KL7UW

RE-DESIGN OF KLM-7LB ANTENNA

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From: "K6myc"
To: "'Edward R. Cole'" 
Subject: RE: KLM-7LB mod to 6m 


HI  ED  
HERE ARE THE DIMENSIONS TO OUR PHONE CONVERSATIONS A FEW MINUTES AGO.
GAIN AT 50.175 SHOWS 13.09 DBI AND F/B 21 DB. I AM NAMING THIS YAGI
"6M6UW" SO I CAN CALL IT UP AGAIN IF NEED BE.

SPACING FROM REFLECTOR                            1/2" ELE HALF LENGTH


              0.000       ----------------------    55.875"
                                Hairpin and 
                                4:1 balun attach 
                                At the x x points.
                                   
             44.375        --------x x---------     51.25 (START LONG & TRIM


             108.625       --------------------     50.813


             197.000       --------------------     49.750


             289.000       --------------------     49.625


             360.000       --------------------     50.062"


CUT THE STRAP PHASING LINE TO 20" AND DRILL HOLES EVERY 1/2" FOR 4" FROM
EACH END SO YOU CAN ADJUST THE LENGTH OF THE "HAIRPIN"

4.5" IN FROM EACH END FOR A 90 DEGREE TWIST IN THE STRAP SO YOU CAN MAKE A
LOOP WITH THE STRAP TO FORM THE HAIRPIN

THE COMPUTER CALCULATED THE HAIRPIN TO BE 3" FROM SIDE TO SIDE AND 5.5" LONG
ON EACH SIDE FOR A TOTAL STRAP LENGTH OF 14 INCHES.  TYPICALLY IT WILL END
UP BEING A BIT LONGER IN THE "REAL WORLD".

ADJUST THE HAIRPIN LENGTH FOR BEST MATCH AND THE DRIVEN ELEMENT LENGTHS FOR
THE FREQUENCY FOR THE BEST MATCH.  OPTIMIZE THE MATCH BETWEEN 50.175 AND
50.225 MHZ

CALL ME IF YOU HAVE PROBLEMS. THE VSWR (COMPUTER VERSION) SHOWS 1.35:1 AT
50.000 MHZ,  1.05:1 AT 50.175 MHZ AND 1.69:1 AT 50.400 MHZ.  YOUR VSWR
BANDWIDTH SHOULD BE SIMILAR.  IF IT IS MUCH DIFFERENT LET ME KNOW.

73, MIKE

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