C band LNB on Fibo 120?

[aceb]

By the looks of things you can't get much further west than 37.5W? A shame if you can't because there's lots more available to 1.2m dishes on 55.5 and 58W. As it happens I've got my 1.2 Gib set up on a temp mount to align the new motor tomorrow, if all goes to plan I intend to try the C band LNB on it after seeing as I've now got the Gibertini C band LNB bracket. Will keep you posted!

 

[Trust]

@ Captain Jack , why dont you move the house backwarts ?

dont forget to try http://www.satellites.co.uk/forums/topic/157270-c-band-lnb-on-fibo-120/?p=832382
without the feedhorn the lnb must be closer to the sub as the clamp can hold it . see picture



another suggestion http://www.satellites.co.uk/forums/topic/115537-dielectric-plate/?p=834316

 

[Captain Jack]

By the looks of things you can't get much further west than 37.5W? A shame if you can't because there's lots more available to 1.2m dishes on 55.5 and 58W. As it happens I've got my 1.2 Gib set up on a temp mount to align the new motor tomorrow, if all goes to plan I intend to try the C band LNB on it after seeing as I've now got the Gibertini C band LNB bracket. Will keep you posted!

Yeah, 37.5W is my limit. Beyond that, there's a house.

@ Captain Jack , why dont you move the house backwarts ?

dont forget to try http://www.satellites.co.uk/forums/topic/157270-c-band-lnb-on-fibo-120/?p=832382
without the feedhorn the lnb must be closer to the sub as the clamp can hold it . see picture

Trust combi.jpg


another suggestion http://www.satellites.co.uk/forums/topic/115537-dielectric-plate/?p=834316

Yeah, will be playing with various depolarisers and moving the LNB about. Need to create some sort of mechanism for ease of adjust-ability.

Those Panorama LNBs look quite expensive... do they perform better?

 

[Trust]

Its a standard Golden Interstar with a single BlackUltra Ku lnb attached by me , another test by me (not so succesfull )

 

[nelson_b]

a good set of results -- Captain Jack --
i,m sure more will come - as you experiment with positioning and finding a
polarising plate that suits the fibo setup .

regards ---

 

[Captain Jack]

I will try removing the feedhorn tomorrow and move the LNB close and see if that increases any signals. Will try Trust's method...seems simple enough. I could use some nails for that I guess and something I will probably have lying around.

Will then try VS's T-plate out of some chopping board.. or maybe eBay 380547428295 ? Seems expensive though. What's the optimal thickness for that?

DOS plate looks more complicated, so will probably try it last. But I really need a better location for my dish!

 

[Kveys]

Good to hear Captain Jack you got something from C-band. More will come I think
Btw. try 18W 4018R 4444 ZBC (Zimbabwe) moved from 60E. Its english language programmes but also BISS. Behind the trees here but earlier 60E was watchable.

 

[nelson_b]

Will then try VS's T-plate out of some chopping board.. or maybe eBay 380547428295 ? Seems expensive though. What's the optimal thickness for that?

DOS plate looks more complicated, so will probably try it last. But I really need a better location for my dish!

The - V.S. style T-plate gives the best results across all frquencies on my channel master dishes -- the DOS plates are also very good - but theT plate has the edge for me on my setup -- both are way better than the standard type plate that comes with the l.n.b.

got my chopping boards from a local "household supply" type shop for about £3.50
its 8mm thick (tried 4mm but nowhere near as good)
the whole thing is 176mm long

it sits 57 mm inside the thoat
and projects 70 mm beyond the feed. (these lengths may not be best for your fibo but may be a good starting point --

cheers --

 

[Captain Jack]

Thanks for that. Need to play around with that, especially if I get better results without the feed horn. Also hope the t plate doesn't stick out too much so that it hits the sub reflector.

 

[Kveys]

nelson_b I linked your picture for finnish sat-forum, hope you dont get mad? Theres maybe one "new" C-band M8. Its quite boring to talk by itself there

 

[aceb]

I may just wait for the ice to melt off the dish before I start lining up the motor.

