Date: Sun, 5 Dec 93 04:30:33 PST
From: Ham-Space Mailing List and Newsgroup <ham-space@ucsd.edu>
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Subject: Ham-Space Digest V93 #100
To: Ham-Space
Ham-Space Digest Sun, 5 Dec 93 Volume 93 : Issue 100
Today's Topics:
Are non-metallic cross booms necessary?
Two-Line Orbital Element Set: Space Shuttle
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Date: 2 Dec 93 00:35:03 GMT
From: pitt.edu!gvls1!hpwisf1.han.paramax.com!raichel@uunet.uu.net
Subject: Are non-metallic cross booms necessary?
To: ham-space@ucsd.edu
The latest AMSAT proceadings has an artical on this subject.
The authour said that if the elements are mounted 45 degrees from the
crossboom (look like an x instead of + when look at antenna from the
front or rear), then there is NO PROBLEM with using a steel cross boom,
and running the feed lines down the boom AS LONG AS the cross boom is
not mounted at points n*1/2 wavelengths from the feed point.
He shows charts of the metal boom running 0, 45 and 90 degrees,
through the elements. At 0 and 90 degrees, there was LOTS of interfearence,
while at 45 degrees, there was very little. This is because the metal boom
is not in the same plane of EITHER of the two planes of elements.
He also shows charts saying that if the cross boom is mounted at
multiples of 1/2 wavelengths from the driven element, even if it is not
in the same plane as the elements (45 degrees), there wsa interfearance.
There was minimal interferance if the boom was mounted anywhere else.
I can't remmember the exact title of the artical, or publication
from AMSAT since I looked at a friends copy. :-) But I think that it
was the latest AMSAT meeting proceadings. Check with AMSAT.
I have a pair of KLM 22CX and 40CX Oscar antennas on a 5 foot
tripod with AZ/EX rotors on my roof. I use these antennas for both terestial
and OSCAR work since I do not have enough room for two antenna systems.
I have tried mounting the antennas at a 45 degree angle
(x VS +) configuration. I found that the x configurations performed
VERY POORLY in terestrial contacts (cross polarization?), but OK for
OSCAR use. So I am stuck with using the + configuration which performed
MUCH better for me, but REQUIRES a non conductive cross boom.
Phase II of my antenna project is to phase a PAIR of KLM 22CX and
a PAIR of KLM 40cx antennas. This requires a 11-12 foot cross boom!
Any suggestions where I can get a 1.5" or 2" 12 foot solid fiberglass
rod that can support a 20 pound antenna in 70 MPH winds over a 6 foot
unsupported span? That is why I was REALLY interested in the above artical!
My current crossboom is a 5' fiberglass rod. I cracked it
a couple of months ago when the coax from the 40cx caught on a bolt on
the tripod! I have shortened the coax, so I don't think that the problem
will happend again. But I do not know how much longer the cracked
fiberglass rod can hold out in the upcomming winter storms!
The coax
(4XL) was not damaged because I have a ground wire attached to the boom of
the antenna, and taped to the coax. Fortuantely, the 12 guage copper wire
took most of the strain, and not the N connector on the coax! (The
ground wire is there to hopefully, dissapate static charges, and hopefully
ward off lightning strikes. I have never been hit by lightning so it
must work right? :-) )
Thanks
alan
------------------------------------------------------------------------------
Name: Alan Raichel If you think the answer is simple,
Call: N3IKI then you probabaly don't understand
Inet: raichel@han.paramax.com the question.
ICBM: 39'10' N 76'30' W #include <std_disclaimer.h>
------------------------------
Date: Fri, 3 Dec 1993 17:58:42 MST
From: europa.eng.gtefsd.com!howland.reston.ans.net!vixen.cso.uiuc.edu!uwm.edu!math.ohio-state.edu!news.cyberstore.ca!nntp.cs.ubc.ca!unixg.ubc.ca!kakwa.ucs.ualberta.ca!alberta@library.ucla.edu
Subject: Two-Line Orbital Element Set: Space Shuttle
To: ham-space@ucsd.edu
The most current orbital elements from the NORAD two-line element sets are
carried on the Celestial BBS, (513) 427-0674, and are updated daily (when
possible). Documentation and tracking software are also available on this
system. As a service to the satellite user community, the most current
elements for the current shuttle mission are provided below. The Celestial
BBS may be accessed 24 hours/day at 300, 1200, 2400, 4800, or 9600 bps using
8 data bits, 1 stop bit, no parity.
Element sets (also updated daily), shuttle elements, and some documentation
and software are also available via anonymous ftp from archive.afit.af.mil
(129.92.1.66) in the directory pub/space.
HST
1 20580U 90037B 93337.23514370 .00000795 00000-0 67617-4 0 3686
2 20580 28.4689 54.6088 0004547 24.2499 335.8285 14.92945302196790
STS 61
1 22917U 93075A 93337.26873843 .00000095 00000-0 00000+0 0 52
2 22917 28.4704 54.4564 0043739 56.4750 98.8891 15.08705509 136
--
Dr TS Kelso Assistant Professor of Space Operations
tkelso@afit.af.mil Air Force Institute of Technology
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End of Ham-Space Digest V93 #100
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