[Elecraft] [KX3] Re: Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

[Wayne Burdick]

"Walter Underwood wunder at wunderwood.org [KX3]" <KX3-noreply at yahoogroups.com> wrote:

> I got the whip for 17m. I figure there is not much difference between a coil at the base of the whip and a coil inside the ATU. Neither one will radiate. So get a whip for the highest band you want to use and let the ATU provide loading for lower bands.

That is not my experience. A high-Q loading coil, combined with the whip, is resonant near a given band and provides much lower loss than a whip of the same length with no coil, matched using the internal ATU. So while the ATU *can* match the whip on bands other than the design band, the farther you get from the design band, the greater the loss. 

That said, a 17-meter whip is a good choice if you want to occasionally use it on 20 and 15 meters and you're willing to accept the comopromise. I'll try to put some numbers this. I have whips for all three bands for comparison. 

When I operate mobile I use a 17-meter whip for this reason. A mobile whip with a larger tunable coil would work much better outside the design band, but my XYL (when she's riding in my CRV) prefers the svelte look of that skinny, single-band radiator :)

Wayne
N6KR


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