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Re: Cross Boom



Joe,

for mid-point mounting of a long helix I would say the metallic boom would
have serious disturbance of the fields/pattern/impedance.  So I would not
recommend it.  

An aside to Hasan's comments: that is very correct.  

Kent made reference to proximity of the cross boom to the nearest elements
and also found that the element tips were most sensitive to detuning.  I
would say that if most are mounting a cross-yagi near mid-point of the
antenna and located between elements that Kent's conditions would nearly be
met.  In addition, is the careful routing of the coax cable close to the
antenna boom and over to the crossboom avoiding coming close to any
elements (esp the tips).  I have mounted my M2-436CP42 at the mfrs clamp
position but redrilled to mount it in "x" configuration and use LMR-400
coax with good performance.  I have not any measurements to back up this
claim, however.

Ed - AL7EB
my 437 18T Helix was end-mounted so the crossboom was behind the reflector.

At 06:56 AM 3/6/2003 -0700, Joe Ennis wrote:
>Lots of feedback on crossed yagis but:
>
>Wondering if there are any results from using a conductive cross
>boom through say, midway on an 8 foot long 70cm or 23cm helix?
>
>Bad idea or go for it?
>
>On Wed, Mar 05, 2003 at 11:53:08PM -0500, Art Goldman wrote:
>> Actually, I just inquired about shipping of those solid 8' masts. It is
>> $40, not because of the weight, but because of the size. They can ship
>> up to 5 masts for the same $40.
>> 
>> UPS charges for a 30 pound item, regardless of weight, if the package's
>
>-- trunc
>
>tia,
>
>-- 
>Joe Ennis - w7net
>AMSAT 20606
>Whitefish, Montana
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