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

[Niel Skousen]

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