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Re- Installing Motorised Dish

R

ronsuechris

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#1
Hello,
I had a Channel Master 1mtr Dish with Polar Mount,SMW XL-1000c LNB, IRTE Polariser, 3" stand and 18" Echostar Actuator connected to a Pace MSS 500 with Internal positioner by "Ribbon cable" out of sight, in a back yard in my "old" house.
I now own a Echostar AD3000IPVA ( which at present is connected to a 80cm fixed dish with a standard "Universal LN:cool:and wish to re-connect all the above named "gear" but it will mean the cable has to "run" through the garden.
The LNB was of "Quad" type will it be useful for a Digital set up?
Will the IRTE polariser be of any real use , I know there is a Skew setting within the Echostar Menu's
Is there an alternative to Ribbon cable , maybe a one cable solution using Diseq.
I tried searching the How to/FAQ's but was unable to get any help
any advice greatly appreciated
Ronbel
 

rolfw

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#2
Shouldn't be any problem with a single cable run if you opt for a DiseqC positioner, they are relatively inexpensive at £60 or so and will operate your larger dish. I'm not familiar with the Echostar, but I'm sure that it has DiseqC 1.2.

The Quad LNB will only be of use if it is a universal, having said that the universal you are presently using should suffice.

Rolf
 

2old4this

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#3
actually, the Echostar ad3000 does not support DiSEqC v1.2. I guess the thinking is that it doesn't need to since it has a fully integrated proper positioner.


2old
 

rolfw

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#4
Oh Well, back to the ribbon cable :(

Having said that, there is also a budget DiseqC 1.2 controller at around £50 if you really feel that you want to dispense with the extra cables.

Rolf
 

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#5
None of the new receivers on the market will support polariser systems

Ditch the Irte polariser immediately - As the frequency increases through the feedhorn, there is an inverse relation between the drive current and the amount of skew that is provided with a ferrite type system. As you scan a satellite using the set up as it is from 10.7Ghz to 12.75 Ghz you will find that the receiver will be unable to locate almost 70% of all channels available

The quad LNB requires 13/18 volts as its band switching system so you would have to disable the function in the LNB install menu when it comes to polarity switching, not easy.

It can be done and you would need to replace the polariser with a mechanical type with three wires, (this is where it starts getting expensive and difficult to track down), then slave the band voltage from another source, I use the Winersat 906 to do this and slave the signal to the digital box

Best to go get a Universal LNB that will fit directly onto the existing feedhorn of your moving dish (flange type or C120 - about £20 tops), then youre ready to go. If the feed does not come away from the Irte polariser through corrosion then soak it in WD40 for an hour or two and use mole grips on the small bolts
 

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#6
>None of the new receivers on the market will support polariser systems

I may be misunderstanding what you mean by a "polariser system" ... but there are certainly new receivers that drive polarisors - the ad3000 series being just one example!

2old
 
R

ronsuechris

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#7
Thanks to all for the ideas
Will need to "digest" them and will then deicide which way to go
cheers
 

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#8
Dear 2old

Magnetic polarisers have gone the way of the 10GHz LNB and the Chapparal Monterey in the digital age, they are guaranteed to hinder the reception of MPEG signal if connected to the system

Whilst the receiver has the ability to drive one, it is really a throwback to the old analogue days which the AD3000 can still receive. You wont find many digital only receivers that have the same connections

I still use the mechanical 3 wire polarotor as it allows the conversion of the C 120 flange to a good low noise WR 75 full band LNB and can be used to fine tune the skew settings on the weaker satellites (AMOS, Thor 2 and so on). A Universal LNB of any make just cannot compete when it comes to fine tuning. I would dearly like to have some spare time to perfect a full mechanical feed rotator on the end of the dish and eliminate the Chapparal bit, however the refridgeration of the LNB is bespoke and the fluid pipes are non- flexible past the feed support rods.

One day Ill take a course in plumbing and get it right
 

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#9
CH - if you want a single LNB that can process both circularly- and linearly-polarised signals, the receiver needs to be able to adjust the skew of the polarisor when switching between them. So in those (mainly non-European) regions that have such a mix, that feature on a receiver can be very useful. The Echostar ad3000 for example offers it, and some of Echostar's biggest markets are the regions where that is the case (Russia, Middle-East...).

2old
 

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#10
Dear 2Old

There is no correlation between the LNB and a polarisation system in a satellite system. For money saving purposes only, the domestic feed has been used to bring everything together and the end result is the Universal LNB and the dielectric plate.

