[amsat-bb] Re: Cross Boom
Jim Jerzycke
kq6ea at pacbell.net
Thu Apr 23 16:56:44 PDT 2009
Max-Gain Systems sells it.
http://www.mgs4u.com/fiberglass-tube-rod.htm
--- On Thu, 4/23/09, Joe <nss at mwt.net> wrote:
> From: Joe <nss at mwt.net>
> Subject: Re: [amsat-bb] Re: Cross Boom
> To: ka1rrw at yahoo.com
> Cc: "Jeff Yanko" <wb3jfs at cox.net>, "Billy Simpkins" <bsimpkins31 at dishmail.net>, "Edward Cole" <kl7uw at acsalaska.net>, kq6ea at pacbell.net, amsat-bb at amsat.org
> Date: Thursday, April 23, 2009, 3:43 PM
> Just follow the suggestions on the web page that was
> suggested and you'll be fine.
>
> But I am curious as to where did you find the 1.25"
> fiberglass riod?
>
> Joe
>
> MM wrote:
>
> >
> > Thanks for all of the good information.
> >
> > I am going to rebuild my Sat array this spring (its
> time for a routine overhaul).
> > I have a M2 436CP42UG and the M2 CP22 at opposite ends
> of a 12’ (1.25”) solid fiberglass pole. I am converting
> over to a 1.5” sold 14-foot fiberglass pole to give me
> better clearance for other antennas on the tower. Kenpro
> 5500 AZ/EL
> >
> > I never liked hanging the coax off the back since is
> throws off the balance.
> > When you slide the U-clamps Backward on the M2 boom to
> compensate for the coax weight on the back, you end up with
> the clamps on Thinner section of the Boom.
> >
> > Based on the theories, if I follow the coax routing
> and avoid the half or full wave points I may be able to run
> the coax down the boom?
> >
> > Would this work on the 70 cm too?
> >
> > Thanks Miles
> >
> >
> > --- On Thu, 4/23/09, Jim Jerzycke
> <kq6ea at pacbell.net> wrote:
> >
> >
> >> From: Jim Jerzycke <kq6ea at pacbell.net>
> >> Subject: [amsat-bb] Re: Cross Boom
> >> To: "Jeff Yanko" <wb3jfs at cox.net>,
> "Joe" <nss at mwt.net>, "Billy
> Simpkins" <bsimpkins31 at dishmail.net>,
> "Edward Cole" <kl7uw at acsalaska.net>
> >> Cc: amsat-bb at amsat.org
> >> Date: Thursday, April 23, 2009, 1:41 AM
> >> It's here on Howard's site:
> >> http://www.g6lvb.com/fibermetalboom.htm
> >>
> >>
> >> --- On Wed, 4/22/09, Edward Cole
> >> <kl7uw at acsalaska.net> wrote:
> >>
> >>
> >>> From: Edward Cole <kl7uw at acsalaska.net>
> >>> Subject: Re: [amsat-bb] Re: Cross Boom
> >>> To: "Jeff Yanko"
> <wb3jfs at cox.net>,
> >>>
> >> kq6ea at pacbell.net, "Joe"
> <nss at mwt.net>,
> >> "Billy Simpkins"
> <bsimpkins31 at dishmail.net>
> >>
> >>> Cc: amsat-bb at amsat.org
> >>> Date: Wednesday, April 22, 2009, 10:39 PM
> >>> The coax shield coming off the antenna boom at
> a right
> >>>
> >> angle
> >>
> >>> looks like another parasitic element being
> added to the
> >>>
> >> antenna
> >>
> >>> causing severe distortion of the antenna
> pattern. But if one
> >>> installs the antenna in the X configuration
> and attach the cross
> >>>
> >> boom in
> >>
> >>> a location away from any of the elements one
> can tightly
> >>>
> >> run
> >>
> >>> the coax across the metallic cross boom with
> little effect.
> >> This
> >>
> >>> was tested by WA5VJB and is a published
> article.
> >>>
> >>> I have my M2 436CP42UG mounted in this fashion
> and it
> >>> preforms well.
> >>>
> >>> 73, Ed - KL7UW
> >>> maybe someone else can point to the link to
> that
> >>>
> >> article.
> >>
> >>> At 11:41 AM 4/22/2009, Jeff Yanko wrote:
> >>>
> >>>> OK, I see where this is coming into play.
> So
> >>>>
> >> it's
> >>
> >>> possible that the coax
> >>>
> >>>> shield could react to the feedpoint system
> and
> >>>>
> >> pattern.
> >>
> >>> Now this raises a
> >>>
> >>>> question. If this is the case, has
> anybody tried
> >>>>
> >> a
> >>
> >>> broadband choke balun to
> >>>
> >>>> limit this potential problem? If you
> think about
> >>>>
> >> it,
> >>
> >>> the bigger issue with
> >>>
> >>>> coax effecting the radiation pattern is
> improper
> >>>>
> >>> decoupling of the fed
> >>>
> >>>> point. If the outside shield is hot with
> RF it
> >>>>
> >> will
> >>
> >>> radiated and effect the
> >>>
> >>>> pattern big time. If the coax is properly
> >>>>
> >> decoupled at
> >>
> >>> the fed point the
> >>>
> >>>> outside shield will ideally have zero rf
> current
> >>>>
> >> on it
> >>
> >>> and ideally have no
> >>>
> >>>> impact on the pattern.
