Thread: Cushcraft R7
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Old May 21st 04, 06:02 PM
Rick, K6RJ
 
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Richard Clark wrote in message . ..
On Thu, 20 May 2004 08:14:18 -0700, "Just Another Opinion"
wrote:

Richard, Thierry and the original poster I repeat:


Repetition is both tedious and changes nothing.

The R7 is NOT a quarter wave vertical -- it is a half wave end
fed antenna.


Mantras soothe the soul certainly.

A quarter wave radiator needs a ground plane or radials to work against for
sure -- but Cushcraft sez a half wave antenna doesn't need radials as it is
like a horizontal dipole turned vertical and end fed (high impedance) rather
than center fed.


Not needing and prohibiting are not the same thing.

I suggest you read and study the following:

The Cushcraft manual it explicitly states "The
R7 should not be attached to a ground radial system".
URL: http://www.cushcraft.com/support/pdf/r7.pdf


Yeah, and page one:
"System Grounding"

One radial good.
More radial bad.
Yeah, sure.

In fact a word search against the quote above returns 0 hits. So much
for explicit statements and what "should" be read. I note the links
below have the same breathless nature, which is to say a lot of air.


Richard,

I don't know the answer to the main issue of this thread. I just
don't know enough about antennas to speak as an expert. However, as a
point of fact, the R7 manual does state on page 1 under the section
titled "Location":

'Although the R7 will operate in almost any location, it will perform
best if it is mounted vertically and located in the clear away from
surrounding objects such as buildings, trees, powerlines, towers, guy
wires, antennas and metallic objects. The R7 should not be attached
to a ground radial system. Failure to heed these points will possibly
degrade performance, detune the antenna and increase VSWR".

When I clicked on the above link, a PDF file was opened. It appears
that the manual was scanned and stored in PDF. In this case, no text
search would be successful.

FWIW, when I added radials to my R7 I was unable to tune it properly
on all the bands. Once the radials were removed I was able to tune it
up without problems.

Thanks,

Rick, K6RJ