Motorised skew

[7mdish]

I'm looking for a good way to solve skewing problem in AZ/EL motorised installations.
There is an old thread in this forum, dated 2014, in which I posted some comment mentioning Viking motorised feed. It seems the only device available to solve this issue in a good way, but it costs so much! Anyone has advices about newer devices not so expensive? My goal is rotate the LNB to perfectly adjust skewing without any signal loss due to polarity errors. Thanks.

 

[s-band]

This is how I do it on an upside down Prodelin offset dish using a radio control servo and a Polulu servo controller Pololu - Maestro USB Servo Controllers. The picture shows the modified SMW LNB used for extended Ku band (up to 13.7GHz)

I've used this for a few Ku & Ka feed/LNB combinations. A few other members have also used RC servos. @John @dx qwer

I still have this

For Sale - Visiosat ku rotating feed

Great for getting the last bit of s/n by optimising the skew. As here: https://www.satellites.co.uk/forums/threads/visiosat-ku-rotating-feed.172488/ Should work with RC2000 fitted with servo board or a cheap servo driver from Ebay £60 + post

satellites.co.uk

but it is for an offset dish

 

[7mdish]

Interesting! I do not know the brand Visiosat, looking for it now.
But I would prefer some prime focus dish for my new installation. Offset is a little bit trickier I'm afraid. SSS sells some interesting and complete motorised systems with offset dishes (Raven 1.8m and 2.4m), but I'm not sure using such dishes would be possible to reach extreme Eas/West satellite positions. Probably prime focus dishes are better for such goal, as I mentioned in the other thread just below. But main issue is making a perfect skew. No problem about controller, I want to use RC2000a with polarity drive installed, the problem is the feed! Thank you.

 

[7mdish]

This is how I do it on an upside down Prodelin offset dish using a radio control servo and a Polulu servo controller Pololu - Maestro USB Servo Controllers. The picture shows the modified SMW LNB used for extended Ku band (up to 13.7GHz)

I've used this for a few Ku & Ka feed/LNB combinations. A few other members have also used RC servos. @John @dx qwer

I still have this

For Sale - Visiosat ku rotating feed

Great for getting the last bit of s/n by optimising the skew. As here: https://www.satellites.co.uk/forums/threads/visiosat-ku-rotating-feed.172488/ Should work with RC2000 fitted with servo board or a cheap servo driver from Ebay £60 + post

satellites.co.uk

but it is for an offset dishS

S-band, what do you receive in 13 GHz band? Which satellites?

 

[moonbase]

...But I would prefer some prime focus dish for my new installation....

Commercial solutions for motorised skew on a prime focus dish can be expensive.
I have attached a picture below of a motorised skew assembly that came from a 2.8m Precision Antenna prime focus dish and was controlled by an RC2000 unit.

One point to note is that motorised skew systems like the one pictured below can be heavy and some type of rim mounting or support system might be required to prevent distortion of the dish.

.

 

[s-band]

S-band, what do you receive in 13 GHz band? Which satellites?

Amos 17, but there's been nothing visible from UK and I've not seen any reports from elsewhere
Turksat 5A, There's a single test transmission and were lots of test signals a few weeks ago
USA-139 (Mentor/Orion class milsat) 13.1-13.6GHz looks like OQPSK or something like it

 

[7mdish]

Amos 17, but there's been nothing visible from UK and I've not seen any reports from elsewhere
Turksat 5A, There's a single test transmission and were lots of test signals a few weeks ago
USA-139 (Mentor/Orion class milsat) 13.1-13.6GHz looks like OQPSK or something like it

I did not know about this new frequencies. Could you please explain the LNB configuration? Not sure if one single Ku band would be enough, how can it be switched in this new band?

 

[a33]

I'm looking for a good way to solve skewing problem in AZ/EL motorised installations.

Not sure why exactly you want elevation control, but did you consider polar mount with elevation control instead of motorized Az/El mount?

That way your skew would be (about) right automatically...

Greetz,
A33

 

[s-band]

I did not know about this new frequencies. Could you please explain the LNB configuration? Not sure if one single Ku band would be enough, how can it be switched in this new band?

I took a 12.25-12.75GHz LNB and tweaked it so that the response >13GHz improved. It's not fantastic but works well enough. With the 11.3GHz LO the highest frequency on a TBS69x3 card is 13.75GHz but it does go a bit higher. I don't know of an LNB that covers the whole range 10.7-13.65 It would need a bit of work to avoid spurious responses and probably be expensive. @moonbase had some extended Ku LNBs which are described somewhere on this forum.

The Prodelin dish design makes it very easy to swap electronics and feed assemblies so that's how I change bands. I have S band through to 32GHz heads for it. For your large dish it would be harder. Have a look around the forum for LNB changers that @Trust and others have done.

 

[7mdish]

Not sure why exactly you want elevation control, but did you consider polar mount with elevation control instead of motorized Az/El mount?

That way your skew would be (about) right automatically...

Greetz,
A33

A33, yes you are right. I'm looking for AZ/EL mount due to inclined orbit satellite tracking, but as you said a good polar mount with elevation correction could be fine.​

For example, this could be a good solution:

Satellite dishes with inclined orbit polar mount motors. Raven 2.4m motorised inclined orbit satellite dishes. Dual axis, 2 motor polar mounts. UK.

Satellite dishes with inclined orbit polar mount motors. Raven 2.4m motorised inclined orbit satellite dishes. Dual axis 2 motor polar mounts. UK. 36 volt inclined orbit motors. Satellite Superstore UK. Channel Master, Andrews, Satellite dish motors. Inclined orbit motors, Inclined orbit polar...

www.satellitesuperstore.co.uk

Or this:

Satellite dishes with inclined orbit polar mount motors. Raven 1.8m motorised inclined orbit satellite dishes. Dual axis, 2 motor polar mounts. UK.

Satellite dishes with inclined orbit polar mount motors. Raven 1.8m motorised inclined orbit satellite dishes. Dual axis 2 motor polar mounts. UK. 36 volt inclined orbit motors. Satellite Superstore UK. Channel Master, Andrews, Satellite dish motors. Inclined orbit motors, Inclined orbit polar...

www.satellitesuperstore.co.uk

But, you said: "That way your skew would be (about) right automatically..." About. Yes, about! So, this is the main issue. Going to East or West limits in the Clarke belt, every polar mounts perform some mechanical errors, so the skew will never be really exact, and this could become a problem particularly getting feeds or weak signals. This is the reason for which I would prefer a motorised feed.
Also, both dishes in the links above are offset antennas. What do you think about the usage of such dishes to get extreme East/West satellites? Is it the same like a prime focus one? I'm afraid it is not.
Also, I need Quatro LNB instead of single out LNB. Do you think that LNBs offered in those bundles are OK? Thank you for your advice.

 

[Channel Hopper]

Offset dishes back on the menu.

 

[7mdish]

Offset dishes back on the menu.

Sorry Channel Hopper, I did not understand your reply (my english is very poor, sorry). Are you telling me that offset dishes are worst than prime focus for my purpose? Not sure.... could you please clarify to me? Thanks.