> >>>>
> >>>> Thoughts?
> >>>>
> >>>>
> >>>> 73,
> >>>>
> >>>> Jeff WB3JFS
> >>>>
> >>>>
> >>>> ----- Original Message -----
> >>>> From: "Jim Jerzycke"
> >>>>
> >>> <kq6ea at pacbell.net>
> >>>
> >>>> To: "Joe" <nss at mwt.net>;
> >>>>
> >> "Billy
> >>
> >>> Simpkins"
> <bsimpkins31 at dishmail.net>;
> >>>
> >> "Jeff
> >>
> >>>> Yanko" <wb3jfs at cox.net>
> >>>> Cc: <amsat-bb at amsat.org>
> >>>> Sent: Wednesday, April 22, 2009 11:09 AM
> >>>> Subject: Re: [amsat-bb] Re: Cross Boom
> >>>>
> >>>>
> >>>>
> >>>>> Because the shield of the coax
> >>>>>
> >> "looks"
> >>
> >>> like a piece of pipe, and has the
> >>>
> >>>>> same effect on the antenna pattern
> that
> >>>>>
> >>> you're trying to eliminate by
> >>>
> >>>>> going to a non-metallic cross-boom.
> >>>>> Jim KQ6EA
> >>>>>
> >>>>>
> >>>>> --- On Wed, 4/22/09, Jeff Yanko
> >>>>>
> >>> <wb3jfs at cox.net> wrote:
> >>>
> >>>>>> From: Jeff Yanko
> <wb3jfs at cox.net>
> >>>>>> Subject: [amsat-bb] Re: Cross Boom
> >>>>>> To: "Joe"
> <nss at mwt.net>,
> >>>>>>
> >>> "Billy Simpkins"
> >>>
> >> <bsimpkins31 at dishmail.net>
> >>
> >>>>>> Cc: amsat-bb at amsat.org
> >>>>>> Date: Wednesday, April 22, 2009,
> 10:55
> >>>>>>
> >> AM
> >>
> >>>>>> Hi all,
> >>>>>> I found this line confusing....
> >>>>>>
> >>>>>> "But then if you go
> insulated
> >> then do
> >>
> >>> not run the
> >>>
> >>>>>> feedline along it either
> >>>>>> or you just defeated the purpose
> of the
> >>>>>>
> >>> insulated
> >>>
> >>>>>> boom."
> >>>>>>
> >>>>>> My question is if you run the coax
> along
> >>>>>>
> >> an
> >>
> >>> insulated
> >>>
> >>>>>> crossboom, ie.
> >>>>>> fiberglass, how could that affect
> the
> >>>>>>
> >>> coupling of the
> >>>
> >>>>>> transmission line when
> >>>>>> the object it is being attached to
> is
> >>>>>> "insulated"?
> >>>>>>
> >>>>>>
> >>>>>> 73,
> >>>>>>
> >>>>>> Jeff WB3JFS
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> ----- Original Message -----
> >>>>>> From: "Joe"
> >>>>>>
> >> <nss at mwt.net>
> >>
> >>>>>> To: "Billy Simpkins"
> >>>>>> <bsimpkins31 at dishmail.net>
> >>>>>> Cc: <amsat-bb at amsat.org>
> >>>>>> Sent: Wednesday, April 22, 2009
> 7:06 AM
> >>>>>> Subject: [amsat-bb] Re: Cross Boom
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>> It all depends on how the
> elements
> >>>>>>>
> >> are
> >>
> >>> mounted.
> >>>
> >>>>>>> If at 45 to 90 degrees from
> the
> >>>>>>>
> >>> crossarm, no propblem
> >>>
> >>>>>> and use anything,
> >>>>>>
> >>>>>>> But if in the same plane then
> need
> >>>>>>>
> >>> insulated
> >>>
> >>>>>> crossboom,
> >>>>>>
> >>>>>>> But then if you go insulated
> then
> >>>>>>>
> >> do
> >>
> >>> not run the
> >>>
> >>>>>> feedline along it
> >>>>>>
> >>>>>>> either or you just defeated
> the
> >>>>>>>
> >> purpose
> >>
> >>> of the
> >>>
> >>>>>> insulated boom.
> >>>>>>
> >>>>>>> Billy Simpkins wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>>> Is a fiber glass or some
> other
> >>>>>>>>
> >>> non-conductive
> >>>
> >>>>>> material necessary for a
> >>>>>>
> >>>>>>>> cross boom? What or the
> >>>>>>>>
> >> advantages
> >>
> >>> and
> >>>
> >>>>>> disadvantages versus a metal one?
> >>>>>>
> >>>>>>>> Thanks,
> >>>>>>>> Billy KF0CK
> >>>>>>>>
> >>>>
> _______________________________________________
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> >>
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> >>>>>>>>
> >>>>>>>>
> >>>
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