Primestar 84E/BSC621-2 LNBF Experiment

[satcom1]

New Pictures

Heres my current lnbf setup.

Dish motor set to 0 degrees.

Thanks for those pictures, they document very well what you have done.:up:up:up:up

It looks like you went back to the Panorama LNBF. I got two of those things and both were DOA

Did the new Scalar ring improve or about the same?

 

[brotherhood]

hi guys
i ordered 5 more but it takes about 4 to 5 weeks to come in.
would of like to ordered 10 or 15 rings but the shipping and duty charges to canada is unreal.
very nice work boys!!

 

[DREAMFOX1]

Thanks for those pictures, they document very well what you have done.:up:up:up:up

It looks like you went back to the Panorama LNBF. I got two of those things and both were DOA

Did the new Scalar ring improve or about the same?

It made channels more stable to watch.

I noticed that a lnbf with a 13 degree raiting is more stable than a lnbf with a 17 degree raiting.

I also noticed that if your dish is wide its good to set the lnbf at the correct polarity.

If you set your lnbf offset your polarity will also be offset.(Checkout the zero mark on the lnbf)

I have the lnbf set to take full advantage of my dish because its height is greater than its width.

If I put the lnbf correctly it performs poorly.

 

[DREAMFOX1]

Dreanfox1-

Use these values to double check your setup. See Screen Shots.

The protractor is very accurate and takes into account for slop and manufacturing error in Post, motor and dish. 50.42 minus 24.62 degree dish offset = 25.8 on protractor. With motor at zero.

All the SG2100 motors have a problem with the motor bracket deforming as you tighten the clamps down. Some of the brackests are made with lopsided arms. What you can do to correct this is make a rigid backer plate out of electrical box covers 4" x 4" with four holes drilled in them for the clamp rods. Then use flat washers 5/16" id X 6 at each hole. Place the washers between the bracket and the plates and double nut everything. If you need more help with that search sg2100. Stogie posted some pictures of his method.

On the dish protractor you should read the dish elevation from the screen shot at www.satsig.net 50.42 degrees. 50.42 minus 24.62 degree dish offset = 25.8 on protractor. With motor at zero.


The manual says your bracket elevation should be 56 degrees which is what your picture shows, but it is better if you use the Latitude scale on the other side of the bracket set to 34 degrees.
Your dish bracket angle should be about 24.5 degrees. But use the protractor and set the dish elevation bracket to what the protractor says. Completely disregard Declination. !sadroll

Yes, you set the pole plumb and level. but put a torpedo level across the top of the motor at the two cast lugs and check level again. Also check the back of the motor clamps for plumb.

Thanks

 

[Corrado]

I just wanted to thank Satcom1 and Dreamfox1 and everyone else here following this project for your dedication and ingenuity. I applaud this type of experimenting with C band when others simply dismiss it as a waste of time. I hope to contribute soon with some projects of my own.

(I'm trying to catch up on everything here, I was working out of state for 2 weeks.)

 

[bloomdog]

Thanks for all of the info and inspiration. I know what I will be doing this weekend...........

 

[satcom1]

Yes, I agree!

It made channels more stable to watch.

I noticed that a lnbf with a 13 degree raiting is more stable than a lnbf with a 17 degree raiting.

I also noticed that if your dish is wide its good to set the lnbf at the correct polarity.

If you set your lnbf offset your polarity will also be offset.(Checkout the zero mark on the lnbf)

I have the lnbf set to take full advantage of my dish because its height is greater than its width.

If I put the lnbf correctly it performs poorly.

DREAMFOX1-

Yes, I see what you are getting at here, It seems as though because the signal is skewed from the LNBF's perspective. By that I mean that a side mounted LNBF on a MOTORIZED dish that is using this offset signal requires a compensating offset.

Normally with a dish mover you just set the LNBF'S skew to zero and everything is great. But because you are using the dish mover to refocus the beam to the side mount LNBF, skew must be added. This is proven by your results and is not an opinion.

Another revelation that came to me about your setup is that the LNBF should be angled towards the offset beam. This is exactly what your pictures show.

