On 4/23/2011 5:30 PM, ZR wrote: >> On 4/23/2011 7:04 AM, ZR wrote: >>> The linear loaded KLM 40 and 80M yagis never lived up to their hype. OTOH >>> the little Cushcraft 2el 40 with loading coils plus a capacity hat way >>> out >>> on the elements is a proven winner. >>> >>> Ive sold one of my 40M 4el KLM's and made a pair of CC style 2el from the >>> other. >>> >>> Carl >>> KM1H >> Some KLM Yagi owners have changed to high Q loading coils made by W6ANR >> and have been happy with the results. >> >> Rick N6RK > Thats interesting Rick. > > One of the CC engineers wrote in QEX that high Q coils was not desired on > their 40M. I dont remember exact details but it should be available thru the > ARRL archives. The author was Rick Littlefield, K1BQT. > > Carl > KM1H Perhaps the reason was mechanical. At some point depending on the current distribution, an additional improvement in unloaded Q of the loading coil will provide diminishing returns in terms of efficiency. Higher Q inductors are generally bigger than there lower Q counterparts (up to a point anyway) which implies more cross-section for the wind to catch. The big W6ANR inductors probably pay bigger efficiency dividends on shortened 80 meter Yagis where the radiation resistance is lower, than they would on a 46 ft long CC 40 meter element.
Mike W4EF............... _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
