Multi LNB Setup Question

[silverfox0786]

HI Guys got a Question for ya


As you know i got Multi LNB setup in my House using Inverto Bullets. They are Known to be a bit pants in high wind and rain and i agree i always loose signal in wind and rain

now my setup is 19.2E, 13E, 23.5E and 28.2E where i have my focus on 19.2E and the other 3 LNBs around it offset from dish

soooo.....


i want to set up a second dish but this time with a triax style setup like our friendly coder Andyblac as shown bellow

13629


Now here is the confusion the dish shown above is not focused on 19.2E is it in between 19.2E nd 23.5E so basically all 4 LNB's are offset from the dish. The consept i understand and am pretty happy with that as this way i can get more LNB space and use the larger TM LNBs as seen in image

now what i ask is my calculations i done what would be my best option. Personally i think option 1 is my best bet

Option 1. I have 13E, 19.2E 23.5E & 28.2E i find the total Arc im gonna use that will be calcualted as such
28.2-13=15.2 This gives me 15.2 Deg of total Arc im gonna use
From there i divide by 2 to get the centre point 15.2/2=7.6
So this means i point my dish 7.6 degs between the 2 which will be 13+7.6=20.6 or 28.2-7.6=20.6
being perfectly in centre i then space out my 2 LNBs 19.2 and 23.5 7.6 degs apart but making sure they are in centre so hence 7.6/2=3.8
So from centre they will be 3.8 degs either side of dish
from there i add my other 2 LNB's 13E on one side and 28.2 on the other side and that way i will have an equal coverage of all LNBS hitting the dish face

Option 2. I have 13E, 19.2E 23.5E & 28.2E i find the only the central Arc between inner 2 LNBs this will be calcualted as such
23.5-19.2=4.3 This gives me 4.3 Deg of Central Arc
From there i divide by 2 to get the centre point 4.3/2=2.15
So this means i point my dish 2.15 degs between the 2 which will be 19.2+2.5=21.35 or 23.5-2.15=21.35
being perfectly in centre i then space out my 2 LNBs 19.2 and 23.5 2.15 degs apart but making sure they are in centre so hence 2.15/2=1.075
So from centre they will be 1.075 degs either side of dish
from there i add my other 2 LNB's 13E on one side and 28.2 on the other side

To me Option 1 sound practical and plausable but really need your opinion on what you guys think is best

[machare]

The further LNBs are from the central axis the less signal they will get, so it makes sense to have 13e and 28,2e the same distance from the centre.
For that reason I would aim the dish at 20.6E

You might be able to put an LNB for 19.2 at 1.4deg of centre and use that to align the dish.

I have a Wavefrontier T90 which is aimed at 12.0E - about half way between 5w and 28.5e. However the dish is calibrated so I know where to put the LNBs. (I also set the skew for 12.0E)

[silverfox0786]

cool thanks machare

i was under the impression that my best bet would be option 1

btw machare if you are using the tips floating round teh net then where did you get the wire frame style lnb holders from

[machare]

My T90 has its own plastic LNB holders which help to set the LNBs at the correct angle. The holders are not as good as they were as they were gnawed, probably by a squirrel.

[andyblac]

just for the record my focus point is on 23.5

[silverfox0786]

that changes thing lol

[Rob van der Does]

I have your option 1 (for exactly the same satellites) on two dishes for the very same reason as you gave: all LNB's are centred as much as possible.
The Inverto's are indeed a bit wide, so they are very close together and some are slightly misaligned, but nevertheless I never lost signal (not even on 28.2 with is not supposed to hit the mainland at all).
Don't forget to give the whole dish a skew (the average of the skew needed for the individual LNB's).

[silverfox0786]

cheers rob

least i wasnt going mad with my theory and it it a practical solution

now to get on to WOS and get the kit hehe

[banie01]

Well I have my MultiLNB set up as follows,
I aimed and peaked the dish at 16e(was the weakest sat when I set up).
I then modded a Triax MultiBlock to allow me a centrally mounted LNB, I use Inverto Singles at 13e and 16e along with an ALPs at 19.2 and I moved an Inverto Multiconnect to 23.5e to keep correct spacing.
With a centrally mounted LNB the Triax multiblock is a great piece of kit.
I have 28.2 at @12 degree offset and it performs better at this offset than it did on a zone 2 minidish(BBCHD at 95%SNR/AGC C4HD @99%SNR+93%AGC BIO HD 75%SNR/93AGC)
All told I now have 7 LNBs on my multiblock covering 4.8e,9/10e,13e,16e,19.2e,23.5e and 28.2e on a TD88 and the 3 degree spacing isn't an issue at all once you plan a little ;)

[Rob van der Does]

.....least i wasnt going mad ....
Hmmm :confused: I never said that :sofahide:

[silverfox0786]

Hmmm :confused: I never said that :sofahide:

yes i know you didnt hehe ;)