Badr 4,6. 26 E

[dovercat]

Sounds like my Moteck sg2100a is an atypical lemon then, just my bad luck. It had play from new, and has developed a problem young about 3years old.
Does anyone else have problems with it not reliably and accurately to 0.15 degrees going to its stored positions? Maybe that is a problem with my receiver?

I do think the Moteck looks and weighs like a toy in comparison to old 36v motorized mounts, considering how heavy duty they are in comparison. Maybe they were overkill or designed to withstand a once in a lifetime storm. The wind loading on a 1.2mtr solid dish in say gale force winds is massive. I have had a 1mtr solid dish in an exposed location when gales were toppling trees, chimney stacks etc.. That buckled my old polar mount, with this mount I would worry it might snap.

Still it was alot cheaper and the motor is quieter than the old 36v Jaegar smr-g99 h-h it replaced.

So the Triax is marginally smaller and a bit heavier than the Televes.
I went with the Televes over the Triax because I could get it significantly cheaper and figured the most important factors with a dish are size and build material. Triax quote gain at 11.7GHz while Televes use 11GHz, since I believe gain increases with frequency this makes the specs not directly compariable, does anyone know how to convert gain from 11GHz to 11.7GHz.

You also seem to use Lnbs that are not dish specific, I found the Televes 0.5dB better suited to the Televes dish than other 0.1-0.2dB Lnbs I had lying around. I thought having a good Lnb-Dish match and tweaking the Lnb position for best signal quality would yield about as good as I would get. How much improvement do you get with these Lnbs since the specs are not very reliable/revealing. I was under the impression that a Lnb upgrade was generally not worthwhile as it is generally only equivelent to increasing dish size by a few cm. So only worthwhile if their are channels right on the borderline of having a reliable-stable picture.

 

[dovercat]

Hmm the 1mtr andrews is 106x116cm, the 1mtr prodelin 105x115cm, the 1.1mtr triax 102x110cm. My televes is 102x113cm so it might be the 1mtr Televes afterall. Anyone know what dimension the Televes 1mtr and 1.1mtr dishes are?

 

[dovercat]

Thinking about it my Televes dish 102x113cm must be the 1mtr Televes. Since dish size dictates beamwidth and that is determined by the width of the dish on a offset dish. So when the Triax TD110 102x110cm is sold as a 1.1mtr dish it is being mis-sold because the beamwidth is not correct for a 1.1mtr dish. Beamwidth being the most important aspect of a dish along with Gain, as beamwidth determines how much noise it can elimante.

 

[Robbo]

Yes the Triax is mis-described by the manufacturer as a 110cm dish, nothing new there then, it makes it seem bigger than it is to sell it.

 

[Lazarus]

You also seem to use Lnbs that are not dish specific, I found the Televes 0.5dB better suited to the Televes dish than other 0.1-0.2dB Lnbs I had lying around. I thought having a good Lnb-Dish match and tweaking the Lnb position for best signal quality would yield about as good as I would get. How much improvement do you get with these Lnbs since the specs are not very reliable/revealing. I was under the impression that a Lnb upgrade was generally not worthwhile as it is generally only equivelent to increasing dish size by a few cm. So only worthwhile if their are channels right on the borderline of having a reliable-stable picture.

The only truly effective way to match an LNB to a Dish is empirically: It is rare to be able to get hold of full specs for LNBs that give plots of their various characteristics vs. frequency.

Figures for eg Noise, Gain, Cross-polarisation rejection are normally "headline" figures applying only to a small part of the band.

Many of us have a small selection of LNBs of different manufacture and spec. and just fit what appears to work best for our particular needs.

 

[Huevos]

does anyone know how to convert gain from 11GHz to 11.7GHz.

It's a linear relationship between frequency and dish size. For example, if a 1 metre dish @ 11700 MHz = 39.7 dB if we dropped to 11000 MHz to remain at the same gain you would need to increase the dish face to ((1m*1m)*(11700/11000))^0.5 = 1.03 metres (horizontally). This is a change in dish capture area of 6.3%, which equates to about 0.16 dB.

 

[dovercat]

Thanks so if manufactures specs are to believed. Triax TD110 (102x110cm) gain 40.2dB at 11.7GHz is equivelent to about 40.04dB at 11GHz, while the Televes 1mtr (102x113cm) at 11GHz claims a gain of 40.5dB.
So in theory the Televes is marginally better than the Triax has anyone had both dishes to compare in the real world.

