97W & 101W in Hawaii

[jags1]

I'm working on putting together a system for use in Hawaii (96704). Planing to purchase a Fortec FS6P 180cm (6ft.) prime focus dish. The main bird I'm looking at will be the 97w (Galaxy 19) for the Thai channels however I also have A Directv receiver that I would like to use for the 101w bird. I'm planning on getting the Invacom QPF-031 with the AF-120 feedhorn so that I can do both linear and circular thus both FTA and DSS Directv.

Now here's the question. Because of my location the look angles for the 97w are 24.9 ele. and 103.2 azi. The 101w is 21.0 ele. and 101.1 azi. The difference is only about 2 degrees. With such a small difference in look angle can I get by with doing a stationary mount with cheating the dish look angle to be somewhere between the two? Or will I have to motorize the system to move the dish to these exact angles? Will this 6 foot dish be able to boost the signal here in Hawaii enough so that I can cheat on the angles? Especially the Directv signal as that is stronger than the FTA signal.

I was originally thinking of getting a seperate circular DSS LNBF for the Directv and just hang it off the side if the main FTA LNBF, but, because the look angle only has a 2 degrees difference, I don't think I would be able to get the Directv LNBF close enough to the focal point.

What are your ideas and suggestions? Any help or discussion will be appreciated!!

Eric.

 

[pedrogarcia]

Hi Jags > A really interesting question. I have tried getting 2 birds 2 degrees apart using a prime focus 2.7m dish and it was possible by mounting the 2LNB on the stonger signal on the lnb support arm and using effectively a section of the dish that has its own focal point. the dish size on the second LNB is considerably less and it can really only be done using a spectrum Analyser.
I would have thought a 6ft dish over large perhaps the real answer would be to have 2 1.2M or 1M dishes as the footprints seem to suggest But I would bow to local knowledge on size.

 

[jags1]

pedrogarcia,

Thanks for the sugestions. I tried putting two LNBF's side by side for 97 and 101 back in California on a smaler dish but couldn't get them close enogh even there where I had a bit wider of a look angle difference. It seems that when you have 2 LNBF's touching each other side by side you get a 4 degree seperation so, if the 2 satellites you are aiming at have look angles closer than 4 degrees, I don't think it will work.

As far as using 2 smaller dishes is concerned, it is cheaper to ship to Hawaii a 6 foot dish that breaks down into a smaller box than a 4 foot dish. Plus it should guarantee me a lot better signal!

I hope someone else out there has some ideas about this set up. Let me know! Thanks!!

Eric

 

[SatelliteAV]

97W in Kona is at magnetic Azimuth 90.9 degrees and Elevation 20.9
101W is at magnetic Azimuth 92.7 degrees and Elevation 24.8. The distance between the offset LNBFs will be greater. While the AZ is less than 2 degrees, the elevation difference is nearly 4 degrees (example A2 + B2 = C2).

A 1.2M or 1.8M dish is not required to receive G19 or AMC4 in Hawaii, but the extra gain will provide a better threshold during extreme weather conditions. You are not cheating on the angles, only receiving the reflected signals by placing the LNBFs in the proper position. Glorystar has sold many systems in Hawaii with the offset 90cm dish, adjustable LNBF mount and GEOSATpro SL1 or SL2. A larger dish will have a FD which should allow a small LNBF like the SL1 or SL2 to be used for 97W and the Invacom QPH031 for 101W. This might not be possible using two regular LNBFs with the larger scalers.

Several other members should be able to assist with calculating the distance and placement of the LNBFs based on your dish choice. You might determine that two regular size LNBFs can be used for your project.

I am not sure what size dish is necessary for 101w DirecTV in your region, but if DirecTV does not require the larger dish you might also consider 2 - 90cm or 1.2M dishes shipped in one carton and dedicate 1 dish for each satellite. Shipping two dishes in a single carton shouldn't cost any more than a single dish in a carton.

NOTE: Mounting the LNBFs on a Prime Focus dish may be more difficult than on an offset due to the design of the LNB mount on the Prime Focus.