Im sure you are familiar with the history of LNB technology but for the others heres a bit of education

Think back through the mists of time-

Eighteen Years ago - Ku band was a twinkling in someones eye, C band ruled with massive LNAs, separate power supplies, 1450MHz tuners, short 50 Ohm cable runs and dish sizes out of science fiction

Sixteen years ago Ku appeared. LNBs with noise figures of 2.5dB were considered state of the art. 75 Ohm cable arrives along with the first 470 MHz tuners, allowing longer runs and the F type connector. No polarisation system unless you turned the feed round on the dish. Little need as almost all satellites are one polarisation only

Fifteen years - the Mechanical polariser appeared. It was a foil accordian device that bent the signal using a crude servo. The Black Bomb appeared that gave 2dB noise figures to reduce dish size down to manageable levels of 1.8 / 2m. First motorised domestic installs under £2000 for sixteen channels (wow !)

Thirteen years ago - a split in technology

On one side - Noise figures improved with HEMT technology. Some bright spark from Racal comes up with the two wire ferrite polariser and then the dual band LNB from Sharp. 13/18 used to change bands. Chaparral mechanical three wire patented as the Polarotor.

On the other - Along came the Voltage Switching or Marconi LNB. SKY makes up plans to rule the world and capitalise on cheap outdoor equipment to remove another cost to the eventual customer. Single cable to the dish driving polarity and signal. BSB uses the single polarity for their planned satellite with circular polarisation. De polariser of PTFE inside the feed is suggested. TDF (France ) and TVSAT (Germany) are built with similar DTH/DBS specification.

Twelve years ago Sky and BSB fight with only one winner. Marconi LNB sales in one year outstrip ALL other LNB sales previously.

Ten years ago - BSKYB sells off both BSB satellties to Scandinavia for 1Million each. Sirius and Thor 1 are born and serve their respective buyers for another eight years. 2050MHz tuners make an appearance along with the full band LNB.

Eight years ago- The idea of inserting tone signals into the cable is demonstrated for purpose of switching two signals and hence two satellites from one cable. Somebody else thinks, I could use this with the 13/18 volt system for adjustment of all polarities and bands using just one cable.

Seven years - 10.60 GHz is thought of as the second Local oscillator and the Universal LNB is born. 2150 MHz tuners are brought in to give the compatibility with the LNB

Six years ago - The number of Universal LNBs sold in this year again outstrips all sales of all other types of LNB previously

And you of course know the rest.

The insertion of any depolariser dielectric is not considered in a true feed system. On all commercial systems a depolariser is a mechanical filter using segmented slots down two sides of the feed, which filter out the unwanted signal. For the other polarisation the whole feed is rotated with one component remaining static. Efficiency is maintained and the mechanical servo system is a separate drive from the indoor equipment.
I use the depolariser for both bands not through choice but through a lack of time and plumbing expertise. When its sorted, Im certain I'll add a few more low signal transponders from the ether to my viewing pleasure.
 

2old4this

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#11
Nice history, good info!

On the polarisor thing, perhaps I should have been clearer in my use of the term "LNB".

Here's my understanding of the situation:

Indeed there is no correlation between the actual LNB and a polarisation system in a satellite system. That is, the LNB itself (as distinct from the polarisor) is not in some way tailored to the incoming signal's polarisation - since it only ever has to distinguish H or V (the circular polarisation being viewed as H/V components, or else having been depolarised to H/V by a dielectric plate).

But my point was relating to the need for the polarisor to be skewable if one wants to view linearly- and circularly- polarised sigals using one "unit" (let's call it that, rather than "LNB"). If the polarisor is NOT skewable (as is the case for the fixed probes in a Universal LNB, for example) then it will not be possible to receive the circularly-polarised signals depolarised by the dielectric as well as the originally linearly-polarised signals (since with the dielectric optimally oriented, they end up at 45 degrees to each other at the polarisor).

If I am misunderstanding something, could you please make the necessary corrections/additions to the circular polarisation FAQ I wrote recently:
http://www.satellites.co.uk/scripts/webforum/DCForumID20/76.html


By the way, this (interesting) disssion arose because you stated that no new digital systems support magnetic polarisors. And you went on to state that to use one would hinder the reception of MPEG.
Can you explain what the issue there is? Why would a magnetic polarisor be a problem, but not an electro-mechanical one?

2old