what motor to get?

[nigel_miguel]

OK i have a 2 viewsats, and one 33 inch dish pointed at AMC 4 (for RTPi).
I'm 97W galaxy would be one I want to aim at, thus the question about the motor.
I'm thinking of adding a motor to this dish. the lnb is KU linear with dual output.

i'm trying what channels I can scan in, for fun. NOw, becuase this stationary LNB is is hooked up to two boxes. what will happen if I use for one the boxes for one sat and the other box on another sat. is the motor going to get confused? is this even possible?

if so, which motor and how do i set up?

thanks

Miguel

 

[turbosat]

Gotta let one box control the motor, don't see how it could work otherwise. Leave one dish stationary and put the motor on the other. Or you could splurge and buy two motors, make both dishes moveable!

 

[Mr Tony]

seriously...just add a 2nd LNB on the side. Then both boxes can watch EITHER 97 or 101.

I have a Primestar dish at 74 with a 2nd LNB at 79. So my 3 box4es can select 74 or 79

 

[nigel_miguel]

what kind of holder would i use for the Lnb's?

 

[Mr Tony]

most cases hose clamps (hardware stores have them)

seriously thats how about all my dual LNB (dual as in two LNB's) are set up

see pics (various examples I have had at one time or another)

 

[WSInternational]

You have to take into consideration that with a multiple LNB bracket you will have your dish fixed on two satellites and that's it. With a motor, you'll have the choice of pointing to multiple satellites.

If you don't want to mess with your dish and a motor so much and just have a fixed dish, you can try using a bracket. Check out this bracket: WS24 Multiple LNB Bracket

As for a motor, you will have to make sure you are using a DiSEqC1.2 receiver. Almost all receivers now have DiSEqC1.2, but if your receiver is about 6 years or older, I would check to make sure. :up

 

[gabshere]

what kind of signal loss is there raising the lnb up out of the dish arm factory holder to fit into the bracket holder like the WS24 Bracket? looks like its raised a 1 or 2 above the original holder. i know on homemade brackets the lnb's are placed right beside the factory lnb holder.

 

[WSInternational]

That's is an excellent question.

Believe it or not, you get zero signal loss. In fact, on a couple of the strongest transponders I noticed about a 1-3% increase in signal. See below for explanation in difference between a prime focus dish and offset dish for better understanding. In all of our testings, we used the WS9036 satellite dish along with the WS24 bracket.

Since you are moving the LNB up from the manufacturers position about 9 degrees towards the center of the dish, you also have to move the elevation of the satellite dish up about 9 degrees to make up for the adjustment of the LNB position. This will concentrate the signal more towards the center of the dish and the dish reflects it to the new position of the LNB which in return does not give you a signal loss.

For example, take a prime focus dish and an offset dish. When you see a prime focus dish and an offset dish right next to each other, pointing to the same satellite, the prime focus dish is always pointing higher than the offset dish. The reason is that the LNB is focused on the center of the dish, rather than the bottom of the dish, so the dish is pointing directly at the satellite and reflects the signal to the center and not the bottom.

On the other hand, with an offset dish, since the LNB is focused towards the bottom of the dish & not center, and since you are pointing the dish anywhere between 20-26 degrees (depending on the offset angle) below the actual location of the satellite, the signal gets bounced from the bottom of the dish and not the center. That's why your LNB is located towards th bottom... To grab the reflection of the signal.

To make a long explanation short, in order not to have signal loss and to make up for the vertical change of location of your LNB, you have to change the vertical (elevation) location of your satellite dish.

I hope this explains the answer to your question and clarifies it a bit. Please let me know if you have other questions or if I can help claify it a bit.

 

[gabshere]

thanks for taking the time to reply back and answer the question

 

[SatelliteAV]

LNBFs must be raised or lowered to be in the focal point of the reflected signal of the desired satellites. The WS24 design will perform if the install location is North of a point located between the two desired satellites. Example: Houston Texas were satellite AMC4 is located at 54.8 degrees elevation and Galaxy 25 is at 55.3 degrees elevation, a difference of .5 degrees.

Here in Sacramento, California AMC4 is located at 40.5 degrees elevation and Galaxy25 is located at 38.6 degrees elevation, a difference of 1.9 degrees. In South Florida, AMC4 is at 51.5 degrees elevation and Galaxy25 is at 54 degrees elevation, a difference of 3.5 degrees.

Placing both LNBFs at the same level will result in the reflected signal to be focused above or below the LNBF placement. This would virtually eliminate most signals due to the LNBF misalignment. If the dish does not have an adjustable skew on the rear mount, the skew angle adjustment on the bracket is critical.

Raising the LNBF above the designed focal point of the feed arm assembly does two things:
1. Reduces the signal that is reflected into the LNBF
2. Changes the elevation setting angle as the offset angle of the LNBF arm assembly is being modified
Changing the focal point of a dish does not result in zero loss or a gain as stated. This statement is false.