 

[jags1]

Brian,

I was planning to point the dish at G19 at 97W and use a prime focus linear lnbf to pick up the FTA Thai channels from G19. Being that the FTA signal is weaker than the dirctv signals from their 101W bird it would seem better to make maximum use of the dish size and have it pointed and aligned directly with G19 for FTA.

The directv LNBF would then be offset to point at the directv 101W bird. The thing is I'm not sure if I will be able to get the dirctv LNBF close enough to the focal point because of the small angle difference between the 2 birds. I really like the idea behind the GEOSATpro SL1 as it may be small enough to get the proper angle. The problem is the LNBF I plan to offset needs to be circular for the directv signal but the GEOSATpro SL1 is a linear LNBF. Do they make those mini LNBF in a circular model?

My idea behind using the Invacom QPH031 was that since it has both linear and circular capabilities I could use it for both birds. My question is if I line the dish up with the G19 at 97W will the stronger signal of the directv bird at 101W and the large dish size give me enough signal that it would still be there even if the dish is off by a few degrees? Back in Los Angeles I can move my directv dish quite a bit and it still will pick up the signal. I'm thinking if this big dish is off by a few degrees for the directv signal it may still provide enough of a signal to work.

I hope I have explained myself a bit better and I hope I can get some more input on my theory. Thanks!

Eric

 

[Anole]

multi-LNBs, revisited:

Below are the calculations to figure out how far apart (and where to locate) multiple LNBs on one dish.
You have better results if...
- the birds are close, but not too close to each other...
- the dish has a relatively longer focal length
- the LNBS are small
- the two satellites are near zenith for you (overhead, as opposed to near the horizon)
- you are closer to the equator
I think those are all the things that make it easier, but run the calculations and see.

MJflash and his math to put two LNBs on a single dish:
http://www.satelliteguys.us/free-air-fta-discussion/89049-offset-lnbs-theory-practice.html

Every few months over the last several years, I've brought up these calculations, and even run through them for some of the members.
If you'll pick some of the related key words and do an Advanced Search including my name, I'm sure you'll uncover some helpful threads.

Here is one; see page 4 and 5 of the AMC 21 thread.
AMC 21 thread, page five, assorted LNB measurements
http://www.satelliteguys.us/free-air-fta-discussion/150263-amc-21-a-5.html

See also this thread, for info on trimming LNBs to fit, when they are too large!
WescoPC and 2° birds on a 1.2m dish:
http://www.satelliteguys.us/free-air-fta-discussion/151258-building-1-2-meter-dish-2-spacing.html

And as a last thought, if you use a prime focus dish, make sure your LNBs match the F/D, for maximum performance.
Otherwise, the typical Ku LNBs designed for 3' offset dishes, will only see the middle of your dish, and not all the way to the edge, wasting your money.

 

[SatelliteAV]

Sorry, if I was unclear in my suggestion. If the LNBF spacing will not allow two regular LNBFs with the standard scalers, use a SL1 or SL2 for 97W bird and the Invacom QPH-031 for 101W birds to allow reception of linear FSS and circular DSS signals in that orbital slot. The SL1 and SL2 are only available as linear LNBFs and would not be suitable for your 101W plans.

The 1.8M prime focus dish is overkill for either 97W or 101W FSS birds. A 1.2M dish should provide more than reliable FSS reception in Kona, Hawaii. The larger size is not necessary. Use the information provided by Anole to determine the LNBFs postitions for the dishes that you are considering to purchase. Gain is not the issue as there is more than plenty of signal in your region and you do not need a larger dish to facilitate the second LNBF. In fact, a 85 or 90cm dish will provide adequate gain, but the focal length probably will be to short to allow the LNBFs to be mounted close enough to allow reception of the 97W and 101W satellites. Your only consideration will be the focal length of the dish and corresponding placement of the LNBFs.

