[amsat-bb] Re: Cross Boom

[MM]

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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