From: Eckhard Kantz (kantz_at_wegalink.com)
Date: Sat Feb 05 2005 - 10:04:54 PST
Jim,
The same problem that you described was also encountered in my
construction with a 3m antenna. When you look at the picture of the
antenna mount:
http://wegalink.com/img/antenna_mount.jpg
there is a threaded rod visible which is loaded with several hundred
kilopond under normal weather conditions. An actuator that was mounted
in that place which was designed for 500 Kp did not stand the first
small storm. Thus I came also to the conclusion that balancing the
antenna is needed. So in spring I intend to put a counterweight which
weighed about 20 Kg to the other side of the center of rotation opposed
to the antenna. Mounted in a distance of about 80 cm the counterweight
should balance a considerable part of the antenna weight. Afterwards I
hope that the elevation actuator will be able to move the antenna again
up and down and stand all weather conditions.
Hope this could give some hints.
Eckhard
-----Ursprüngliche Nachricht-----
Von: owner-public_at_setileague.org [mailto:owner-public_at_setileague.org] Im
Auftrag von James Brown
Gesendet: Samstag, 5. Februar 2005 17:07
An: SETI League Argus; SETI League Public; Edward R. Cole
Betreff: SETI public: Re: Argus: Counterweight Idea Needed
Thanks for the information Ed. I am glad your reminded me about the
stiffness needed on the arm. I would have been tempted to make a long
arm so that I could use less weight but I can see that would be a
mistake.
Stay Tuned........ Jim
www.SETI.Net
Jim_at_SETI.Net
Argus station DM12jw
a BRIGHT
----- Original Message -----
From: Edward R. <mailto:al7eb_at_acsalaska.net> Cole
To: James Brown <mailto:jim_at_seti.net> ; SETI League Argus
<mailto:argus_at_setileague.org> ; SETI League Public
<mailto:public_at_seti1.setileague.org>
Sent: Saturday, February 05, 2005 12:17 AM
Subject: Re: Argus: Counterweight Idea Needed
Jim,
Sorry I think I misinterpreted your question.
If you are looking for mechanical designs. I have seen some amateurs
use two parallel poles with dumb-bell weights slid so you can sadjust
the balance. I another the ham used metal bucket fille diwth concrete.
My 2.5m dish is constructed with a square steel channel back frame so
the simple solution was to drill and bolt some angle iron to hold
concrete blocks which I secured with rope...crude but functional. The
antenna actually has several adjustable counterweights but I unbalanced
it when I removed the ku-band transceiver box which weighed about 40-lbs
(it was worth $500 on the surplus market).
Whatever you decide on be sure that the counterweight structure is stiff
and will not flex, otherwise the dish will bounce all over in a
wind..possibly even set up a mechanical oscillation in some conditions.
Hope that is some help.
Ed
At 05:18 PM 2/4/2005 -0800, James Brown wrote:
My SETI antenna cannot lift it's self anymore (old motors, worn bearings
etc.) and I need to add a counterweight to it. Does anyone have some
experience with a counterweight on a large antenna (12')? How is it
attached? How long is the arm? How much weight?
Thanks......... Jim
www.SETI.Net
Jim_at_SETI.Net
Argus station DM12jw
a BRIGHT
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