[Elecraft] LONG: Background info on Re: WTB: CPK for Butternut HF-6V

[WILLIS COOKE]

I was curious just what a CPK was, so I Googled it.  I found this URL that would be a good read before you commit to the idea.

http://www.eham.net/forums/Elmers/10424

I had a Butternut HF5V about 18 years ago that was mounted with the base in a tripod on top of a beach house at about 28 feet.  I used four 32 foot radials that sloped down to about 20 feet.  The antenna worked very well and I worked 200 countries with it in a couple of years.  However, the shack was hotter than a two dollar pistol with RF.  Also, I was surrounded with salt water which helps a vertical to no end.  The performance of any vertical depends greatly on both the near field grounding situation and the far field soil conductivity.  The former affects the impedance of the load and the latter the radiation angle.

Willis 'Cookie' Cooke 
K5EWJ


--- On Wed, 8/20/08, Niel Skousen <nskousen at talisman-intl.com> wrote:

> From: Niel Skousen <nskousen at talisman-intl.com>
> Subject: [Elecraft] LONG: Background info on Re: WTB: CPK for Butternut HF-6V
> To: "Elecraft Reflector" <elecraft at mailman.qth.net>, QRP-L at mailman.qth.net
> Cc: w3fpr at arrl.net
> Date: Wednesday, August 20, 2008, 8:59 AM
> Hi Don (and all who have offered advice & help)
> 
> Thanks to all for the input that has been offered.  Based
> on some of the
> comments, I thought I might share the 'rest of the
> story', both to seek
> additional input, and to show the technical trade off's
> associated with
> a compromise antenna environment.
> 
> I'm installing a used HF-6v in a CCR environment, so I
> have some
> environment limitations.  The CCR 'enforcement'
> committee is not
> horribly aggressive, but if I don't aggravate the
> situation, I'm much
> better off.
> 
> I have a 24' tree, with some 3-4' bushes at the
> base, in a desert/rock
> landscaped front yard.  The back has no 'cover'
> yet, and antenna's are
> more visible in spite of a fence.  The plan is to install
> the antenna
> obscured by the tree, in the front yard.  Given the
> landscaping, ground
> mounted with a full radial system is not possible so
> elevating the
> antenna as high as possible without guys or objectionable
> visibility
> wash chosen.  My last HF-6V had 32  ea 32' buried
> radials, wish I could
> reproduce that !
> 
> So, the HF6 will be mounted about 4' off the ground, a
> full elevated
> radial system is not possible.  Choices seem to be the CPK
> solution from
> Butternut or a modified radial system.  Two options are
> being considered
> on the modified radials.
> 
> First, 3 tuned radials (either individual wires for 40/15,
> 30, 20, 15,10
> or the Butternut tuned twinlead variety) could be connected
> at the base
> of the antenna, then run down (hidden in the bushes) at a
> 60 degree
> angle to ground level, then run under/around the rocks. 
> Performance is
> expected to be better than the CPK, but still a compromise.
>  Routing is
>  not linear.  Tuning of this radial environment is expected
> to be a bear !
> 
> The second, the CPK, is expected to be enhanced by the low
> elevation,
> but NOT as effective as a good ground radial system.  I
> might be able to
> enhance this configuration by laying out a psuedo radial
> set of 6-10 8'
> wires at the base of the 4' mast, which would more
> accurately be a
> surface capacitive element to enhance the CPK's effect.
> 
> In neither case will the near field ground losses be
> impacted.  There
> are some spiral wound counterpoise idea's out on the
> web, as well as
> some thoughts on constant angle spirals, which are
> tempting, but at this
> juncture, I expect to lean to the CPK to get it up and
> running, with
> spirals and experiments to follow...
> 
> So any additional input, idea's, are solicited and
> welcome
> 
> Thanks again all,
> 
> Niel
> 
> 
> 
> Don Wilhelm wrote:
> > Remember (or understand if you did not before) that
> elevated radials
> > should be tuned (pruned for length) just like a part
> of the antenna
> > (they *are* part of the antenna).
> > 
> > So get out your antenna analyzer and cut one radial a
> bit on the long
> > side - attach only that one radial to the vertical and
> shorten it until
> > you have the correct readings on the antenna analyzer.
>  Cut the second
> > radial to the same length - move to the next band and
> do the same thing
> > until you are done.  Note that the radials can
> interact on a multiband
> > setup (just like parallel dipoles), so tune the lowest
> bands first and
> > move upward in frequency one band at a time.
> > 
> > The twinlead solution does work, but suffers badly
> from interaction.
> > 
> > 73,
> > Don W3FPR
> > 
> > Jerry Flanders wrote:
> >> At 04:54 PM 8/19/2008, Vic K2VCO wrote:
> 
> >>>
> >>> You don't need an expensive 'kit'!
> Just take any old wire and make
> >>> two 1/4 wavelength radials for each band -- a
> total of 12 radials.
> >>> Try to make them as symmetrical as possible,
> with the two 40 meter
> >>> radials opposite each other, etc.
> >>>
> >>> The ends of the radials must be
> well-insulated, since even though
> >>> they are connected to the coax braid at the
> center, they will develop
> >>> high-ish voltages at the ends.
> >>> -- 
> >>> 73,
> >>> Vic, K2VCO
> >>
> >> Details on making a multiband radial from
> twin-lead are at:
> >> http://www.bencher.com/pdfs/00366IZV.pdf
> >>
> >> Jerry W4UK
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