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...............
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