Brian,

I was planning to point the dish at G19 at 97W and use a prime focus linear lnbf to pick up the FTA Thai channels from G19. Being that the FTA signal is weaker than the dirctv signals from their 101W bird it would seem better to make maximum use of the dish size and have it pointed and aligned directly with G19 for FTA.

The directv LNBF would then be offset to point at the directv 101W bird. The thing is I'm not sure if I will be able to get the dirctv LNBF close enough to the focal point because of the small angle difference between the 2 birds. I really like the idea behind the GEOSATpro SL1 as it may be small enough to get the proper angle. The problem is the LNBF I plan to offset needs to be circular for the directv signal but the GEOSATpro SL1 is a linear LNBF. Do they make those mini LNBF in a circular model?

My idea behind using the Invacom QPH031 was that since it has both linear and circular capabilities I could use it for both birds. My question is if I line the dish up with the G19 at 97W will the stronger signal of the directv bird at 101W and the large dish size give me enough signal that it would still be there even if the dish is off by a few degrees? Back in Los Angeles I can move my directv dish quite a bit and it still will pick up the signal. I'm thinking if this big dish is off by a few degrees for the directv signal it may still provide enough of a signal to work.

I hope I have explained myself a bit better and I hope I can get some more input on my theory. Thanks!

Eric

 

[jags1]

Thanks for all the suggestions everyone! This morning I worked out my theories using my CAD program to draw out the focus length and the 2 angle differences in elevation and azimuth. I came up with a 25mm spacing for the 2.1 degree azimuth difference and a 47mm spacing for the 3.9 degree elevation diference. When I pluged in the numbers into the formulas you provided I came up with the same numbers! Great!! Looks like I'm on track with my spacing and it looks like I will just be able to get the 2 LNBFs in the right position if I mount them just touching each other.

Here is a drawing I made of how it will look. Using a Sadoun Collar II for C Band Dish which has a cutout on one side I should be able to get the 2 LNBFS next to each other with a drop of 47mm and a east shift of 25mm for the offset LNBF. This should be correct as I understand the offset LNBF has to be on the opposite side of where the satellite is in the sky. The offset satellite (101W) being higher and to the west. The circles represent the 40mm LNBF throat.

Now my other theory was to use the combination Circular/linear Invacom QPF031 and have the dish pointed between the two calculated positions so that it would be able to pick up both birds at the same time. The thing is it would be "off center" to either bird by about 2 degrees. The question is would this adversly effect the signal strenth enough that I would have no reception? Or would the size of the dish compensate for the loss created by the 2 degree miss alignment? Any ideas on this theory?

I"m pretty sure theory 1 using two LNBFs with the stronger directv LNBF offset will work. Do you think theory 2 using the combo LNBF centered between the 2 focal points would work? Also, I know using a 180cm dish is overkill but I feel alot better using the big dish especially considering this strange set-up and the fact that we do have a lot of rain here. Also my set-up back in L.A. theoretically is optimum for that location but I still have drop-outs on the 97W especially on the DMC channel which seems to be on a weeker transponder. My fiancee really gets upset when she loses her DMC channel and I don't want that to happen here in Hawaii with this setup!

Let me know! And thanks to all once again!

Eric

 

[Mr Tony]

Now my other theory was to use the combination Circular/linear Invacom QPF031 and have the dish pointed between the two calculated positions so that it would be able to pick up both birds at the same time. The thing is it would be "off center" to either bird by about 2 degrees. The question is would this adversly effect the signal strenth enough that I would have no reception? Or would the size of the dish compensate for the loss created by the 2 degree miss alignment? Any ideas on this theory?

I"m pretty sure theory 1 using two LNBFs with the stronger directv LNBF offset will work. Do you think theory 2 using the combo LNBF centered between the 2 focal points would work?

Let me know! And thanks to all once again!

Eric

theory 2 will not work. KU Band satellites are much weaker than DBS sats and you really need to be nuts on to get good signal quality. DBS has room for error. KU had very little room for error.

