Starting Over: Dish alignment

[EMPB]

I'll be re aligning my Dish next month as I am sick of getting nothing from 4W, when I know I used to get and should get some of the Europe Beams (also lost ENTV on 5W).

My East Arc is set up stronger at Present (Badr4 26E superb even in bad weather). But I think the Dish was Aligned in a hurry on 13E and adjusted on 26E last time, need to do it right on 0.8W/1W this time (my reception Satellite Arc is generally 45E to 45W, although 47.5E would be a nice addition).

We will be getting scaffolding this time as the dish is bulky and difficult for Colin to align while standing on a ladder

I've just e-mailed him the link to see what he thinks of this..... !!!!

 

[EMPB]

So as well as 3E from footprints I should also be looking to get something from:

Eutelsat 5 West A @ 5°W (C-Band Coverage):

NSS 7 @ 20°W (East Hemi C-Band Coverage):

NSS 10 @ 37.4°W (C-Band Coverage):

NSS 806 @ 40.5°W (East Hemi C-Band Coverage):

Looking forward to testing C-Band, if Colin is up for this project - are there any non DIY brackets with less than 6 degree between LNBs available that will work for 1 Ku-Band & 1 C-Band LNB, and what about weight issues on the LNB arm that I have read about issues with elsewhere?

 

[mdt]

you might be better off trying to fashion a bracket yourself from and exhaust clamp and a flat piece if steel bar with a few holes drilled in it or just using cable ties ect. as for weight the c-band lnb,s that everyone uses are lightweight and are the same as a standard lnbf. by the way who is colin? regards mdt

 

[EMPB]

Colin is a fully qualified Electrical Engineer who does most of the hard work whilst setting up / installing Dish setups (eg I only did the cable runs throu my loft, last time my dish was set up, Colin did all the alignment etc)

I also read about LNBs which provide both C-Band and Ku-Band from the same LNB unit particularly the WS-ESX741U:



(but I believe there is a Russian manufactured one with very good specs, can anyone tell me the model/part number?), the C-Band part of the specification does not seem any different to any other C-Band LNB but the Ku-Band part of it maybe not up to fringe reception, would this fit on a normal bracket thou I wonder and therefore be the best option for the C-Band part of the set up?

And how much signal is likely to be lost by not using the Dielectric Plate as obviously Linear H/V is required from the Ku-Band, But Circular R/L is required from the C-Band.

 

[cappuccino99]

42dBW on 3e is receivable on a 1.1m or 1.05m in offset, but 39dBW even on the focus on the old numbers jumps to estimates of 1.7m, they are the old estimates & newer LNBs & tuners/ receivers should help plus add a bit for accepting limited margin.

I say you're better concentrating on getting the KU absolutely spot on 1st & when you want to go hunting for C Band, swap lnbs & see how the C Band does in the focus first, you can tighten up the KU's LNB holder so it keeps it's position & I'd make a C band holder to swap to, just make sure it's aim angle & center line through it's waveguide is the same as the KU's, the waveguide rim should end up a little closer to the dish face than the KU's feedhorn cap, don't expect big numbers but it is more robust than KU.

 

[mdt]

@empb, as regards the C and Ku lnb,s in your picture from what ive read they are pretty awfull in the Ku although someone who has tried one could give you their findings,regards mdt

 

[nelsonb]

@empb, as regards the C and Ku lnb,s in your picture from what ive read they are pretty awfull in the Ku although someone who has tried one could give you their findings,regards mdt

hi --
yes i bought one like the one in the photo above - to fit to a 1.8 channel master , thinking that the size of the dish might overcome the k/u weakness , but it didn,t - it struggled to pull in all the transponders on the strong sats .

in fairness-- they are designed for very large prime focus dishes - and the feed of the k/u part of the l.n.b. had flat scalar rings
so not suitable for offset dishes -- also some of the signal is blocked by the C band receiving section - and if the dielectric plate is in the l.n.b. -- signal to the k/u part is reduced further still .

i think cappuccino99,s suggestion of getting the k/u spot on - then trying a regular C band l.n.b. and then fine tune that- in the centre focus ------ sounds the best bet --
then maybe fit it as an offset if it performs o.k.

but as has been stated earlier the amount of C band channels receivable will be pretty limited - only some of the very strongest.

regards - nelsonb

 

[EMPB]

The same model number WS-ESX741U / WS International 741U Universal Ku Quad Polarity Single C & Ku Band LNBF? Or just "looks" the same....?

I think all the problem is combined ones look the same as any other C-Band LNBs anyway.... So would be nice to know, reports of this one "BSC621-2D C/Ku LNB"

Should your area require the Ku and C polarities be opposite you can follow these simple instructions to change your BSC621-2D C/Ku LNBF.

Separate the C and Ku housings by removing the three screws that hold them together.

Remove the LNBF from the Ku housing by removing the 'F' connector nut and pushing on the 'F' connector until the LNBF is pushed out of the housing. Use care not to damage the 'F' connector.

In the picture below, using the left slot will make your Ku polarity the same as your C polarities. Using the right hand slot will make your polarities opposing or reversed.

say good for projects and as being good on 90cm dishes, but it looks the same...