 

[pride21]

hi CJ found a plate i had been experimenting with if you pm your address to me i will send it to you.

 

[Captain Jack]

Thanks for the offer pride! PM sent

Just bought a chopping board - time to chop it up!

 

[Captain Jack]

Hello boys and girls,

Another sunny but chilly day here, so kept playing with the dish. Bought the chopping board - looked like 8mm - for £6 from a "Pro Cook" shop... how little did they know what I was going to do with it!

Anyway, got home, and cut out three shapes. First I did was the T plate but the more I thought about it, the more I thought that it wouldn't work well if I was to get rid of the feedhorn as per Trust's suggestion. The T plate works for feedhorn set-ups because depolarisation starts at feedhorn level. As I wouldn't have one, it wouldn't really work properly. Based on these thoughts, I also did a T plate without the T bit (long piece) which would protrude to around the same level beyond the LNB neck. The third piece was just a slightly longer version of the factory supplied plate.

Before I tried the plates, I created a spacer/bracket thing to allow me to move the LNB closer to the sub-reflector. I found that without the feedhorn I could obtain more or less similar results - had 11.4dB on 3E on one of the linear transponders, which is an improvement over 10.5dB I had before. The benchmark TP (Star Times on 5W) was slightly lower at 7dB vs 7.2dB (both with the original plate).

Once I found the optimal LNB position, it was time to try the plates. On a hunch I plonked in the straight strip first and to my surprise, the Star Times transponder jumped from 7db to 7.8dB! This is without any tinkering whatsoever. The T plate gave me around 7.5dB and T part was hitting the sub reflector. I tried trimming it and at various depths but couldn't really beat the straight strip. The smaller one didn't give good results. Eventually with a little trimming and adjustments, I managed to peak it at 8.2dB - but still NO LOCK! What does it want to lock?! Same story with the Viasat TP on 3271L - getting 6dB on there but no lock. Stupid 8PSK...

Next to try is Trust's Coke bottle and DOS-type plate. I think these will bring in better results. Perhaps those with feedhorns should try combining the T plate with DOS plate so that depolarisation starts at feedhorn level?

Managed to lock some others though that I couldn't before. Got VOA on 27.5W at 3.5dB (more than enough to lock with 1/2 FEC) ,TV Congo TP 3633R and GlobeCast TP 3727R on 5W. Russian transponders on 11W went up from 2dB to 5.5db! Amazing.. Going to see what else I can catch now...

 

[Trust]

Nice job !!
if its difficult to find the right bottle size , think about candle-cups from the cemetery , I found several sizes there .

 

[Captain Jack]

Hah! Not sure I'll be trowling cemeteries for candle cups!

Got 24.5W! RTB TP... (352x576 - really....?)



No sign of 18W whatsoever...

Fox TP on 1W is showing 3dB but no lock. Other TPs have signs of life but nothing special...

 

[nelson_b]

Perhaps those with feedhorns should try combining the T plate with DOS plate so that depolarisation starts at feedhorn level?

indeed -- this is something i,v not tried --

must give this a go when i get the time to play with satellite things again -- just too busy with work and 2 car m.o.t. preparations - right now.

a few more gains for you today ( nice one )-- i,m sure you are best to disregard the feedhorn on the fibo dish -- being so large it "must " block some of the signal getting to the subreflector -- be interesting to see how "Trusts" bottle depolariser --- and the DOS plate performs on your fibo setup

cheers ---

 

[Captain Jack]

Thanks to aceb for pointing me to a strong 1W data transponder, which I have managed to lock. So another one added to the list.

 

[Captain Jack]

Getting some readings on 30.5E but nothing locked yet...

 

[Captain Jack]

Hey Pride,

I got your plate today and tried it out. It was quite good and gave me results very similar to my chopping board plate - maybe 0.1 or 0.2dB lower. I didn't get to play around much with it as it's bluddy freezing and I couldn't feel my hands after 10 minutes!