Just Sharing This Coming soon - - Ex Viasat Ku Motorised Pol/Skew

[John]

Winter project
Convert an Ex Viasat Ku band motorised Pol/Skew unit.
Remove existing Viasat scalar feed, convert to using Channel Master Off-set scalar and adapt the Viasat unit to fit onto the existing CM feed holder, plus - incorporate into the mod the adjusted feed positioning for the 1.2 or the 1.8 off-set Channel Master dishes provided data by RimaNTSC.
1st pic shows progress slightly into the mod - the whole build story to follow.
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[John]

So, a bit of background ....
The donor motorised Ku feed is from an ex Visiosat system which i obtained from our forum friend 's-band' and was surplus to his requirements.
The receiving dish to have the modded feed fitted apon is a high roof mounted Channel Master 1.2mtr with an upside arc view of 71East to 71West but the downside is it only has access via roof crawler so is difficult to do any serious or complex modding in situ... see pics.
I have at ground level an identical Channel Master 1.2mtr on a test rig so it's possible to set up the new adjusted feed position using a temp measurements template to assist in the fabrication of additional metalwork . The whole idea for simplicity of installation onto the tricky roof mounted CM is just to have to un-screw the two 6mm screws that hold the top half of the original feed holder and then place the modded top half of the feed holder in it's place and tighten up the two 6mm allen key type screws.
The initial alignment for modded adjusted boresight pointing will have been pre-done on the identical ground test rig - optimum fine tune for FP etc will be via signal meter at dish position via the simple adjustments built into the fabrication. The motorised pol/skew will be via a simple Left/Right 12volt motor controller pcb built into a little 'hobby' box with Left / Right push buttons. The standard 10K position indicator pot within the unit will just have a simple ohm meter readout in the shack to tell me it's H/V position as well as observing the signals on a Promax meter.
The high roof CM 1.2mtr is also visually monitored via a roof dish cam which is able to see visually the position of the SMW PLL Ku lnb in use.
A few more pics ...
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[John]

.. This is the finished motor lump holder - this will get swapped onto the roof mounted CM-1.2mtr as is and then the motor lump will be slotted into it with it's four fixing screws and then final tweeks.
The triangular side plates are from a local hardware shop that i spotted a while back and decided that they could come in handy for something at some time, same with the slotted metal bits, they are cut off some slotted right angle brackets from ebay etc.
Also shown is the SMW PLL lnb that will be used on the rig.
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[Channel Hopper]

One can never have too much surplus bracketry.

 

[moonbase]

@John

Excellent stuff !
Quick question if I may, how sensitive is the controller for fine resolution of the skew?

 

[John]

@John

Excellent stuff !
Quick question if I may, how sensitive is the controller for fine resolution of the skew?

Very MB, I'll rig the lump up on the bench and do a vid later.
Motor is rated at 12volts x 5 rpm but if you reduce the supply voltage a tad to it it is very slow to turn.

 

[John]

@John

Excellent stuff !
Quick question if I may, how sensitive is the controller for fine resolution of the skew?

Quick vid showing rotation speed etc... First with 12v and then reduced down to 7v, probably would rotate still at 6v

 

[moonbase]

Quick vid showing rotation speed etc... First with 12v and then reduced down to 7v, probably would rotate still at 6v

@John

Thanks for sharing the video.
The rotation looks nice and smooth and when the voltage is toned down it looks as though it has excellent fine tune. Well done !

Next video I assume might be the Promax on a signal showing variance with skew adjustment?

 

[John]

@John

Thanks for sharing the video.
The rotation looks nice and smooth and when the voltage is toned down it looks as though it has excellent fine tune. Well done !

Next video I assume might be the Promax on a signal showing variance with skew adjustment?

The weather needs to warm up a bit MB before i get scrambling a bit on that roof crawler, think the next bit will be checking the dish illumination accuracy of the modified feed set-up with the laser pointer fixed to the inside of the CM scalar and put it on 'rotate' .
There's a video on the forum somewhere of the illumination tracking before the feed position alteration and then after when i did a similar mod on a CM 1.8mtr i have - it's a bit of an eye opener.

