Re: [amsat-dc] inquiry about homebrew az-el systems (Samudra Haque)
Thanks Pat, I'm going to have to spend a bit of time after two weeks from present to collate all the work done to date in a methodical analysis and see if there is any trend, or benefit to a particular design and what the options are for small batch kit form production.
73 de X
On Mon, Feb 25, 2013 at 2:09 PM, Pat Kilroy [email protected] wrote:
Hi Samudra,
Gosh, here are some of the oodles of plans out there for different az-el antenna pointing solutions to get you started. See below.
I'm sorry I don't have info on motor suppliers or the other items you mention. Hope these might be helpful none the less to you and others.
Cheers,
Pat Kilroy N8PK
From ANS-020 released Saturday, January 19, mainly introducing our Workshop on Portable Satellite Ground Stations, but includes buried nuggets on antennas and az-el:
Links for antenna ideas: http://arrowantennas.com/ http://www.elkantennas.com/ http://www.g6lvb.com/homebrewarrow.htm http://www.amsat.org/amsat-new/information/faqs/crow/index.php http://www.amsat.org/amsat-new/echo/Az_El_Pos.pdf http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf http://www.amsat.org/amsat-new/tools/downloads/iROTOR.pdf http://www.arrl.org/shop/The-ARRL-Satellite-Handbook/ http://ac6v.com/antprojects.htm Links for software ideas: http://www.amsat.org/amsat-new/tools/software.php http://www.amsat.org/amsat-new/tools/ http://www.moetronix.com/spectravue.htm http://www.amsat.org/amsat-new/information/faqs/resguide.pdf http://sdrsharp.com/
From ANS-048 released Saturday, February 16: http://www.vk3um.com and http://www.vk5dj.com/satellite.html and then derived:
http://www.muratamems.fi/sites/default/files/documents/sca61t_inclinometer_d... and http://www.digikey.com/product-detail/en/SCA61T-FA1H1G-1/551-1005-1-ND/75130...
The LVB Tracker Box by Howard Long, G6LVB: http://store.amsat.org/catalog/product_info.php?products_id=63
From ANS-041 released Saturday, February 9: ANS Archives http://amsat.org/pipermail/ans/
Me? I must be choosy on which wheels I re-invent, especially when I need proven/reliable operations out of a station component, such as Az-El motion. I use a heavy duty camera tripod to steer portable antennas, and I cheated and got the Yaesu G-5500 combo ($730) for portable, semi-portable and fixed operations: http://www.hamradio.com/detail.cfm?pid=H0-002765
-----Original Message----- From:[email protected] Sent: Sunday, February 24, 2013 03:00 PM To: [email protected] Subject: AMSAT-DC Digest, Vol 8, Issue 13
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Message: 1 Date: Sat, 23 Feb 2013 18:59:35 -0500 From: Samudra Haque To: " [email protected]" , Amsat-bb Subject: [amsat-dc] inquiry about homebrew az-el systems Message-ID: Content-Type: text/plain; charset=ISO-8859-1 Hi, about two years ago, I started a design for a robotics class project of a AZ-EL rotator controller system, and a hardware package for the mechanism for rotating an antenna in any direction sub! ject to mechanical stops. The system would have been able to handle regular and flip modes. I didn't do anything more than calculations, and moved on to building a classroom instructional robot then. Lately, as I am setting up (K3GWU, the George Washington University Amateur Radio Club and Research Station) I find that the price of az-el systems such as G5500 + Yaesu AZ-EL rotors are expensive, and are not typically available on an affordable basis on Ebay or eham.net etc. Well, of course, expensive is a relative term, for a student hobby organization, it's a lot, and I guess for small ham operators it is also moderately expensive. This may be a frequently asked topic: does any one have experienced with (tested) kit designs for AZ-EL rotors that can be made with parts from current suppliers ? I know there are a number of controller designs, but I am interested to know if there are any options for suppliers of the required gears/motors etc. I have located several large AC mo! tors / DC motors at my university mechanical engineering workshop, but they are not all guaranteed the same specs. I now realize if I do embark on a actual design process with my model/simulation/hardware, it would be nice to build several of these all at once to share the development cost over the production run, and ensure those who want a cheap AZ-EL system can get one. Otherwise the production cost of one heavy duty system is going to be quite high. I hope some of you may have suggestions for me, both (+) and (-) or perhaps (~) in nature. I thought amsat / amateur radio folks have a common need to encourage homebrew activity to keep their brain cells in working condition? I'm opening this question up to the national US audience, and welcome any discussion on the challenges of making the ever-so-important azimuth-elevation rotor. I've studied some of the alternatives: Alliance U100 and Yaesu G-5500. I think we can do better in 2013. But ideally, to allow the wide adoption of AMSAT ground stations, what price point would the system have to b! e to make it worth building ? 73 de N3RDX George Washington University
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Two additional points, speaking as someone who's mechanical fabrication & coding skills are equally lacking (downside of systems engineering is you understand the functional flows, associated diagrams, requirements boundaries, etc. quite well, but need a bit more than a book of "the system shall..." statements to accomplish anything!).
The WA5VJB "Cheap Yagi" designs are ridiculously easy to build [the most complex tool is a guide to keep a hand drill perpendicular if you lack a drill press]; given the relatively lower gain required for LEO satellites, it would cheap & easy to build a higher-gain version of the Arrow (I am 1/2-way there) or pairs of LHCP and RHCP antennas and switch to one or the other rather that at the phasing harness level. They are not as-is rugged enough for permanent installation, but I think the design could be adapted. There is a DK-something in Germany who has published a wealth of high-performance designs that are suitable for permanent installation if you select the right components. In emails with WA5VJB, he mentioned to me that the performance of the Arrow is very suboptimal. That's one reason why smaller (fewer elements) designs often outperform the Arrow. [Not that I dislike the Arrow, I have one & it works.] I think he's discussed this in CQ Magazine or CQ-VHF.
It is a tempting design project to acquire surplus drive motors and fabricate a mechanical system and remote/computer control (and I'm semi surprised the VHF/UHF rover community hasn't done more with this), and it is something I'd like to do myself; I'll note however that the Yaesu az/el rotor controller draws very little power - a small inverter was sufficient to run mine for Field Day last year. Further, Bob Brunginga (WA4APR) has noted that an azimuth-only station can be quite sufficient for at least getting started with LEO satellites. Something to keep in mind, depending where the resource budget falls in terms of manpower vs. money. Historically, AMSAT has opted for the people time are cheaper than dollars.
I look forward to seeing what you find out, Samudra, and hope you are able to attend the DC portable satellite meeting the end of March.
73 Steve KS1G
participants (2)
-
Samudra Haque -
Stephan Greene