An offset dish is designed so the entire surface of the dish reflects signals to the designated offset focal point. Changing the focal point then adjusting the elevation setting decreases the efficiency of the reflector as reflected signals from some areas of the dish will be misdirected.

The adjustable 2 or 3 LNBF mounts that are carried by most distributors provide a great solution as they can be bent to the set the correct angle for the second satellite position and allow each LNBF to be adjusted for optimum skew.

 

[Anole]

Synopsis: I agree with SatAV

In the absence of a dish with skew in the mount, two factors permit a bracket with no elevation adjustment for either LNB to work:
1). the satellites must be near to each other
2). the satellites must be near the user's true south (his longitude)
The further apart the two target satellites are, or the closer the two satellites are to the horizon, the more an altitude adjustment will be needed on the LNBs.

Here's a case in point:
- I'm around 118°, so I'll pick two birds very close to my longitude, and 10° apart!
- 115° is elevation 50.5° . . . . (edited example birds)
- 125° is elevation 50.0°
- so for two satellites 10° apart, and near my longitude, the elevation difference is 0.5°
- probably doesn't need an elevation adjustment to the LNBs.

Now, for two birds very close to my horizon, and 10° apart!
- 53° is elevation 11.9°
- 63° is elevation 20.2°
- so for two satellites 10° apart, and near the horizon, the elevation difference is 8.3°.
- probably does need an elevation adjustment to the LNBs


The curved-track bracket is interesting.
It certainly could put the two LNBs at the same distance from the center of the dish (where the focus would be sharpest).
However, other bracket designs generally permit tilting the LNBs horizontally toward the center of the dish, and the user can tune for peak signal, if one is to be found.
Likewise, the insertion depth of the LNBs to the mounting brackets can be adjusted for peak signal.
Those two adjustments would put the LNBs on an optimally curved path.
And since that curve is determined by the particular dish, one might as well leave the tuning to the installer.

Additionally, the distance between two LNBs for tight spaced birds is a function of the dish geometry.
This problem has led to custom brackets, small feedhorn LNBs , Monoblocks, and other solutions to the popular 4° spacing problem.
edit: Given the right dish, we could probably get 127° and 129° on common every day LNBs.

Whenever I've built custom LNB-brackets, I try to keep the center of the LNB (the focal point) at the same place as original.
That maximizes signal transfer (the dish is used as designed), and it avoids that annoying error on the elevation adjustment.
I've even retuned LNB brackets, to restore the correct elevation settings to match the dish-mount markings.
Likewise, dishes with bent arms or other errors in elevation, can be aimed at a true south bird, then reset the elevation on the mount to the correct reading, and finally bend the LNB arm or LNB mount (as desired) to restore maximum signal.

Below is a drawing I found while slogging through the mud one day, showing how to measure old LNB position, and new LNB placement, when fabricating a custom LNB mount.
The goal is to keep the center of the LNB as original.

 

[WSInternational]

Here in Sacramento, California AMC4 is located at 40.5 degrees elevation and Galaxy25 is located at 38.6 degrees elevation, a difference of 1.9 degrees. In South Florida, AMC4 is at 51.5 degrees elevation and Galaxy25 is at 54 degrees elevation, a difference of 3.5 degrees.

The difference in elevation for South Florida is between about 2.3 to 2.6 degrees. ( and 2.5 degrees not 3.5 as stated above)

The difference in elevation and tilting/rotation of a dish is absolutely correct and more so if the satellites being discussed were to have more than a 2.5 degree or a dramitic difference of elevation, then that would be a different situation.

As for the two satellites being discussed, our testing and testing of the manufacturing engineers have shown that as long as the difference in elevation is no more than 2.5 degrees between the two desired satellites, the WS24 bracket can be used with no problems. However continual increase above the 2.5 degrees in the difference between the two elevations will result in gradual signal loss.

So, considering that the difference in elevation between the two satellites being discussed is anywhere between 0.3 degrees to 2.6 degrees in the United States (0.5 to 1.9 degrees in most parts of the USA) a bracket with no elevation or tilt will work great.

Actual test & example: In Marietta, GA, the elevation for G25 is 48.2 degrees and elevation of AMC4 is 46.7 degrees. That's a difference of 1.5 degrees. Using the Winegard 75cm DS2075 dish and a Tracker NA along with a DBS-3500 receiver without the WS24 bracket the signal quality for G25 11836 was about 69% to 72%. The signal quality on AMC4 11822 was 77% to 80%. Using the same LNBF and receiver as above, along with the 90cm WS9036 satellite dish and using the WS24 bracket the signal quality on 11836 was about 71% to 73% and on 11822 the signal quality was 83% to 85%

That's a very good signal strength while having an elevation difference of 1.5 degrees using a bracket, but also the size of dish aided in the increased signal quality.

