONS 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 th...

Page 3: ...inches from the end This mark will be used to set the insertion depth into the next size tubing If the tubes are put together incorrectly the elements will be out of place and the antenna will not work properly Use a sharpie or other marking pen to draw a line on the tube THIS MARK IS INDEPENDENT OF THE IDENTIFICATION MARK 285 25 322 1 1 4 x 058 x 72 9 25 46 395 75 360 25 15 25 50 75 1 1 8 x 058 x...

Page 4: ... 3 8 x 058 x 72 2 1 1 2 x 058 x 72 with 1 3 8 x 058 x 65 insert 3 1 3 8 x 058 x 72 4 1 1 4 x 058 x 72 5 1 1 8 x 058 x 72 6 1 x 058 x 16 7 Front of Antenna Rear of Antenna Place a 16 hose clamp over the tube before inserting next section ...

Page 5: ...bolt 8 32 nuts and lock washers 7 16 X 30 7 16 X 14 1 2 Insert each tube 3 inches into the next using the marks you made Try your best to align the holes in each tube Tighten the hose clamps just enough so that the tubes do not move Final alignment of the tubes will likely be needed later Now would be a good time to support the boom on a couple of saw horses or something similar ...

Page 6: ...d 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 2 IN BOLT 2 1 4 IN BOLT 8 32 x 2 8 32 nut 8 lock washer 8 lock washer 8 32 nut Element saddle and half washer Rear of Antenna 7 ...

Page 7: ...er location using the half washer saddle and 8 32 x 2 inch bolts nuts and lock washers Because of different size boom sections some bolts need to be longer to mount the element These bolt lengths are listed on the next page 8 32 x 2 8 32 x 2 1 4 8 32 x 2 1 2 half washer element saddle R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R1 R2 R3 R4 R12 R13 R14 R15 BLACK 0 BROWN 1 RED 2 ORANGE 3 YELLOW 4 GREEN 5 BLU...

Page 8: ...a boom section 3 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 Make sure the elements are in correct orientation before tightening the U bolts Do not allow the mast plate to come within 1 inch of the elements on that section 70 401 119 118 119 118 401 84 85 104 404 32...

Page 9: ... 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 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 po...

Page 10: ...lamp up and down to adjust the tension at first Us the turnbuckles to make fine adjustments to the tension Don t forget the thimbles on each end of the rope they prevent the metal from cutting through when the antenna moves 12 element Antenna shown in vertical position for Illustration only Boom support clamps are installed on the 1 1 4 inch end boom sections 1 4 20 nut 1 4 lock washer 1 4 flat wa...

Page 11: ...MENT R1 1 163790 ELEMENT R2 1 163600 ELEMENT R3 1 163650 ELEMENT R4 1 163650 ELEMENT R5 1 163600 ELEMENT R6 1 163575 ELEMENT R7 1 163550 ELEMENT R8 1 163515 ELEMENT R9 1 163450 ELEMENT R10 1 163400 ELEMENT R11 1 163550 ELEMENT R12 1 163550 ELEMENT R13 1 163550 ELEMENT R14 1 163550 ELEMENT R15 1 178145 DRIVER ELEMENT A 14 1 2 2 178630 DRIVER ELEMENT B 30 1 174022 2MTR LOOP END 2 631570 ROPE 30FT 17...

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