Setting up prodelin 2.4m dish - advice needed

[zaphex]

Greets to all m8s,

Its been a long time now, having less and less time to spend it on the hobby but in another hand I want to do as stated in subject LOL

Prodelin dish offset 2.4 metre (four parts) fibre glass with anti-ace system on bottom two parts of the dish.

I need to know the following before I proceed to setup backyard for this dish:
1. I need to put at least 5 LNBs on this dish, so I need something to calculate exactly the angle of the bar that should hold LNBs (I need to make this myself). I plan to use 28.2 East to 4 West.

2. Can I use normal LNBs without feed-horns, if NO than what feed-horns should I get? I've read reports that it works with LNBs without feed-horns but I want to be sure before I do anything.

Thanks

Zap.

 

[Robbo]

The angular separation for the LNBs is the same as the angular separation of the satellites in the Sky (but mirrored). That applies to both azimuth and elevation. Either way, you will need to allow for adjustment anyway.


The angle of the bar would also depend on your location. You need to get the LNBs at the correct elevational angular offset from the main LNB, that will determine what angle the mounting bar needs to be. Though since you may or may not be crossing true south, an angled bar may not be sufficient. It would be better to arrange up/down adjustment of all offset LNBs indiviually.

Offset LNBs on a standard dish are not optimal anyway, so you should be able to get away with standard LNBs for the offsets.

 

[zaphex]

Many thanks for the reply Robbo - I am located at Latitude: 42° 39' North and Longitude: 21° 10' East. I am not sure what angle should the bar be and what is the best centre position of the dish would be for me considering I want to get 28.2 E - 4 W (5 or 6 LNBs). Did I get your answer right, standard LNBs without feed-horns will do fine right ?

Of course I will build the bar and LNB adjustment mechanism. Just not sure for the bar, its bending accordingly and its length !?

Thank again m8

Zap.

 

[Robbo]

So you are near Serbia?

Your main challenge will be to get 28E then, I imagine, and if you want Astra 2D even more so. You are going to have to play around a bit to see how well you get that, and if you get it well enough with the 28E LNB at the focus how much you can sacrifice if you move it off focus. Because to get 28E to 5 W may be a struggle otherwise. As ideally with a multi lnb setup, you would focus the dish approximately in the middle of the sats, so in your case at approx 13E. But I fear, that if you did that, the dish would not give enough signal to get you 28E. Might be a reasonable starting point, or maybe 16E, as that should be very strong in your area.

As for figuring out where the LNBs go, you know, you can just stand there with an LNB in your hand, and hold it where you think it might be.

Whether Standard LNBs would work well enough depends on a few factors, one being how strong a particular satellite is, and secondly, how much of an impovement using a matche dfedhorn gives you, over a standard LNB. You can check that on a weaker satellite at focus. You need to do a bit of experimentation.


Oh, and the bar length.. it is based on the azimuth spread of the satellites you want. It can be roughly calculated if you measure the distance from the dish to the focal LNB. Say distance from dish face to LNB is d, then for an angular separation of S degrees, the linear separation will be approx d x Tan(S).
Basic trig.

 

[Channel Hopper]

The focal point of the dish will be provided when you first align the dish to the centre satellite

For optimising of the other LNBs, no technical diagram is going to be as accurate as a reasonably priced meter on the day

If you are using the Prodelin 1244 model the two feed stabilisers will need to be modified so they do not interfere with the signals.

 

[zaphex]

Yes it is exactly prodelin 1244, and sorry but I dont know what do you mean by "two feed stabilisers will need to be modified so they do not interfere with the signals" I never did such modifications and need to know as much as possible before I install it. Not only the dish that costs but also fxing place for it will cost also as I have to alevate the dish approx 3 metres high.

@ Robbo - thank you much m8 but I need moe simplies explanations what is "Say distance from dish face to LNB is d, then for an angular separation of S degrees, the linear separation will be approx d x Tan(S)". and how to calculate it?

As for Satellite signal strength I think 28 E is better here than Thor 1W but considering the size of the dish what so you think is it worth it?


Zap.

 

[Robbo]

Basically, on the larger offset dishes, there are usually two poles on each side to help hold the Lnb arm. Well, they can block the path between Lnb and dish.

Lnb offset- you need a normal scientific calculator to calculate the trigonometric function "tangent".

For example say Lnb to dish face is 1.5m. Says wanted was thor and 13e. Separation is 14 degrees. Take the Tan of the 14 and multiply by 1.5

 

[zaphex]

Ah Tangent, thanks m8, yes its clear now. I think I would have to modify the poles for lnb arm as well, I see your point exactly.
Another question I have m8 (if I formulate it correctly, hope you know what I mean); Should the bar that will hold LNBs be bend in the same angle as the dish itself is (horizontaly).

 

[Channel Hopper]

The LNB holder needs to track the geostationary arc. If you haven't compensated by offsetting the dish surface (the 1244 has no such provision, you would have to offset the pole) then the LNB arm needs to do the job.

Since the 1244 is a 0.8 f/d ratio design, the LNBs required for the best signal would need to be with an appropriate feedhorn aperture, and you are unlikely to find many on the domestic market that work well.

Unless you absolutely have to use the dish in fixed configuration, I would look at building a motor mount for the backplate, and stick a C120 quad LNB on the Prodelin feed that comes with the dish, you would have to drill out additional holes as the usual feed has six in a hexagonal pattern.

 

[Analoguesat]

I dont think you will have any problems getting Astra's 2A 2B & Eurobird 1 on that dish - the European coverages are pretty generous. However 2.4m probably wont be big enough to get Astra 2D channels.

 

[deepbluesky]

Your location is Prishtina. You have chances to get a weak signal of some Astra 2D frequencies but only if you will use a suitable feedhorn (exact f/D) and align it to 28.2E. Take care as well for the LNB skew. The other positions are pretty strong so i would take 1-2 separate smaller dishes for them where multifeeding is much easier to manage. Depends on which satellites in particular you wish to receive.

 

[Moradabad]

Channel Hopper is prodelin 2.4 M 1244 model good one for Ku band ?

 

[Channel Hopper]

The 1244 is certified at Ku band for transmit, so yes. But the original poster is using the dish for something other than that..

 

[Moradabad]

The 1244 is certified at Ku band for transmit, so yes. But the original poster is using the dish for something other than that..

I see many of the prodelin dishes have a fd ratio of .8 so which lnb best suits it..or any idea which model has a FD ratio of .6 as most of the lnb's available in market are of .6