[amsat-bb] Re: Cross Boom

23 Apr 2009

      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@pacbell.net wrote:
...
From: Jim Jerzycke kq6ea@pacbell.net
Subject: [amsat-bb] Re: Cross Boom
To: "Jeff Yanko" wb3jfs@cox.net, "Joe" nss@mwt.net, "Billy Simpkins" bsimpkins31@dishmail.net, "Edward Cole" kl7uw@acsalaska.net
Cc: amsat-bb@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@acsalaska.net wrote:
...
From: Edward Cole kl7uw@acsalaska.net
Subject: Re: [amsat-bb] Re: Cross Boom
To: "Jeff Yanko" wb3jfs@cox.net,
kq6ea@pacbell.net, "Joe" nss@mwt.net,
"Billy Simpkins" bsimpkins31@dishmail.net
...
Cc: amsat-bb@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@pacbell.net
...
To: "Joe" nss@mwt.net;
"Billy
...
Simpkins" bsimpkins31@dishmail.net;
"Jeff
...
...
Yanko" wb3jfs@cox.net
Cc: amsat-bb@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@cox.net wrote:
...
...
...
From: Jeff Yanko wb3jfs@cox.net
Subject: [amsat-bb] Re: Cross Boom
To: "Joe" nss@mwt.net,
"Billy Simpkins"
bsimpkins31@dishmail.net
...
...
...
...
Cc: amsat-bb@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@mwt.net
...
...
...
...
To: "Billy Simpkins"
bsimpkins31@dishmail.net
Cc: amsat-bb@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
...

...
...
...
>Sent via AMSAT-BB@amsat.org.
Opinions
...
expressed are
...
...
...
those of the author.
...
>Not an AMSAT-NA member? Join now
to
...
support the
...
...
...
amateur satellite program!
...
>Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
...
...
...
...
...
>
>
>
>

...
...
...
...
Sent via AMSAT-BB@amsat.org.
Opinions
...
expressed are
...
...
...
those of the author.
...
Not an AMSAT-NA member? Join now to
support the
...
...
...
amateur satellite program!
...
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
...
...
...
...
...

...
...
...
Sent via AMSAT-BB@amsat.org. Opinions
expressed are those
...
...
...
of the author.
Not an AMSAT-NA member? Join now to
support
...
the amateur
...
...
...
satellite program!
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
...
...
...

Sent via AMSAT-BB@amsat.org. Opinions expressed
are
...
those of the author.
...
Not an AMSAT-NA member? Join now to support the
amateur
...
satellite program!
...
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb

Sent via AMSAT-BB@amsat.org. Opinions expressed are those
of the author.
Not an AMSAT-NA member? Join now to support the amateur
satellite program!
Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb

[amsat-bb] Re: Cross Boom

MM