 

[Wescopc]

I have installed a number of two LNBF Glory Star systems in the Northwest. For us to get an acceptable signal from both satellites (G25 & AMC4) we need to have the angle of the LNBF holder match the angle of the arc at the center of the two satellites. If it is off by even 1 degree we see degradation in the reception. It is possible to move the LNBf in/out to find the focal point of the dish and to slightlly rotate the LNBFs within the bracket - such that the polarity of each is more closely matched to the arc.

I would love to see someone design a mono-block 4 degree LNBF that would work anywhere in the US. Absent that, a dish that would accommodate two standard dual feed LNBFs with 4 degree spacing.

I have a T-90 and am able to do 4 degree spacing on it - but it is heavy and large.

I have also obtained a Big BiSat dish from France ( see: satellite antennas, satellite antenna : Visiosat )
It is a very nice dish and will do 4 degree spacing with a mini LNBF with a single feed. But will NOT accommodate a flanged dual feed LNBFs and 4 degrees.
Bob

 

[Anole]

so far off topic it deserves its own thread

I would love to see someone design a mono-block 4 degree LNBF that would work anywhere in the US.
Absent that, a dish that would accommodate two standard dual feed LNBFs with 4 degree spacing.

I just ran the numbers, and it looks like an 84e could do 2.9° spacing using the small diameter MINI LNBs.

There is some inherent error in my measurements.
Plus, I haven't tried this in all four corners of the USA.
However, it would suggest good potential for use on two birds 4° apart.

That doesn't get you both polarities.
But the Dish FSS bandstacked LNBs with the tall eliptical horns are the same width as the MINIs, so a couple of them should work.
Just a matter of a clever bracket that could rotate somewhat like the GeoSat one they use on Glorystar.

Yea, I know. It's too big 'n heavy, too.

edit:
Well, now that we've come this far, two of the narrow horned FSS LNBs on a 36" GeoSat dish, spaced as that bracket measures, should give you feed for all the receivers you want.
Assuming that is a requirement.
I meant to write this idea up a few months ago, but it was a bit too technical for the Glorystar forum department, and I figured all the FTAers here wouldn't care.

 

[SatelliteAV]

The difference in elevation for South Florida is between about 2.3 to 2.6 degrees. ( and 2.5 degrees not 3.5 as stated above)

Correct. Bad Math.... LOL!

As for the two satellites being discussed, our testing and testing of the manufacturing engineers have shown that as long as the difference in elevation is no more than 2.5 degrees between the two desired satellites, the WS24 bracket can be used with no problems. However continual increase above the 2.5 degrees in the difference between the two elevations will result in gradual signal loss.

I respectfully disagree. In our extensive testing for the development of the 4 degree rotating bracket for the Glorystar Christian Satellite System, a misplacement of even a degree will result in severe signal attenuation. Most hobbyists will be able to relate to this as they will see the Signal Quality drop if even slightly adjusting the dish aiming. Motorized dish owners can see the difference if they shift the USALS placement of the satellite in the list. One degree adjustment will reduce the quality, two and a half degrees adjustment and the signal will be gone.

Actual test & example: In Marietta, GA, the elevation for G25 is 48.2 degrees and elevation of AMC4 is 46.7 degrees. That's a difference of 1.5 degrees. Using the Winegard 75cm DS2075 dish and a Tracker NA along with a DBS-3500 receiver without the WS24 bracket the signal quality for G25 11836 was about 69% to 72%. The signal quality on AMC4 11822 was 77% to 80%. Using the same LNBF and receiver as above, along with the 90cm WS9036 satellite dish and using the WS24 bracket the signal quality on 11836 was about 71% to 73% and on 11822 the signal quality was 83% to 85%

Not an Apples to Apples comparison...... What is the SNR comparison between the single bracket and the dual bracket on the same dish. A Winegard DS-2076 dish is not 2 degree compliant, so the G25 11836 signal receives interference from G16 and degrades the performance. Since the launch of G16, most installers have moved away from using the DS-2076 as it does not reject the side lobe interference on the G25 horizontal transponders. The WS9036 appears to be 2 degree compliant and should provide significant SNR over the DS-2076 on G25 11836.

 

[Wescopc]

I should have mentioned the Star Choice 75e with a 3.8 degree, four feed mono-block LNBF. It works well in the Northwest for 4 degree 97/101 satellites, but I am told doesn't work well in other corners of the US. Also they are expensive and hard to get in quantity.
Bob

 

[cracklincrotch]

I'm in Nova Scotia and it works fine here for SC (of course) and I'm using one now for G18/G13.

Since NS is in the same latitude range of Northern New England, it should definitely work at that corner too.

 

[Mr Tony]

I use to use the SC 75e dish for 97/101 with no issues