Servo motor polarity switching (1 Viewer)

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Andyboy90

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Aug 14, 2018
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Edmonton, Canada
i was doing some research and stumbled upon some LNBs made by Chaparral that change polarity with a servo motor attached to them. Can somebody explain how these work and the benefits of these over regular C band LNBs
 
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Titanium

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May 23, 2013
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There are several feed types available.

1. LNBF: A one piece unit that has both the feedhorn and the LNB manufactured as one unit. The LNBF can be single polarity, fixed dual polarity, band stacked (both polarities witout voltage switching) or more common to find voltage switching dual polarity. The voltage switching dual polarity LNBF electronically switches between horizontal and vertical (or circular left/right) when the receiver LNB voltage is toggled between 13 and 18Vdc. The voltage switching polarity is a simple and inexpensive method for automatic polarity switching, but it does not allow remote skew fine-tuning for signal optimization. All adjustments are universally set when installing or servicing the LNBF. Depending on the model, LNBFs can be used with single receiver or multiple receiver installations viewing both polarities on one satellite.

2. Separate Feedhorn and interchangeable LNB with servo motor polarity switching by mechanically rotating a probe inside the feedhorn. This type of feed provides polarity optimization to reject opposite polarity signals and off axis interference. Often favored by hobbyist wishing to have the most control and optimization for each satellite and polarity. Usually used with single receiver systems as only one polarity is available at one time. The servo motor requires a controller that used to be included in legacy receivers. Consumer receivers are no longer distributed with built-in servo polarity control. An interface controller can translate the receiver voltage polarity LNB power output to automatically position the servo motor probe. An example of an automatic servo controller is the Titanium ASC1. Servo controllers are also built as kits or add-ons.

3. Orthomode: Separate feedhorn and interchangeable LNBs. Each polarity requires a dedicated LNB and the polarities are fixed. Depending on the switch that is used to combine the polarities and bands, can be used with single receiver or multiple receiver installations viewing both polarities on one satellite.
 

Andyboy90

SatelliteGuys Pro
Aug 14, 2018
150
113
Edmonton, Canada
There are several feed types available.

1. LNBF: A one piece unit that has both the feedhorn and the LNB manufactured as one unit. The LNBF can be single polarity, fixed dual polarity, band stacked (both polarities witout voltage switching) or more common to find voltage switching dual polarity. The voltage switching dual polarity LNBF electronically switches between horizontal and vertical (or circular left/right) when the receiver LNB voltage is toggled between 13 and 18Vdc. The voltage switching polarity is a simple and inexpensive method for automatic polarity switching, but it does not allow remote skew fine-tuning for signal optimization. All adjustments are universally set when installing or servicing the LNBF. Depending on the model, LNBFs can be used with single receiver or multiple receiver installations viewing both polarities on one satellite.

2. Separate Feedhorn and interchangeable LNB with servo motor polarity switching by mechanically rotating a probe inside the feedhorn. This type of feed provides polarity optimization to reject opposite polarity signals and off axis interference. Often favored by hobbyist wishing to have the most control and optimization for each satellite and polarity. Usually used with single receiver systems as only one polarity is available at one time. The servo motor requires a controller that used to be included in legacy receivers. Consumer receivers are no longer distributed with built-in servo polarity control. An interface controller can translate the receiver voltage polarity LNB power output to automatically position the servo motor probe. An example of an automatic servo controller is the Titanium ASC1. Servo controllers are also built as kits or add-ons.

3. Orthomode: Separate feedhorn and interchangeable LNBs. Each polarity requires a dedicated LNB and the polarities are fixed. Depending on the switch that is used to combine the polarities and bands, can be used with single receiver or multiple receiver installations viewing both polarities on one satellite.

Thanks for the very detailed and clear explanation. If I understand correctly option 1 is for beginners and options 2 & 3 are for advanced users. So out of options 2 & 3, option 2 would be the most optimized solution (with ASC1 controller) ?
 
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Titanium

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Correct! Option 2 with the polarity servo motor provides the ability to optimize the feed on each satellite and individual polarities.