 

[John]

Here's a bit more of the bracketry bits and bobs - these brackets incorporate the 'shift' required to satisfy the new feed position dictated by Rimants data sheet.
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[Manikm909]

Quick vid showing rotation speed etc... First with 12v and then reduced down to 7v, probably would rotate still at 6v

tremendous!! well done.

 

[John]

... another part of the build was to remove the main drive cog off the Visiosat scalar and transplant it onto the Channel master scaler.
There was a resulting gap to take care of which meant centering the drive cog on the CM scalar, applying adhesive and hot glue filler plus two permanent 'clamps' to firmly hold the cog in place.
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[Manikm909]

So @John - when are you going to start mass producing these and selling them on here for £10 ?

 

[John]

So @John - when are you going to start mass producing these and selling them on here for £10 ?

Lol ... main problem is getting a supply of ex-motorised pol units, i was lucky to have spotted this one some time ago when our forum friend 's-band' had no further use for it and i thought hmmmm, that could come in useful some day for something and so put in a cupboard for many months.... then saw recently our forum friends scopus/moonbase/s-band doing some evaluation work on some SMW PLL lnb's that they had and that triggered it all off - thought, i'll have some of that and use the Visiosat motorised Pol/Skew unit that's sat in the cupboard doing 'nowt.
It was a relatively easy mod really, as the CM scalar fitted perfectly inside the front housing, apart from the oversized main cog wheel, and i just had to make up a 'shim' for the rear adapter of the CM feed out of a strip of stainless steel from a jubilee clip . Having the identical CM 1.2mtr dish as the roof mounted one, sat on a test rig at ground level, along with nice supplies of bits of metalwork bracketry from B&Q / Boyes / Ebay etc made the other part of the mod easy

 

[moonbase]

Lol ... main problem is getting a supply of ex-motorised pol units, i was lucky to have spotted this one some time ago when our forum friend 's-band' had no further use for it and i thought hmmmm, that could come in useful some day for something and so put in a cupboard for many months.... then saw recently our forum friends scopus/moonbase/s-band doing some evaluation work on some SMW PLL lnb's that they had and that triggered it all off - thought, i'll have some of that and use the Visiosat motorised Pol/Skew unit that's sat in the cupboard doing 'nowt.
It was a relatively easy mod really, as the CM scalar fitted perfectly inside the front housing, apart from the oversized main cog wheel, and i just had to make up a 'shim' for the rear adapter of the CM feed out of a strip of stainless steel from a jubilee clip . Having the identical CM 1.2mtr dish as the roof mounted one, sat on a test rig at ground level, along with nice supplies of bits of metalwork bracketry from B&Q / Boyes / Ebay etc made the other part of the mod easy

It's a nice mod, the cog shims are a real treat and it looks a decent metal cog, not the plastic cogs you see in some actuators and H-H motors.

 

[John]

I knocked up a scalar ring position adjuster some time ago on my 2.2mtr PF C-band rig for fine remote tweaking from the shack and used one of these cheap 12v DC motor controllers with speed control from off the 'Bay and mounted it in a metal 'hobby' box - I can now use this to also rotate / speed control the Ku Pol/Skew modded feed on the 1.2mtr CM.
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[John]

Dish illumination / tracking accuracy set-up test - 99.9% accurate, to squeeze the last drop of performance out of the 1.2 dish & obtain this accuracy and still maintain precise new lnb pointing angles / FP etc is a pain and will have to be done again once it gets re-installed on the roof mount CM 1.2mtr - the very very slightest movement of the unit throws the tracking out - 'suppose i could always swap out to a standard 1.5mtr install to achieve the same signal levels and do away with the obsession for maximum efficiency from an installation but there's no fun in that - this way keeps the brain active in these crap troubled times.
I might re do the vid when it gets darker outside but you can see the laser dot reasonably ok in this vid. Laser starts at the bottom of the dish.
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[s-band]

Dish illumination / tracking accuracy set-up test - 99.9% accurate

Very impressive

 

[moonbase]

Very impressive

+1
Awesome illumination test of the dish by laser tracking.
Hobby dx'ing at its very best.

 

[Manikm909]

i was expecting the middle of the dish to fall away and just leave a rim!

VERY IMPRESSIVE - @John