Motorised skew adjustment - any ideas?

[kingkad]

Afternoon guys

Any1 have any ideas on a rig to motorise the skew adjustment on a 60mm collar LNB on my 3.8m? I want to play with the dish a lot more but changing the skew is such a job since its in the inverted position, that it just ends up fixed where it is.

Welding up a new LNB mount for the end of the feed arms is not an issue, just want to make a decent rig which allows full skew adjustment -40 to +40 without getting up a ladder and lower arms etc...

 

[RimaNTSS]

I have this obsession for long time already, but unfortunately no decent solution. Agree with you, that having some kind of servo-operated tool inside which is possible to fix C-band (60mm) or Ku-band (40mm) LNB, or combined C/Ku (60mm) LNB. I have friend, he works in university in laboratory, his hobby are robotics and radio-guided air and sea models. At his work he has very interesting computerized tools to make any out of plastic made cog-wheels etc. So, basically he said that he could produce one for me. He also made some drawing, which does not make lots of sense to me before I have something in my hands.
Please, if you find solution, share it here as well, I am still interested.

Add: And BTW ( I did not try it), but using of electrical polarizer is another option.

 

[kingkad]

This is my current idea.

1. Get an LNB with a nice uniform collar e.g

40mm


or 60mm


2. Then get 2 bearings with an internal diameter 1-2m bigger than the LNB collar and sleeve it on to the LNB. On the 60mm LNB shown this will be quite easy as the feed is detachable but on the inverto you would have to cut carefully around the end of the LNB collar near the feed, sleeve on the bearings and then stick the plastic feed cap back on.



3. The on the back of the LNB, find the centre point of the LNB on both axis. On the LNB below its marked quite nicely with a dimple (and my arrow)

Then you need to get an RC servo like below:

And glue the gold (rotating part) of the servo exactly to the centre point on the back of the LNB

4. Then you have to glue some metal rods on opposite sides (at each end of the horizontal line) of one of the bearings (the other bearing is the new collar for attaching LNB in mount)

And then attach a metal rod on the end of the triangle above which runs parallel to the LNB going to the back of the LNB. Then another metal rod on the back of the servo connecting to the parallel rod

e.g (my image in paint)


Then you just use RC controls to move the LNB with the servo however accurately you need, e.g steps of 0.5degrees for every click.

 

[RimaNTSS]

Interesting, but will not be so easy to accomplish.
Look here www.fibo-owners.com/forum/en/viewtopic.php?f=20&t=506 are lots of interesting ideas to make this.

 

[Channel Hopper]

Are you trying to achieve skew adjustment on the C band, Ku band, or both ?

 

[Trust]

If you skew the complete dish , you are free to use or change any lnb .

At the right picture the 150 cm PF attached to a gearbox to skew the dish
The left picture is a 120 cn Echostar offset attached to a brake-dish with the original wheel bearings from a rear axle (Renault)
In the middle a motor skewed KU lnb for that Echostar .
This set was made to test horizontal reception improvement with the offset dish in a 90 degree rotated position . (not any improvement)

 

[kingkad]

i just want to do it as proof of concept and to save me climbing up the dish when i want to change skew either cband or ku.

skewing a 3.8 is not feasible, easier to skew the LNB

gonna try putting together my idea on a small ku band here

 

[Channel Hopper]

A link to a Fibo site upgrade

www.fibo-box.com/polarizer.html

 

[BlindFaith]

some ideas ;)

hxxp://www.satshop24.de/satshop24_s/skew_kontroll_der_skew_kontroll_dient_zu.html

 

[Channel Hopper]

i just want to do it as proof of concept and to save me climbing up the dish when i want to change skew either cband or ku.

From my experience on site, you got others to climb the ladder

 

[7mdish]

hxxp://www.satshop24.de/satshop24_s/skew_kontroll_der_skew_kontroll_dient_zu.html

Well, photos are not so clear and I don't speak german.... Do you know if this motor can be used with any LNB or buying specific LNBs is needed? Do you know how this motor is controlled? Maybe diseqc? Thank you.

 

[RimaNTSS]

those are servo-motors

 

[7mdish]

those are servo-motors

So if I understand correctly no LNB included, right? And how to control servo motors? Maybe a common 12 volt power supply and manual switch to swap voltage polarity and moving in both direction? Could you please explain better? Thank you.

 

[BlindFaith]

Well, photos are not so clear and I don't speak german.... Do you know if this motor can be used with any LNB or buying specific LNBs is needed? Do you know how this motor is controlled? Maybe diseqc? Thank you.

It's KU-band only. The pictures show complete assemblies including:
1) LNB, PO-40 Offset Feed, servo control
2) LNB, PO-40 Offset Feed
3) LNB without feed, servo control
4) LNB only

LNB: Inverto Black Ultra TWIN LNB
no diseqc

 

[RimaNTSS]

In robotics and all flying and floating remote-controlled models they use servo-drives. Of course, you will need control unit (wired or even wireless).
http://www.seattlerobotics.org/guide/servos.html
http://www.engineersgarage.com/articles/servo-motor
and there plenty more in google

 

[7mdish]

I visited these links. So, it seems not so far from our good old Corotor feedhorn, where you must send a variable length wave for polarity fine tuning. Is it correct? If so, can I use a good old satellite receiver to control this device or a specific controller is needed? Thank you.

 

[7mdish]

As I specified in another thread, it seems that a good controller for this servo motor exists. It is manufactured by Titanium Satellite and its name is ASC1. It can drive a dish using a polar mount or H-H system, and has another 3-wire output (5V, GND, pulse) to control a polariser or this servo motor. A real test would be very very interesting. Any advice is greatly appreciated.

 

[Peyu75]

Hello
Here is my skew control
Regards

 

[RimaNTSS]

Great job Peyu75!
Motor is quiet big! How you control it? Maybe you can make short movie and post it here, very interesting!

 

[Peyu75]

he motor is powered by a 12v power supply with variable speed from home has 3 revolutions per minute may seem high but it is not the motor is enclosed in the old lnb NJR it very quiet and most importantly that it fulfills its role.
Of course, as soon as you try to make a small video of this original twist.
Regards