I wouldn't say the option 1 is for beginners. Many hobbyists prefer a LNBF for the simplicity, cost, ease of use, etc. :)
 

Andyboy90

SatelliteGuys Pro
Aug 14, 2018
150
113
Edmonton, Canada
Correct! Option 2 with the polarity servo motor provides the ability to optimize the feed on each satellite and individual polarities.

I wouldn't say the option 1 is for beginners. Many hobbyists prefer a LNBF for the simplicity, cost, ease of use, etc. :)

one more question. i have seen alot of different opinions on internet about this. Is there any benefit of a solid dish over a mesh? any at all?
I have seen some people mention on this forum that a 8ft solid perfoms same as a 10ft mesh. I have a hard time believing this but is there any truth in this?
 

Titanium

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It is a generalization to say a 8' solid performs like a 10' mesh. Too many factors come into play.

At 4GHz a mesh, perforation or solid sheet will all appear as a similar solid RF reflective surface.

The forming of the parabola and mechanical support accuracy are the most important factors for reflector efficiency.

A solid one piece spun or hydro formed parabola typically has the best performance. A quality build one piece composite/fiberglass reflector with carefully laid reflective material also performs very well.

Panel type reflector performance is based on the accuracy of the formed panels. Commercial panel reflectors are well reinforced and constructed to form a very accurate parabola. They usually age very well and a 30 year old reflector often performs as well as new. Consumer grade reflectors ranged from quality to crap and from small quantity regional manufacturers to mass nationally produced units.

The main weakness of many mesh panel dishes is the way the mesh is formed. Often, flat mesh panels are assembled onto frames to form the reflector. These panels roughly form an inefficient parabola. Other mesh reflectors used formed panels preassembled onto the panel frames, yielding an efficient and a more accurate parabola.

With all of this said, I would take a 8' one piece perforated spun aluminum reflector over any composite/fiberglass or panel 10' reflector any day of the week! Give me a spun aluminum 10 or 12 foot reflector and I would be in 7th heaven! :)
 

Andyboy90

SatelliteGuys Pro
Aug 14, 2018
150
113
Edmonton, Canada
It is a generalization to say a 8' solid performs like a 10' mesh. Too many factors come into play.

At 4GHz a mesh, perforation or solid sheet will all appear as a similar solid RF reflective surface.

The forming of the parabola and mechanical support accuracy are the most important factors for reflector efficiency.

A solid one piece spun or hydro formed parabola typically has the best performance. A quality build one piece composite/fiberglass reflector with carefully laid reflective material also performs very well.

Panel type reflector performance is based on the accuracy of the formed panels. Commercial panel reflectors are well reinforced and constructed to form a very accurate parabola. They usually age very well and a 30 year old reflector often performs as well as new. Consumer grade reflectors ranged from quality to crap and from small quantity regional manufacturers to mass nationally produced units.

The main weakness of many mesh panel dishes is the way the mesh is formed. Often, flat mesh panels are assembled onto frames to form the reflector. These panels roughly form an inefficient parabola. Other mesh reflectors used formed panels preassembled onto the panel frames, yielding an efficient and a more accurate parabola.

With all of this said, I would take a 8' one piece perforated spun aluminum reflector over any composite/fiberglass or panel 10' reflector any day of the week! Give me a spun aluminum 10 or 12 foot reflector and I would be in 7th heaven! :)

This has to be most detailed and most informative post I have seen on the internet about dish reflector material. Unfortunately in Canada its not viable to buy a new spun perforated aluminum dish. I dont even know if there are any local sellers and there is nothing on kijiji. The only options I have right now are tekk2000 solid 8ft galvanized steel 6 panel dish or 8ft aluminum mesh 4 panel dish. So out of these 2 the solid one should give me more performance than the mesh aluminum correct?
 

Magic Static

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There was a manufacturer just south across the border in Idaho, Andersen, but that business dried up and they just do trailer hitches now. There is a company , Vincor Ltd., They have an international number and claim to have a presence in all 50 states. They carry a full line of dishes. Antennas
 

Titanium

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Andyboy90, choosing between those two is like asking if I would buy a Ford Pinto or a Chevy Vega when a BMW Z4 is free for the taking! LOL!!!

If my only choice was a Chinese stamped steel petal dish or a Chinese aluminum mesh dish, I would reluctantly select the mesh.