 

[jags1]

theory 2 will not work. KU Band satellites are much weaker than DBS sats and you really need to be nuts on to get good signal quality. DBS has room for error. KU had very little room for error.

That's what I thought also. The FTA KU LNBF has to be right on the money. So what if I center the dish and FTA LNBF on the 97W bird. FTA would be great but I would now be 4 degrees of the 101W Dirctv bird. Is the Directv DBS signal strong enough to overcome a 4 degree error in pointing?

Let me know!

Thanks!

Eric

 

[Mr Tony]

. FTA would be great but I would now be 4 degrees of the 101W Dirctv bird. Is the Directv DBS signal strong enough to overcome a 4 degree error in pointing?

Let me know!

Thanks!

Eric

yep it will be fine. Here is a photo of my setup (at one time....it changes constantly) of G18 (123W) and a DBS attached for 119W (for NASA TV)

Here is a more current dish of 107.3 (for Shaw Direct...a Canadian TV provider) and 119 (the one on the right)

I guess the one question I have is what is the "normal" dish size for Directv in Hawaii? If I remember right, Dish requires a 24" minimum dish and you cant use the stock dish that we do "on the mainland"

 

[Anole]

Are you still hell-bent on the six foot prime focus dish?
If so, let me repeat something very important to your project:

And as a last thought, if you use a prime focus dish, make sure your LNBs match the F/D, for maximum performance.
Otherwise, the typical Ku LNBs designed for 3' offset dishes, will only see the middle of your dish, and not all the way to the edge, wasting your money.

If you ignore this admonition, your performance will be compromised!

I'm not gonna say "I told ya so", later on. I'm sayin' it now!

 

[jags1]

Anole,

Yes I understand how the F/D works. That is why I'm looking at the Invacom QPF-031 with the AF-120 feedhorn. This setup is optimal for a large prime focus dish. However, it now looks like my idea of using this combo LNBF may not work for me unless I motorize the dish. My next choice will be the BSC321SP which is a Linear Ku LNBF designed for the big prime focus dishes. It will match up with the F/D ratio of 0.38 of the 6 foot dish. It will give me full illumination of the dish and maximum signal strength for the weaker FTA signal from G19 at 97W. I also realize that this will leave me with having to use a standard 3 foot offset LNBF for my Directv DBS signal from 101W. Not optimal but since I will be off setting that LNBF anyways it wouldn't be able to fully illuminate the dish anyways. Plus it may not give 6 feet of dish but it will definately give me more than 3 or 4 feet. And that Directv signal is stronger also so using it should not be an issue.

My main thing is to get a super strong FTA KU signal from G19 at 97W and especially from that weak transponder that carries the DMC channel. Plus I have 5 acres and a small dish would look silly on this big piece of land!!


Iceberg,

Thanks for the photos! I'm pretty sure using 2 LNBFs will work. Was just thinking I could get by with just using the one combo LNBF but the 4 degree misalignment I would have on the Directv 101W would probably be too much and I wouldn't get a good enough signal. And yes, Directv in Hawaii requires a 24" minimum dish and you cant use the stock 18" dish that is used "on the mainland".

Any other input will be greatly appreciated especially regarding the use of the single combo Invacom QPF-031 with the AF-120 feedhorn.

Thanks everyone!!

Eric

 

[Mr Tony]

My main thing is to get a super strong FTA KU signal from G19 at 97W and especially from that weak transponder that carries the DMC channel. Plus I have 5 acres and a small dish would look silly on this big piece of land!!

Thats the spirit Yeah the last thing you want is to have the dish keep going out when it rains.

And yes, Directv in Hawaii requires a 24" minimum dish and you cant use the stock 18" dish that is used "on the mainland".

Thats good to know. I didnt know if it was a 24 or a 30" minimum for DirecTV

 

[jags1]

Thats good to know. I didnt know if it was a 24 or a 30" minimum for DirecTV

I've seen both 24" and 30" . I'm sure the 24" is marginal at best. 30" would probably be a lot beter for Directv here in Hawaii.

Thanks again!

Eric