Earth-moon-earth or high orbit satellite work

chris77

chris77

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May 14, 2012
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yuba city
Hello every one, I am new to the site so let me know the right way if I do something wrong. I am wanting to get in to E.M.E or high orbit satellite work and was wondering if anyone as done something like that.
 
KE4EST

KE4EST

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:welcome to SatelliteGuys Chris!!

I have always wanted to do EME but never have. I have talked through Satellites, it has been awhile though.
 
jayn_j

jayn_j

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Sep 29, 2003
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Nothing that high. I have test equipment I worked on flying on the ISS (a couple of voltmeters and a function generator), but they weren't designed for space in particular. These days I am doing aircraft avionics and that doesn't get above 40000 ft.

My best friend, back in Colorado got laid off from Ball aerospace as a reliability engineer. He worked on Kepler and the deep impact satellites. He is now working for another space operation, but only on communication satellite stuff.

Like many, I wanted to work on deep space stuff, but lately I have been seeing the shuttle engineers coming in and doing test verification for the commercial aircraft field. Not a good time for space.

Oh yeah, welcome to satguys.
 
V

VO1ONE

SatelliteGuys Pro
Aug 13, 2004
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Hello,

Currently there are no functioning High Earth Orbit amateur radio satellites. AO-7 currently has the highest orbit, thus the best coverage. It's also a very old satellite turning 38 this year! It's a linear satellite so you must have equipment of sideband operation. It flips between two modes - Mode A which is 2 meters up and 10 meters down, and Mode B which is 70cm up and 2m down.

If you only have equipment for FM, there are currently two functioning low earth orbit satellites, not counting the space station -- AO-27 and SO-50. AO-27 repeats signals for only SEVEN minutes and only on ascending passes in the northern hemisphere. SO-50 can be used at any time that you're in the footprint. It requires PL to use and can be activated by another PL tone. AO-27 is easier because it's a stronger signal and it transmits constantly (for those 7 minutes) whereas SO-50 only transmits when a signal is being repeated through it. There's no squelch tail or courtesy tone. Full duplex capabilities are highly recommended but not required. The satellites hear really well. I work the FM sats with 1 watt into a 3 element yagi. It's more important to have good ears. A 7 element will hear down to the horizon no problem provided you don't have any obstructions. Some people use omni antennas with preamps, like turnstile antennas, but they are definitely handicapped on the receive end by doing so. Don't transmit unless you can hear the satellite! Too often I hear people transmitting away stepping on people because they're using 100 watts and can't hear the satellite! A ground plane has a null vertically from the antenna so they're even worse to use. You can build a cross yagi out of brazing rod for cheap and hook it up to an HT or better yet, two HT's for full duplex, unless you have a full duplex HT! Even off the shelf stuff you could grab an Arrow handheld yagi and a couple of those chinese monoband HTs and be active on satellite for probably $150.

FM sats are often signal reports and grid square exchanges with short QSOs. SO-50 is less utilized so you can talk longer on it. The 3AM passes you could talk to yourself for the whole 10 mintues and not hear a soul. An AO-27 transcontinental Saturday pass will be non-stop contacts almost contest style. Linear sats you can have long QSOs on since it can handle many people at one time. Of course the equipment is more expensive and it's a bit more difficult to use with a handheld antenna, but not impossible! Some have put yagis on a TV rotor at a fixed elevation of about 15 degrees with pretty good success if you don't want to go for the expense of an az-el rotator.

I've never worked EME but I'd like to give it a go. With the newer digital modes like WSJT, you can get on EME with smaller stations. If you can put out 100 watts or more into a 12 element or larger antenna on VHF or higher frequencies then you will probably be able to work the bigger stations like W5UN on 2 meters for example. When the moon is just coming up over the horizon (or setting), you can get a lot of ground gain to help the signals both ways. Do some reading and if you have the equipment, set up a schedule with one of the big stations and give it a shot!
 
chris77

chris77

Thread Starter
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May 14, 2012
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yuba city
Thanks vo1one for the info and every one else as well. It is good to know there is a chance for eme for me just have to do more research. Maybe someone can help me out on this question, can you use old dishes to broadcast your signal or no.
 
V

VO1ONE

SatelliteGuys Pro
Aug 13, 2004
177
6
can you use old dishes to broadcast your signal or no.

Yes, you can! An old C-band dish is capable of being used for EME, the bigger, the better. Mind you these are limited to probably 23cm and higher frequency amateur bands. Also, the higher the frequency, the less tolerance there is for inaccuracies in dish construction. Mesh eventually becomes practically transparent at high enough frequencies. Like LNBs for satellite television, people often use transverters mounted directly to a feed horn at the focal point of the dish due to the loss over coax cable at microwave frequencies. Commercially made equipment isn't as readily available and many homebrew their gear. The gear that is available isn't cheap. Look up Down East Microwave and Kuhne-Electronic (DB6NT) for equipment. Some are available in kit form to save some money. Also note that your typical TVRO actuator/polar mount will not suffice for EME as the moon doesn't follow the Clarke belt! I've seen people fashion these dishes to an az-el rotor often along with some UHF yagi arrays high up on a tower so they can do some terrestrial microwave work as well, but this is prime experimenters territory and there's not just one right answer.

I don't know if you plan on going to the Dayton Hamvention this year but there's going to be a VHF/UHF forum on Saturday where KA8ABR will be talking about working 10GHz EME using a BUD.
 
chris77

chris77

Thread Starter
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May 14, 2012
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yuba city
I am not going to make it this year to Dayton.:mad: I have just picked up a 8 foot dish solid aluminum in great shape and would love to experiment on it. I know it may be small, but it is a start for me.
 
chris77

chris77

Thread Starter
Member
May 14, 2012
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yuba city
I looked in to the microwave communications and would like to know what equipment I need to start out with. If anyone knows or know of links to help me out that would be much appreciated.
 
jayn_j

jayn_j

Press On Regardless
Supporting Founder
Sep 29, 2003
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BTW, I initially viewed this thread as part of a show new threads result, and didn't notice the forum. That's why my response was a non-sequitor. I thought the OP was looking to work in the industry, not ham comms.
Jay "WA9OHS"
 

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