 

[Huevos]

I found the Televes 0.5dB better suited to the Televes dish than other 0.1-0.2dB Lnbs I had lying around. I thought having a good Lnb-Dish match and tweaking the Lnb position for best signal quality would yield about as good as I would get. How much improvement do you get with these Lnbs since the specs are not very reliable/revealing. I was under the impression that a Lnb upgrade was generally not worthwhile as it is generally only equivelent to increasing dish size by a few cm. So only worthwhile if their are channels right on the borderline of having a reliable-stable picture.

Matching the feedhorn to the dish is important of course but having a good LNB attached to that feed is very important too. For example a Black Ultra, in my experience, on an offset dish out performs any other LNB I've tested when it comes to digging weak signals out of the noise. Most can't come within 0.5dB signal to noise which is a huge amount.

Thanks so if manufactures specs are to believed. Triax TD110 (102x110cm) gain 40.2dB at 11.7GHz is equivelent to about 40.04dB at 11GHz, while the Televes 1mtr (102x113cm) at 11GHz claims a gain of 40.5dB.

Well herein lies the problem; those figures are the external dimensions of the dish, not the capture area.

Personally I doubt if someone set up and aligned a sample of each of those dishes and then handed the two cables to someone who didn't know which was which (blind test) that that person would notice any difference even with very good test equipment.

 

[dovercat]

Then again the Televes only has about a 2-3% larger surface area than the Triax and you would only realize that with a well matched Lnb. Since they both have the same F/D relationship - shape, unless they have markedly different efficiency scores, which I doubt, that is much too little difference in surface area to give a 0.46dB difference in gain. I assume it should give something more in the region of a 0.08dB difference.
So the manufactures specs are probably still not comparable, do they use a industry standardized measuring protocol.

 

[dovercat]

Since UK dealers stock Inverto lnbs, but not yet the Black Ultra, I will pick one up in January if UK dealers start to stock them. I expect there is quite a bit of variability between individual Lnbs and the Lnb to Dish matching has a significant effect. So what is a great Lnb for one person might not be so great for someone else. But it is cheap so I will give it a go.

 

[dovercat]

The satellite transponder list _http://www.lyngsat.com/badr.html
has links to the footprint maps, it is somewhat misleading as I get MBC channels easily with a 1mtr dish in Oxfordshire and it claims that is completely out of the footprint.

With Badr 26E dish size - dish beamwidth and accurate dish alignment are crucial as you need to isolate Badr 26E from Astra 28.2E.

Using _http://www.dishpointer.com/ My location gives 28.2E as Azimuth 144.3 and 26E as 146.7, so only 2.4 degrees difference.
I get it fine on a 1mtr dish. Half beamwidth to -15dB with a 1mtr dish is 2.4 degrees at 9.7GHz, 1.949 degrees at 11.7GHz, 1.82 degrees at 12.75GHz. Signals from Badr start at around 11.7GHz so I do not get interference from Astra effecting reception of Badr.

An 80cm dish has a half beamwidth to -15dB at 9.7GHz of 2.99 degrees, at 11.7GHz of 2.48 degrees, at 12.75GHz of 2.28 degrees. A 60cm dish has a half beamwidth to -15dB at 9.7GHz of 3.99 degrees, at 11.7GHz of 3.31 degrees, at 12.75GHz of 3.04 degrees. Satellites with footprints aimed at the same location usually have 3 degree spacing.

_http://www.satsig.net/pointing/antenna-beamwidth-calculator.htm

Bear in mind that not all dish manufactures 1mtr dishes are the same they vary from less than 95cm to over 105cm wide, as some round up and others use the height instead of correctly using the width for their dish sizes. I have seen posts on forums giving the following actual sizes
Gibertini 1mtr is apparantly only 95x102cm
Orbital 1mtr is apparantly only 95x110cm or 98x107
Triax 1.1mtr is apparantly only 102x110cm
Televes 1mtr I have is 102x113cm
Prodeline 1mtr is apparantly 105x115cm
Andrews 1mtr is apparantly 106x116cm
The actuall illumination of the dish will be less than the dish size, as you do not want edge noise, and generic universal Lnbs are designed for a standard F/D ratio, so they maybe not be looking at the whole dish, which is why I currently use a lnb by my dish manufacturer.

Going back somewhat off topic to Lnbs the main thing that makes me very skeptical is their unbelievable noise figures. My understanding is that the minimum noise level possible of an Lnb is dictated by the pin diode used in the detector circuit. These diodes used to be rated as adding about 40 degrees K, which translates as >0.5dB. So how can manufactures honestly claim noise figures lower than 0.6dB 43K or 0.5dB 35K. I have read that they might be able to get as low as 0.3dB in a small part of the frequency range rather than a average across the frequency range. But most seem to claim noise figure of 0.2dB 14K and 0.1dB 7K which are I think unbelievable. The old low noise Lnbs claiming 0.7dB were probably alot more honest.