Personally, I would instead pick-up a free used legacy reflector from Kijiji. So many quality dishes out there that are free for the taking! Worth the effort, time and patience in my opinion... a careful drive in the neighborhoods and countryside around you will usually yield a selection of unused dishes. If you don't see any active listing on Kijiji, post your own "Big Satellite Dish Wanted" ad.

Another source for new dishes is DTH, but the Prodelins listed in Magic Static link would be superior if you have the budget.
 

Andyboy90

SatelliteGuys Pro
Aug 14, 2018
150
113
Edmonton, Canada
Andyboy90, choosing between those two is like asking if I would buy a Ford Pinto or a Chevy Vega when a BMW Z4 is free for the taking! LOL!!!

If my only choice was a Chinese stamped steel petal dish or a Chinese aluminum mesh dish, I would reluctantly select the mesh.

Personally, I would instead pick-up a free used legacy reflector from Kijiji. So many quality dishes out there that are free for the taking! Worth the effort, time and patience in my opinion... a careful drive in the neighborhoods and countryside around you will usually yield a selection of unused dishes. If you don't see any active listing on Kijiji, post your own "Big Satellite Dish Wanted" ad.

Another source for new dishes is DTH, but the Prodelins listed in Magic Static link would be superior if you have the budget.
That was a funny reference lol!! Vincor is way out of my budget. I will take a drive down and look for old antennas on my days off. I was only leaning towards the tek2000 because with their package i got the actuator and everything needed to run a motorized dish. Not sure how beginner savy it would be easy to get the old dish running on an actuator.
 

Titanium

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May 23, 2013
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Usually an old dish just needs a good surface scrubbing, steel wool the actuator rod, lube the pivot points and lube the actuator tube. Inspect the feedhorn for wasp nest and you are likely ready to install and aim.

Legacy actuators, feedhorns, servos and LNBs are typically still working. The older gear was built to last! If the LNB is older and a higher noise figure/lower gain or drifting frequency, it is inexpensive to upgrade.

If a dish appears to be warped, damaged or the mount too corroded/rusted, don't be afraid to walk away. Plenty of fish in the sea. Don't feel obligated to take junk just because you asked the owner if it was available.

Good luck!
 

Andyboy90

SatelliteGuys Pro
Aug 14, 2018
150
113
Edmonton, Canada

primestar31

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Mar 15, 2005
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I am planning on driving down down south next week to see a friend. And Missoula is 5 hours away from his place. I will have to convince my gf for this extension to the trip lol

I'd say don't tell her at all. Just tell her that "as long as we are here, I want to take a side trip to visit a friend". Hey, you can't help it if your friend has a bunch of satellite dishes, and wants to show them off...
 
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Magic Static

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Magic Static, Didn't your friend have a 10' one piece perforated with HH mount? :biggrin
He has a 10' BirdView but it's junk :(
OldBVs 011.JPG
 
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wvman

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There was a manufacturer just south across the border in Idaho, Andersen, but that business dried up and they just do trailer hitches now. There is a company , Vincor Ltd., They have an international number and claim to have a presence in all 50 states. They carry a full line of dishes. Antennas

Vincor has a nice DH 10 foot for $969. DH quoted me a 9 foot spun for about the same money, but it came with a tuned feed. :)
 
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primestar31

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Vincor has a nice DH 10 foot for $969. DH quoted me a 9 foot spun for about the same money, but it came with a tuned feed. :)

Considering what dishes cost in the past, those prices are fantastically LOW by comparison!

For instance, a $3,500 dish back in June of 1986, would be the same as $8,054.99 today! $969 in June 1986 equals $2,230.08 today.
 
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wvman

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Considering what dishes cost in the past, those prices are fantastically LOW by comparison!

For instance, a $3,500 dish back in June of 1986, would be the same as $8,054.99 today! $969 in June 1986 equals $2,230.08 today.

I'm still amazed at the difference in buying power of the dollar today compared to 35 years ago. In 1971, I was making $5.50 an hour. I managed to pay a house payment, raise a family, put gas in my cars, go out to eat, go to the movies, pay my utilities and still had money left over at the end of the week. You tell kids that today, they can't wrap their head around it. :)
 
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