So if you place a protractor at the beam center of your dish and measure to your primary LNBF, that is straight down the barrel of the LNBF. If you just side mounted an LNBF set straight towards the relative dish surface you would be canted to the offset beam. Take the string and protractor and define the focal beam from the center of the dish to the offset LNBF and you will measure; 1- How much additional motor movement in angularity you will have to add into the motor satellite setting. 2- The amount of canting you need for the LNBF. By that I mean the barrel of the LNBF should match the angel of the string so that all the energy travels stright down the LNBF waveguide. If you did not do this then the energy of the beam will be greatest at some intersection point on the waveguide tube and then reflect down the tube and not intercept the V and H probes properly. The rear portion of a C-Band LNBF is a Microwave resonant cavity. This in effest draws the wave down the tube past the V and H probes.If this is fed by a reflected wave within the tube then the LNBF will not perform at maximum efficency.

Others reading this will be confused by LNBF sidemount installations on fixed dishes looking at different satellites. This is not at all the same.

I have not seen anyone doing what you are doing here. Similar pictures seem to be on fixed dishes. Noone seems to be reporting any real success with their setups.

What I find unanswered is how you came up with this concept. Do you have an engineering background?

I finally understand the reflective nature of the offset and find that in my previous testing I was stumped by the direction of the offset wave and the direction the dish would have to move to refocus the beam on the sidemount LNBF. Now it is all clear to me and I will resume testing of your concept.

My wish is that others with a similar dish and motor will copy your setup and provide additional findings. This should be repeatable every time if one understands the elements to this design.

Finally your test of the 13K vs 17K LNBF was very interesting. The first has a gain of 55 dB and the second has a gain of almost 10 dB greater and yet the 13K performs better.

 

[satcom1]

Superdish FTA

I just wanted to thank Satcom1 and Dreamfox1 and everyone else here following this project for your dedication and ingenuity. I applaud this type of experimenting with C band when others simply dismiss it as a waste of time. I hope to contribute soon with some projects of my own.

(I'm trying to catch up on everything here, I was working out of state for 2 weeks.)

Corrado-

In another post or two people are using Superdish for FTA G18 and G27. What a great idea and it works good too.:up:up

I remember your remark about the superdish in your shed. LOL

Thanks for your continued support.

 

[DREAMFOX1]

Update on bracket holding lnbf.

 

[satcom1]

Conical Scalar

Thanks for all of the info and inspiration. I know what I will be doing this weekend...........

Bloomdog-

I hope you can repeat what Dreamfox1 is doing. I don't at this time have a true 1 meter dish or that is what I would do. The P*1M/E can't give the kind of performance that Linuxman and Dreamfox achieve.

Somehow, those two fellas need to get a true conical scalar on their projects.

 

[DREAMFOX1]

Originally Posted by satcom1

(What I find unanswered is how you came up with this concept. Do you have an engineering background?)

Answer is no, But I must of been one in my past life because I can figure out how things work and troubleshoot very quickly.

Also like to disassemble and reassemble mechanical & electronic devices.

 

[satcom1]

Motorized Offset LNBF

:::::::: NEVER FORGET, NEVER FORGIVE.

Here are some pictures describing how to determine your Offset Angle for the C-Band side mounted LNBF.

The degrees offset is used to tell the motor how far to move to focus the signal on the C-Band LNBF. So in your software you store two positions, one for KU and another for C-Band.

It also shows a "Ray" from the dish, actually the string, and how you should align the barrel of the C-Band LNBF.

 

[bloomdog]

Bloomdog-

I hope you can repeat what Dreamfox1 is doing. I don't at this time have a true 1 meter dish or that is what I would do. The P*1M/E can't give the kind of performance that Linuxman and Dreamfox achieve.

Somehow, those two fellas need to get a true conical scalar on their projects.

I will try this weekend--can't wait to try building a conical scalar. Also, just recieved a new C Band lnbf from Austria--bought it on ebay for $20.

I will photograph and post results (unless I have no success)

 

[bloomdog]

:::::::: NEVER FORGET, NEVER FORGIVE.

Here are some pictures describing how to determine your Offset Angle for the C-Band side mounted LNBF.

The degrees offset is used to tell the motor how far to move to focus the signal on the C-Band LNBF. So in your software you store two positions, one for KU and another for C-Band.

It also shows a "Ray" from the dish, actually the string, and how you should align the barrel of the C-Band LNBF.

Nice work--quick question for ya'--I have often wondered this-- do you point the side lnbfs to the center of the dish or are the front faces of all lnbfs parallel to each other? In other words, are the side lnbfs pointed so their faces are also parallel to the face (plane) of the dish? I have read that they should be parallel--that it's better that way rather than pointing the side lnbfs at the center of the dish--however, it my own experiments, I seem to have found the opposite to be true (that it IS best to aim at center of dish).

