Satellite OASIS folding dish not ready for FTA yet...

[polgyver]

For a long time wanted to have portable Ku dish set, to show to my friends the specifics of my hobby, when visiting them. Maybe, even converting some of them to this hobby.
The e-bay offer was rather affordable.
Import charges and Pitney-Bowes brokerage added to expenses (Gee, what happened to the - so called - Free Trade??? between USA and Canada ? when I order from China, no such expenses are added... )
Anyway, the dish arrived, but it did not enable me to receive any programs, despite using PLL LNBF.
Further investigation with small mirrors and Sun light revealed that the dish focused very poorly.
Probably, with strong commercial transponders (some call them "barn-burners" ) the reception is possible,
but not with typical FTA satellites.
Annotated photos follow :

 

[. Raine]

Quite a hodge podge of reflections there! Looks neat, too bad it didn't work.

What size is it?

 

[KE4EST]

What size is it?

Polgyver, I don't think the 60cm size helps either for FTA.

 

[FaT Air]

Probably 'good enuf' for Dish or direcct.
OFF SUBJECT:
""Import charges and Pitney-Bowes brokerage added to expenses (Gee, what happened to the - so called - Free Trade??? between USA and Canada ? when I order from China, no such expenses ""
One nice racket! IMHO I was once extorted 60-70 bucks on 140 bucks worth of computer parts. Oh yeah, the extortion 'bill' arrived a week after the parts were delivered.
Call them and complain, 1 it's not obvious that there are charges, 2 if known that there are charges, the amount of those charges are not. Think I settled with UPS on the charges at 20 bucks.
Back to subject:

 

[spongella]

Like the idea of a folding dish though. A little bigger and that would be great.

Would be interesting to see, using a spectrum analyzer, the signal level of transponders with the dish.

Polygyver, how do you set up those little mirrors to assess the focal point? Are they spaced at certain intervals, and what size are they? Thanks.

 

[Cosmo Blatz]

Folding dishes! Boy, that brings back some bad memories. Years ago, I bought an 8' folding C-Band dish from Shaun Kenny. With shipping, it was around $500.00. He never shipped the dish! Never got the money from VISA. Rest in hell Shaun. Although, some say he's not really dead - just went into hiding. Anyway, the C-Band dish folded like an umbrella and the aluminum 'mesh' was I believe, similar to chainmail, the flex stuff on suits of armor. Could it work on Ku? Seems awfully ruff.

http://www.wikihow.com/Make-Chainmail

 

[bpalone]

Just a thought. How about setting up an old pizza dish using wing nuts for all the adjustment bolts and possibly the dish mounting bolts. That way it would be fairly quick to set up and knock down.

I have a Dish 500 that I am going to play with later this year. Plan on modifying the J pole so that it can be leveled easily like the J pole that comes with GeoSat Pro 90 cm dish. Was going to mount the J pole mount onto a piece of plywood, then I can just raise the J pole and attach the dish. Think it should be somewhat easy to set up and aim once it is all modified, including the mount for the lnb.

 

[polgyver]

Polgyver, I don't think the 60cm size helps either for FTA.

With all due respect, partially disagree.
For full FTA reception, bigger is better. But, for occasional demo of certain programs, 60 cm is plenty.
Providing, the dish FOCUSES properly. No "hodge podge", like it was rightly described by A. Raine.
Today I had time to do some trials of smaller dishes, a few photos follow.

 

[KE4EST]

With all due respect, partially disagree.
For full FTA reception, bigger is better. But, for occasional demo of certain programs, 60 cm is plenty.
Providing, the dish FOCUSES properly. No "hodge podge", like it was rightly described by A. Raine.

Correct I agree. I was saying the fact that the dish was on the small side and not focusing properly...it has two things going against it.

 

[polgyver]

A little bigger and that would be great.

I wish the dish could be rather more precise, not bigger...
Regarding the mirrors, they can be placed at random, no special spacing needed. Every square inch of paraboloid, by definition, should reflect to its focal point. For neat looks, some pattern could be followed. It is similar to sampling, and a very effective one. If the dish's surface is, say, 2000 to 3000 square cm, and total surface of 20 mirrors is, roughly, 20 square cm, so, the sample is less than 1 %. But it can tell a lot...
Cheers, polgyver

 

[RimaNTSS]

Like the idea of a folding dish though. A little bigger and that would be great.

I have found this folding dish (5 meters) for sale in Texas, quiet cheap and together with trailer. But it was gone too fast.
polgyver What kind of mirrors are you using? Is that tape or some kind of plates?

 

[polgyver]

What kind of mirrors are you using? Is that tape or some kind of plates?

I use glass mirrors which are typically sold at craft stores or through Internet (e-bay). These mirrors have reflective surface covered with protective grey paint. Other mirrors, like plastic or tape, are not really flat, and their reflection is not precise. Glass mirrors can be round or square - from so-called "disco" balls (these were adopted by our forum member, Jorgek). I use round mirrors, 1/2" dia, but other slightly bigger sizes can be used, of course.
Cylindrical magnet can be glued (with epoxy or contact cement) in the center of the shiny side of the glass. This lessens the force of holding the mirror to steel dish, but is more than enough to keep the mirror in place, and makes easy for the user to remove or shift the mirror on the dish's "face".
It also assures that the reflective surface stays exactly on the dish, without any "middleman" (for example, two-sided glue tape or a magnet).
When dealing with aluminum or plastic dishes, another magnet is needed on the back side of dish.
When magnet is on the mirror, the reflection has "o" - ring, or, doughnut, shape, but it is OK.
Some designs of telescopes also accept small loss of center field, when secondary mirror is there...
There is this inconvenience, that for checking dish's correctness of its geometry, we have to depend on Sun's presence.This would be unacceptable for professionals, but for amateurs, as us, is OK...
Cheers, polgyver

 

[polgyver]

For the last few days tried to receive anything from 97 W using this dish, and, finally, succeeded.
Also contacted Ian from Oasis Satellite, who confirmed, that Oasis does not recommend this folded dish for FTA.
Only Press TV and I-film were watchable at Q=23-26, other programs, like Belarus TV, Tele5 were heavily pixelating at Q=15-18
Still other programs from 97 were impossible to lock. 18" "pizza" dish was better...
Annotations on following pictures will tell more.

 

[spongella]

Excellent work polgyver, finally some success, proving that the dish can work to some extent. Just like the folks who use mini-buds for Cband work, smaller dishes present a challenge, and there are those such as you, who accept the challenge and go down the road less traveled.

Find your use of mirrors and the sun fascinating for checking dish accuracy. What is the website you use for sun azimuth/elevation?

I often wondered how manufacturers accurately (or possibly inaccurately) stamp the elevation angle markings on their dishes. Do you think they use your method?

Congratulations, and thanks for the informative pictures. You're an inspiration!

 

[bpalone]

Persistence shall persevere.

Never say die, never say quit.

Sounds like you had fun either disproving or proving that the dish could in fact receive FTA. Good job.

 

[polgyver]

What is the website you use for sun azimuth/elevation?

http://aa.usno.navy.mil/data/docs/AltAz.php (use format : degrees and minutes, not degree decimals)
What is puzzling, that undersized dishes have preference for certain transponders, and discriminate against others.
In pictures (post #8) with pizza dish, TV TRWAM had the best Q, other programs were weak.
With Oasis dish, I-FILM and Press TV were the strongest, and TV TRWAM - non existent (no lock).
Last 5 pictures :