 

[nelsonb]

hi - EMPB -
the model i bought was a DMX741U -- and although it did work , it just wasn,t up to my expectations -- and in the end i fitted seperate l.n.b,s -- k/u in centre and C band -offset --.(the loss from the C band being offset was marginal to be honest)
i,m not trying to put you off experimenting with a combination unit though -- a top notch combination l.n.b would be brilliant - just a bit sceptical after my findings with the DMX741U

regards nelsonb

 

[EMPB]

hi - EMPB -
the model i bought was a DMX741U -- and although it did work , it just wasn,t up to my expectations -- and in the end i fitted seperate l.n.b,s -- k/u in centre and C band -offset --.(the loss from the C band being offset was marginal to be honest)
i,m not trying to put you off experimenting with a combination unit though -- a top notch combination l.n.b would be brilliant - just a bit sceptical after my findings with the DMX741U

regards nelsonb

Reading US forums the 741U is preferred over the BSC621-2D but that's for their Circular Polarization Ku and C-Band transmissions. So I might try the BSC621-2D in Prime focus for both and then just as C-Band in offset if its Ku-Band is terrible.......

 

[cappuccino99]

say good for projects and as being good on 90cm dishes, but it looks the same...

The trouble is it's the manufacturers saying that and they are referring to areas that are generally well inside C Band footprint's best areas.

I don't want to put anyone off either though, it would still be great to have a really top performing C/Ku band LNB on a 1m/1.1, circular and linear and it only takes someone coming up with a better way of doing it. I've used the combi C/KU up to 2.4m and they work but as has been said the Ku reception suffers but it can still be handy, have used it as a solution of sorts for circular C & Ku.

Btw, There's an odd design in some newer c band lnbs with tapered bodies sold with the c band lnb holders that hasn't been thought through, in other words they only tighten up in one area but as you alter the focus closer they becomes loose, if you end up with one you can use 3 blunted self tapper screws positioned like the bolts on the feedhorns.

 

[EMPB]

I do agree with you to some extent as the 90cm Offset Dish is sold for American reception of US Birds, but it is a project dish refered to on many forums as the "HotDish 90" project, so not just marketing ploy, can only buy C/Ku-Band LNB & give it a try.

 

[EMPB]

Also cover the C Band lnb's cap with plastic to make it waterproof as C Band lnbs are designed for prime focus dishes which means they always face down so only usually have drain holes but on offset dishes they point upward.

Any plastic.... ie Carrier Bag, Cut away from plastic cup... etc etc ?

 

[cappuccino99]

Any plastic.... ie Carrier Bag, Cut away from plastic cup... etc etc ?

Try them held over the front of the lnb when on a C band signal like 3e & monitor the signal.

 

[cappuccino99]

Try them held over the front of the lnb when on a C band signal like 3e & monitor the signal.

Checked it with a very thick industrial polythene bag & doubled it, couldn't measure any difference on a C band tp on 3.3e -

Al Hidaya 3765H 20328 vpid 0123 apid 0690 ppid 0123,

meter readings before and after

MER 7.9 dB

Noise Margin - 2 dB

EVM - 44.7%

and 65% Q on a TM5402HD

on a 1m in NW with 13k c band lnb with no feedhorn.

 

[cappuccino99]

MER 7.9 dB

Noise Margin - 2 dB

EVM - 44.7%

and 65% Q on a TM5402HD

on a 1m in NW with 13k c band lnb with no feedhorn.

Just hung a multi scala ringed prime focus feedhorn on the lnb & just at a rough angle as the lnb arm was in the way & those figures jumped to near 80% Q on the Technomate's meter and on the meter 10.7dB MER/ Noise margin went up to 5dB & EVM was down to 31.6% and it started raining.

you can just as easily seal the holes in the feed cap that comes with the C band LNBs with mastic, maybe a smear of vaseline round the rim.

 

[EMPB]

UPDATE

In Offset of 4 degrees at the moment. Got 4 transponders so far, the Lybia Muxx at 3.3E, Eutelsat TEST at 3.3E, RADIO AFRIQUE 5W, RSCC Muxx at 11W (the strongest signal and includes Rossia 2 [Sport]).

My Triax is a 1.06m one. Anyone know how much % area of dish is lost for each degree a 2nd LNB is Offset, there must be a matamatical calculation for this somewhere. But been unable to find it using "Search" on forums and general Google searches.

Not yet fitted the Scalar ring.... so lots still to do over the next 2-4 weeks.

 

[cappuccino99]

The new RSCC TP 4013R 10050 on 11w just opened up a few days ago and could be the strongest C Band (circular or linear) EIRP in England, it does have a very very high break up level though with DVB-S2/8PSK -the fec is 3/4 btw, Flysat has it as fec of 7/8 although it may have altered after their report.

 

[EMPB]

Yes I scanned it in as 4013R (H) SR 10050 FEC 3/4 DVB-S2 (8PSK) on Humax HDCI-2000

Strength 65% Quality 70%, no break ups

+ Even thou weather conditions are not supposed to effect C-Band as much as Ku-Band, I expect the unusually hot weather helps a bit

+ I can prob nudge Strength & Quality up a fraction by nudging the dish position East or West a Fraction but just tuned into byu tv global on 15W on my Ku-Band Set up, and the aprox 4 degree offset locks 11W in C-Band straight away...

So with a 4 degree offset am I still looking at 1M+ dish or more like 90cm, anybody know...

My Triax is a 1.06m one. Anyone know how much % area of dish is lost for each degree a 2nd LNB is Offset, there must be a matamatical calculation for this somewhere. But been unable to find it using "Search" on forums and general Google searches.

......trying to use Purplesat's figures as a guide to what to try and tune in next.

 

[pevla]

I know that this is a silly question, but what is the difference between C and Ku Bands?