Splitting H and V channels over 2 dishes?

[wallycharlo]

I'm living on the fringe of the 2E / 2F UK beam, and have noticed that I can get a noticeable improvement in reception of channels of one polarization by skewing the LNB, though at the disadvantage of then weakening those on the opposing polarization. Hence the following mad idea has occurred to me:

Can a system be setup where I take the H channels from one dish, and V from another? i.e. I set the skew on both dishes to give maximum reception for that particular polarization. Is this somehow possible with some type of Diseqc setting etc I wonder?

Thanks & Regards ... Wally

 

[Steve Steve]

Hi wally....you will need a multiswitch and 2 Quattro LNB's.....to make your plan work...........on one Dish...the horizontal high & low output...and from the other Dish the vertical Low & high outputs ..conecteted to a multiswitch.....good luck....

 

[PaulR]

Maybe with DiSeqc - I'd have to think about it.

But the easiest (!) way to do it would be use a multiswitch/quattro (must NOT be quad) LNB combination. You could easily (again that word) put the feeds for the HL and HH to one dish and VL and VH to the other.

In the past I have idly mused about doing similar in a fringe area to avoid overloading of signals. Low band frequencies would be on a humongous dish for the spot beam and a normal sized dish for high band european frequencies as this mostly how it goes. never got around to it as I didn't suffer from desensing in France.

If you have enough time/money/madness how about four dishes for each variation?

 

[timo_w2s]

You could do it with DiSEqC and standard LNBs too, just pretend that they are two different satellites in your receiver and choose the strongest signals from either of the "satellites," depending on which is optimised for H and the other for V.

(Edit: Assuming you are not using Sky or Freesat boxes)

 

[hexah]

I'm living on the fringe of the 2E / 2F UK beam, and have noticed that I can get a noticeable improvement in reception of channels of one polarization by skewing the LNB, though at the disadvantage of then weakening those on the opposing polarization. Hence the following mad idea has occurred to me:

Can a system be setup where I take the H channels from one dish, and V from another? i.e. I set the skew on both dishes to give maximum reception for that particular polarization. Is this somehow possible with some type of Diseqc setting etc I wonder?

Thanks & Regards ... Wally

This is yet another example of de-evoloution in the digital era.

In the olden days last century we had adjustable skew from the remote control using polarotors. Loosing them is a backward step for receiving weak satellites.

The answers given are entirely sensible.

A multi-switch allows signals around the house and they and quattro LNBs are cheaper on the continent than here. You can even get them from amazon.de if that makes life easier.

Timo's solution is the easy one if you don't need to pipe it around the house.

 

[rolfw]

You could probably do it with the LNB you have, plus a quattro, or even just a quad on another with a DiseqC switch.

 

[Terryl]

Why two dishes??

Just go with a much larger dish, the bigger the dish the more signal you will put down the forcing cone of the LNB, for about every 10 CM change in dish diameter you will gain about 2 to 3 dB of signal.

If you have a 1.8 now, then try a 2.7, if at a 2.7 then go with a 3.6, it all adds to the overall signal to the LNB.

If you cant go with a bigger dish then your back with the two dish idea.

 

[PaulR]

Just a thought - it may be the LNB itself that's at fault if the dipoles inside are not correctly at right angles. In the old days these dipoles were real little bits of metal that could be tweaked with a pair of pliers. Nowadays they are printed circuits and definitely not adjustable.

You could test this with another brand of LNB if you have one (or more) to hand.

 

[Trust]

Just a thought - it may be the LNB itself that's at fault if the dipoles inside are not correctly at right angles. In the old days these dipoles were real little bits of metal that could be tweaked with a pair of pliers. Nowadays they are printed circuits and definitely not adjustable.

You could test this with another brand of LNB if you have one (or more) to hand.

I think most of the recent lnb's do have real pin antenna's . see picture of a Invacom QDF 031
Just the lnb's with the flat vertical housing at the back do have circuit board antenna's .

 

[Terryl]

And some have both the pin antenna and a PC trace.

 

[PaulR]

Shows how long it is since I pulled an LNB to bits!

 

[Terryl]

He could also split it between the H and V, a little loss on both, remember this is a digital signal, we don't need every nano volt of signal we can get.


That is unless your out in the deeeeeep fringe areas of the footprint.

 

[Terryl]

That is part of a DP twin LNB, (for 110W and 119W) here is the full photo, quite a bit of stuff inside.
View attachment 65399

 

[PaulR]

And some have both the pin antenna and a PC trace.

I note that the board says R and L so presumably that means it's from a circularly polarised LNB. Is that significant perhaps?

 

[Terryl]

For the US providers like Dish, DTV and the Canadian ones like Bell yes, they are circular, but a lot of stuff in just one LNB.

This type of LNB uses "Band Stacking" to get all the R and L transponders down one coax, you can also get both satellites on one feed.


But as to the original problem, it's funny that he loses one polarity over the other, it could be a dish alignment problem, it may not be truly vertical, or the dish is cocked on it's mount.

 

[hexah]

But as to the original problem, it's funny that he loses one polarity over the other, it could be a dish alignment problem, it may not be truly vertical, or the dish is cocked on it's mount.

That's why I'm such a believer in plum lines and taking your time to get the pole straight to present the dish square to the signal.

Nice LNB photos. I had a photo somewhere of one of my ancient C120 KU band LNBs where you could see beyond the dipoles on the PCB there was a gap so any mist or fog could float up through the feed horn into the body of the LNB!

edit to add: the polarity problem can be found in fringe reception e.g. getting 28.2e in places like the Canary Islands where at times people have had to compromise the skew adjustment to suit the channels they liked the most. A second dish would help there but at 2.4m people weren't so keen. Obviously its a problem that has come and gone over the years as satellites have come to the end of their life and been replaced.

 

[hexah]

If switching is still of interest this may be of use.



This line powered 4/8 multiswitch for outdoor use may be of interest, Hama part number 00056686. Multiswitches are almost always made for indoor use.

Where the inside of a house is difficult to access or there is no roof crawlspace it is the convention to put terrestival tv amplifiers and / or splitters and the wiring on the outside of the house. This allows installers to do the same with a satellite multiswitch.

 

[wallycharlo]

Thanks a lot to everyone for your replies. The two dish solution would be preferrable to me simply because I have all of the equipment I need hanging around.All in all a bigger dish would of course be the cleaner solution, I currently have a 1m, so even going up to 1.25m may help signifigantly. I will anyway wait some time for the signal strenghts to settle, even in the last 4-5 days there has been a signifigant drop on 2E/2F UK beam.

 

[Captain Jack]

If you only have a 1m dish, then I would go for the bigger dish. Far neater, though 2 dishes will look more purposeful!

 

[hexah]

If there has been such a drop, bigger is always better, its worth being paranoid and going to a Gibertini 1.5 or maybe a Laminas GRP if you prefer, you can get a heater for that if you are up a mountain.

If its a through-the-roof mount which is common in that part of the world, a 2m might result in the entire roof being blown off.