 

[satcom1]

I'm not sure!

Bloomdog-

I don't have an answer on that one, for sure. In the case of the BSC-621-2, the Ku is tucked so far back that it seems to work better if aimed at the center of the dish.

I noticed in DREAMFOX1 photos, sometimes he aims at the center and sometimes not.

I saw some pictures Linuxman had posted on a P*E with fixed mount and one lnbf seemed to be canted while the other was not.

I wasn't even sure about being able to refocus on the sidemount lnbf by moving the dish. I took a stainless steal salad bowl, in the center I put a cross made of painters tape. Then I took a paper strip and folded it into a lnbf arm and made two marks on it. One mark for primary lnbf and one for sidemount lnbf. Taped that coming out the front of the bowl. Set a led flashlight on a shelf and focused the light inside the bowl. When I tipped the bowl down a little, the cross shadow appeared on the first lnbf. I tilted the bowl to the right and the cross moved to the sidemount lnbf.

Please post pictures wether it works or not so there is record and may spure someone else in new direction.

 

[DREAMFOX1]

satcom1

You should rotate your lnbf facing your dish about 90 degrees to the left.(Fine tune if necessary)

Should see an increase in signal quality due to the width of your dish.

Also will see transponders at proper polarity.

Aiming lnbf to the center of dish improves signal for some transponders.

Not necessary if dish is wide.

 

[satcom1]

Canted LNBF

DREAMFOX1-

After last nights experiment with the salad bowl, I had confidence that I would eventually find a signal for the side mount LNBF.

I kept stepping the motor to the west and at 10 degrees west of 121 I got a KU channel BTV.

As you said, the LNBF gave the best reception at 30 degrees of skew to the west. That is proof enough for me. :up:up:up:up

Bloomdog-

On my dish the canting to the center of the dish is critical. You must have the LNBF canted towards the center of the dish.

Other findings-

Something unique to the P*E dish:

When I used the protractor to get the offset LNBF canted angle, I did not account for the dish having a built in 4 degree offset. !sadroll Add the 5 and 4 to get 9 degrees of offset and that is what worked.

What is a new finding for me, is not good news for C-Band side mounted LNBF's.

The KU (BSC621-2) signal dropped about 10% SQ and the C-Band never made it at all.
Today we have bad weather here so I will do more testing on this before I make a final judgment. :yikes

So I'm changing my opinion of this concept. On a small dish it is better to center mount the C-Band LNBF and then side mount the KU LNBF's. This will yield the best signal for C-Band on the dish and KU signals better then you can get with a BSC621-2 combo lnbf.

Conclusion:

Going back through some pictures, that is also what Andrew, implies with their center mount C-band LNBF (1.2 Meter Offset dish) and an LNBF extension arm for the 40 mm KU band LNBF's. And finally the homemade Conical Scalar ring yielded significantly better performance. So for a 1 Meter Mini Bud that should be required.

 

[DREAMFOX1]

I just noticed that my pansat 9200 Hd is not a good choice for C band.

I slaved my pansat to a Neusat HD receiver which gives me great C band reception.

 

[bloomdog]

satcom1

You should rotate your lnbf facing your dish about 90 degrees to the left.(Fine tune if necessary)

Should see an increase in signal quality due to the width of your dish.

Also will see transponders at proper polarity.

Aiming lnbf to the center of dish improves signal for some transponders.

Not necessary if dish is wide.

Please explain about rotating the lnbf 90 degrees--are you referring to the side lnbf? You lost me here, my friend...

 

[bloomdog]

DREAMFOX1-

So I'm changing my opinion of this concept. On a small dish it is better to center mount the C-Band LNBF and then side mount the KU LNBF's. This will yield the best signal for C-Band on the dish and KU signals better then you can get with a BSC621-2 combo lnbf.

Conclusion:

Going back through some pictures, that is also what Andrew, implies with their center mount C-band LNBF (1.2 Meter Offset dish) and an LNBF extension arm for the 40 mm KU band LNBF's. And finally the homemade Conical Scalar ring yielded significantly better performance. So for a 1 Meter Mini Bud that should be required.

This makes perfect sense to me, intuitively. Since obviously you get the strongest reflected signal at the center lnbf (excluding Torroidal DIshes), then the C Band lnbf would really need to be in the center for mini BUDs.