While I am rambling on about Lnbs, might as well mention that phase noise is one of the most important specs for digital reception as it corrupts the digital data stream, this is a different spec to the headline Lnb noise figure a larger negative number is better.
Local oscillator stability is also crucial to the receiver getting maximum signal quality from the lnb, and especially important with narrow - low symbol rate signals.
Discrimination between Polarities is also important particularly if the satellite signal has one polarity at the same or close frequency giving alot stonger signal than the signal on the other polarity.
Finally Lnb gain usually between 40-65dB increased gain is always at the expense of increased noise but may improve reception if your receiver is a bit deaf or the cable run is very long, but you can have too much shouting too loud at the receiver as well as too little.

When putting the dish together, and checking the setup, you want to check the lnb is looking correctly at the dish to get best results. A old tip for doing this is putting a torch where the lnb will go and seeing if it is being aimed at the center of the dish, alternatively using a piece of dowling to check the lnb is aimed at the center of the dish.

Once the lnb is in place and you are receiving pictures, adjusting how far the lnb sticks through its holder towards the dish for best signal quality, the nearer its feedhorn to the dish the less area it is collecting from lower signal strength, like a torch in reverse, but also the less edge noise, and if the lnb is actually looking past the edges of the dish you are going to be getting alot of noise.

Then you have rotating the lnb for best signal quality on horizontal and vertical polarization, as this determines how much signal cross contamination there is between the polarized signals, lots of cross contamination equals higher signal strength but lower quality. On a motorized dish you want to adjust lnb skew with the dish pointed at the satellite highest in the arc, closest to the motor pointing true south, motor position O. As when the dish rotates on the mount it skews the dish. With a motorized system lnb skew is a compromise, old analogue systems had a seperate system for adjusting the skew per satellite but satellites are alot stronger now and lnbs better.

 

[Huevos]

The satellite footprint map at _http://www.lyngsat-maps.com/maps/badr4_fss.html, it somewhat vague as it claims you need 85cm to 135cm dish at my location in Southern England. I get it fine on a 1mtr.

What transponders? I'd bet there is no sign of the MBC channels or Fox Movies. They must be at least 10dB down on Astra 2A North and the transponders share almost identical frequencies and polarities.

On the LNB noise figure, there is no standard for measuring this. dB is a relative unit so is meaningless unless we know what the measurement is relative to. If it were relative to a theoretically perfect LNB then 0.1 would be a feasible figure.

On beamwidth, don't forget 2º really means 1º, i.e. 1º each side of the centreline.

 

[Lazarus]

What transponders? I'd bet there is no sign of the MBC channels or Fox Movies. They must be at least 10dB down on Astra 2A North and the transponders share almost identical frequencies and polarities.

MBC is (are?) an odd one: Despite being well out of the published MBC Special footprint, many of us do get MBC fairly well. 1.1m in my case, reports of 1m in the Midlands and even 1m in Scotland, so like many things in the Satellite hobby, what you get in practice may exceed the theory (or vice versa!)

Not a sniff of Fox Movies or anything else from BADR 6, of course!

 

[Huevos]

what you get in practice may exceed the theory

True! I set up a 50cm dish on a balcony the other day for MBC and Fox off of 26ºE. In theory it shouldn't work but I got about 9dB signal to noise which even gives a bit of rain margin with the 3/4 FEC.

 

[Vipersan]

I am in total agreement Gordon ..
If anyone cares to check back to post 30 of this thread ..
I added a snapshot showing MBC mux with 11 scanned channels ..
..first item on the list in fact..
I wont deny I was surprised to get much of anything from this sat ... but would indicate that the footprint maps are not very accurate in this case..
rgds
VS

 

[dovercat]

What transponders? I'd bet there is no sign of the MBC channels or Fox Movies. They must be at least 10dB down on Astra 2A North and the transponders share almost identical frequencies and polarities.

On the LNB noise figure, there is no standard for measuring this. dB is a relative unit so is meaningless unless we know what the measurement is relative to. If it were relative to a theoretically perfect LNB then 0.1 would be a feasible figure.

On beamwidth, don't forget 2º really means 1º, i.e. 1º each side of the centreline.

Quite right that footprint map was not for MBC, I have edited my previous post. Despite in theory not being within the footprint I easily get the MBC channels with a 1mtr dish in Oxfordshire. At 26E I generally watch only the MBC channels and Dubai One as they show lots of English language programs with Arabic subtiles.

