Just Sharing This Another motorised ka band polarity project.

John

John

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This is not something new - the ease of a changing polarity mod on these stock 18 GHz Hughes broadband units was looked into some years ago by forum members Vipersan & Llew - - - This is my version of making it a motorised operation controlled from the shack.
The first part of the mod is to remove the Horizontal polarity top half of the Hughes OMT, and use the bottom 'Tx' part of the OMT as a mounting 'foot' onto the main support rail for the other components. The unused ports on the OMT being bunged with absorber and then a metal sealing plate. The OMT will now be operating as a circular to rectangular WR42 transition to suit the WR42 Norsat 18GHz pll lnb. How much of a impact on performance / mismatch of the OMT will have to be observed when final testing is done with comparisons made with un-modded 18GHz units.
The drive motor for rotating the Hughes polorizer is a low RPM 12 volt unit which is reversable and is controlled with a speed controller for added speed control.Hughes OMT - poloriser..jpg18 GHz Hughes motorised poloriser mods. - - reduced..jpg
Still waiting for some drive cogs and bits to come from China etc but here's a few pics of the project start.
 
dreamsat1

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Good and easy solution! :Y But I would have turned the LNB to get all four polarizations. :)
 
John

John

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Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
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Good and easy solution! :Y But I would have turned the LNB to get all four polarizations. :)


... that is project B after i have assessed the performance of the LHC / RHC lol.
This is the easy mod to tackle first which is as you say - the easy solution.
 
dreamsat1

dreamsat1

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OK everything good. I can help with mechanical problems and their implementation. The next unit will also be slightly different and is then suitable for heavy LNB (Norsat). Do you have a Prime Focus Antenna for KA?

regards dreamsat
 
John

John

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Location
North Nottinghamshire.
My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
OK everything good. I can help with mechanical problems and their implementation. The next unit will also be slightly different and is then suitable for heavy LNB (Norsat). Do you have a Prime Focus Antenna for KA?

regards dreamsat
... :Y:Y, i have a 1.2 'Precision' PF reflector that i use as a test dish. My main motorised Ka dish is a 1.2 Gibby that has multi band Ka lnb's on it that i change around when doing different experiments with it.
..........................................................................................................................................................................................................................................................................................................

1.2 Gibby dish cam ... reduced..jpg
 
dreamsat1

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Cool :Y My adapters and platforms all work in the Prime Focus antenna. I only have to test a 1.2m FUBA antenna.
 
Llew

Llew

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Looks to be a neat mechanical method for changing the polarity of those LNBs John. Good luck.
 
John

John

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Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
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Promax FSM.
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North Nottinghamshire.
Looks to be a neat mechanical method for changing the polarity of those LNBs John. Good luck.



Yeah, it's only a single 2 core wire connection to the micro motor Llew so is an easy install as there are some spare cables going up to the Gibby that i can use for the 12 volt motor supply. It will save me having to climb up the ladder hopefully. I'll probably build another 18GHz version with H/V/L/R capability on the same build lines as my recent Cband / Prodelin poloriser job.
 
John

John

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My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
.. done a bit more to this simple LHC / RHC motorised polarity.
Runs nice and smoothly and the speed control is working ok to get revolution speed down for fine tuning of the poloriser position.
Just got to knock up a mounting bracket for the assembly to be fixed onto the 1.2 Gibby multi-lnb changer and then do a bit of testing to see what it can do.
Next to do is the proper job on the multi polarity L/R/H/V 18 GHz lump - already started that with grafting the circ to wr42 transition onto the Norsat pll lnb along with the front rotation bearing on the lnb.
Here's a quick vid of the simple 18GHz L/R job rotating.
.................................................................................................................................................................................................................................................................................................
 
John

John

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My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
scopus

scopus

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scopus

scopus

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John

John

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Messages
2,310
Location
North Nottinghamshire.
My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
... made a start on the multi pol L/R/H/V lump today for the 18Ghz Norsat pll lnb.
Again, using stock commercial Hughes 18Ghz circular feed with stock Hughes 18GHz poloriser block through to a rotating RF coupler to a circular to wr42 transition to feed into the Norsat . Awaiting a couple of parts before continuing .
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18GHz - Norsat. L-R-V-H motorised poloriser.. reduced..jpg18GHz - Norsat. L-R-V-H motorised poloriser... - - - reduced. ... JPG.jpg18GHz - Norsat. L-R-V-H motorised poloriser...- -.. reduced. . JPG.jpg18GHz - Norsat. L-R-V-H motorised poloriser...- reduced . - - ... JPG.jpg
 
dreamsat1

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Hello John, how can you determine the exact position of the rotation? Do you have a controller and a small program that controls the whole thing remotely?:Y

best regards dreamsat
 
John

John

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Messages
2,310
Location
North Nottinghamshire.
My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
Hello John, how can you determine the exact position of the rotation? Do you have a controller and a small program that controls the whole thing remotely?:Y

best regards dreamsat
[/QUOTE



.. short answer - yes :Y.
I use a Hi Res dish cam mounted on the 1.2 Gibby Ka installation and also the 2.2 PF for Cband to keep an eye on what and where the lnb's are doing. When tuning for signals I always have my analyser running in real time as well to maximise signal reception. At the moment i am using a polarity controller from the USA / Rick's Satellite web site that controls the 3wire servo motor on the Cband installation. There is also a polarity control system i have used in the past by Pololu which uses a small servo motor module and is run on a PC program. I'll probably use a high torque 3wire servo on the 18Ghz L/R/H/V pol unit as it has proven to be quite successful on previous builds.
Here's a quick screen grab off the Gibby dish cam and also the controller , which by the way, has been placed in a more pleasing enclosure to the one that they are supplied in.

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Gibby dish cam. - reduced..jpgPol - Skew control.... reduced..JPG
 
John

John

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Messages
2,310
Location
North Nottinghamshire.
My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
** @ Dreamsat1 - - Expand above message to see my reply :Y
 
dreamsat1

dreamsat1

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My Satellite Setup
2,20m Kathrein, 3,7m Andrew, KU,KA,C,C-Ext. LNBs
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Thanks John, I have been working with Pololu for a long time and it works well. If a servo does not bring the power solo, I always use a strong engine extra. I then remove the servo board and mount a potentiometer externally. That works fine.

regards
 

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John

John

Enthusiast.
Messages
2,310
Location
North Nottinghamshire.
My Satellite Setup
Elite 2.2 PF - CM1.8 - CM1.2 - Gibertini 1.25.
Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
Thanks John, I have been working with Pololu for a long time and it works well. If a servo does not bring the power solo, I always use a strong engine extra. I then remove the servo board and mount a potentiometer externally. That works fine.

regards


Saw the Pololu board on the picture the other week and was wondering why you had put it there :Y. That sounds an interesting little mod you have done there with the board - not seen that mod done before.
Rgs.
 
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