I think there used to be a standard for measuring Lnb Noise figures, at least I think manufactures all did it the same. If the manufactures have started making their own different measuring criteria then the specs are only relevent when comparing lnbs by the same manufacturer, unless they makeup the measuring criteria on a per lnb bases. I can not stand misleading sales tactics, dish mounts rated for dish sizes only in fair weather, 1.1mtr dishes that are actually 1mtr dishes, 0.1dB Lnbs that are actually 0.6-0.7dB, what has happened to the world, manufacturers used to want to have a trustworthy reliable image.

Beamwidth quite right again, I have misunderstood and have edited my original post.

 

[dovercat]

View attachment 25702

A photo of my current Moteck sg2100a with my old Jaeger SMR-99G H-H below for comparison, The Moteck weighs at least 1kg less. Rember the Jaeger is rated only up to 1.1mtr while Moteck claim suitability for 1.2mtr dishes and my dish is only 1mtr (about 69% of the surface area of a 1.2mtr). 36V motorised mounts designed to take 1.2mtr dishes are in the region of 4x or more heavier than than the Moteck sg2100a.

I have also discovered that a DiSEqC motor increases the noise in the signal - receiver signal quality ratting, in my case having about twice the effect as the difference between the best and worst LNBs I own.

I have read up on satellite dish specs. The Triax dish spec using 11.7GHz instead of 11GHz like Televes does not guarantee that it will be quoting a higher gain figure than if it used 11GHz, as the higher the frequency the more small deviations in the dish will reduce gain. So using a higher frequency to measure dish gain is a sign of quality not a way of boosting the gain figure.
Converting the spec gain figures to a avearage 65% efficiency offset dish you get. Televes (102x113cm) 1mtr is equivelent to a 1.14mtr dish with 65% efficiency. Triax TD110 (102x110cm) is equivelent to a 1.04mtr dish with 65% efficiency. The televes is slightly physically larger and measures gain at a lower frequency so gain is less effected by surface imperfections.

I have also read the specs for the Inverto Black Ultra 0.2dB LNB. I see it is actually NF 0.7dB max (50.72K), which is very marginally worse than my Televes 0.5dB (35.39K). (to compare LNB NF you need to use the max figures, convert them to degrees K then add dish noise temperature of around 30-100K in clear skys more with heavy cloud cover or rain, so the comparison ends up being 80.72-150.72+ vs 65.39-135.39+) Oddly the Inverto appears to be coloured black which is the worst colour for an LNB since you want it to keep cool by reflecting heat not get warm by absorbing it, the Televes LNB is white which is the correct colour for a LNB. So the Inverto might have slightly lower sensitivity to weak signals.
The Inverto also has slightly worse polarity discrimination -23dB Inverto vs -25db Televes so maybe slightly less sensitive on signals with powerful opposite polarity signals.
The Inverto local oscillator stability maybe slightly worse than my Televes, initial +/-1MHz, temperature drift +/-3MHz, working temperature -30 to +60 degrees C Inverto vs +/-2MHz, working temperature -30 to +60 degrees C Televes so maybe slightly more bit-rate errors particularly on narrow - low bitrate signals.
But the most important spec is phase noise and on this crucial spec the Inverto has a much better lower phase noise -90dB Inverto vs -75dB Televes, low phase noise is crucial for good digital reception of weak signals as it is noise being added to the digital signal and on this spec the Inverto clearly beats the Televes.
I will pick one up in the new year and see if it performs better than the Televes due to the lower phase noise. Professional LNBs have local oscillator stability measured in the kHz not the MHz and measure phase noise at 1kHz not 10kHz, so they maybe better.

 

[Huevos]

I have also read the specs for the Inverto Black Ultra 0.2dB LNB. I see it is actually NF 0.7dB max, which is very marginally worse than my Televes 0.5dB. (to compare LNB NF you need to use the max figures, convert them to degrees K then add system noise temperature of around 40-50K) So maybe slightly lower sensitivity to weak signals.
It also has worse polarity discrimination -23dB Inverto vs -25db Televes so maybe slightly less good on signals with powerful opposite polarity signals.
Local oscillator stability is important and on that spec it is probably better than my Televes initial +/-1MHz, temperature drift +/-3MHz Inverto vs +/-2MHz Televes so maybe slightly less bit-rate errors particularly on narrow - low bitrate signals.

Personally I never read the specs. I get the LNB, put it in the breech and connect my meter. Irrespective of the spec sheets of other LNBs I am still looking for any LNB that can come close to the Black Ultra or out perform it for fringe reception.