Invacom + Andrews feedhorn

[jtkeep]

Changed my old Digitality SF1, with a Quad Invacom c120 and Andrews feed horn on my 120cm offset dish.

This did not give me any improvement about 30% signal quality, also signal strength went down from about 60% to about 50%.

I tried all different positions on feedhorn but could not get any big improvments.

Any sugestions would be welcome.

All the best and a happy xmas to you all

Thomas

 

[koansrc]

Do you know the f/d of your dish and the f/d of the feedhorn ? Is the feedhorn adjustable ?

 

[hoppo1]

You want a standard LNB on an offset dish not a C120, they are for prime focus dishes. Are you using it because you can't get a standard (40mm) LNB in the bracket?

 

[jtkeep]

Hi guys thanks for your replies, i dont know the f/d of the dish sorry.

The Andrews feedhorn is made for offset dishes not for prime focus dishes,
and you must use C120 lnb for the Andrews offset feed horn.

I am coming to the conclusion that i was lucky with Digiality SF1 and it was very sensitive for the 10773 H frequency, i tried many makes of LNB at the time to find the best one.

The only problem i have is since i moved 100km further north here in denmark the signal has dropped from about 50% to about 30% on 10773 H, and i have problems with ITV meridian 10891 H in the mornings until about 11 it pixelates.

So i thought the Andrews feedhorn plus Invercom Quad would just give me last few % to get the ITV Meridian clear in the mornings.

All the best Thomas

 

[dxsat]

Just for the record, C120 LNBs are suitable for both offset and prime focus dishes.
The Andrew Feedhorn mentioned is only for offset dishes and is not adjustable.

Which type of dish you have? If not an Andrew/channelMaster, some adjustments have to be made to get the optimum focus. Can you post a few pictures here? This should enable a full diagnosis of the problem. Just go advanced and upload some attachments.

Possible causes for worse performance:-
Focus point not correct.
Packing on LNB holder not right, packing necessary on some non- Andrew dishes, could be too high/too low/not pointing right.
"O" ring between LNB and feedhorn not correctly located.
Small object fallen into LNB. (I did this once)
Bridging on braid and inner conductor inside 'F' connector. A single strand will not stop things working but will degrade performance. (I've also done this a few times)
Skew not correct.
Dish may need fine adjustment with new LNB and feed after change over. Typically a few mm adjustment may be necessary.

A correctly set up Quad Invacom and Andrew Feedhorn will always give a better result than a LNBf on dishes larger than 120cm in fringe Astra 2D areas.

 

[hoppo1]

Nice post, Snap.
I didnt know that a C120 was used for these.

 

[jtkeep]

Hi Snap here are a few pics of the setup if its not enough i can take more.

all best Thomas

 

[hoppo1]

What sat are you after?
I am an idiot! I forgot it was in the Astra fringe reception section:-slaphead:-pointer
I think you will want more skew on the lnb, turn it to the right (as you look from the front) so that the top is at about 10 oclock.

 

[jtkeep]

Hi Hippo i am receiving Astra 2D BBC ITV mostly, i have tried the skew in both directions just made the signal weaker.
Mostly i have reception 24/7 365 except in heavy rain and snow.
Only problem is ITV Meridian in the mornings, just need 5% more signal then all will be great, thought the new feedhorn LNB set up would give this.

Also snap can i put a Chanel Master 120 dish on the bottom of the wall pipe as i have now in picture with my present dish, think about buying a
Chanel master 120.

All the best Thomas

 

[koansrc]

Set up looks ok I guess. For Copenhagen the polarization angle should be -3d, so that's a very slight twist of the lnb to the right (looking at the dish). 3d is only about half a minute of a clock. I suppose you've tried the different outputs of the quad and so I guess we wait and see what "adjustments" Snap will suggest for the feed.

From which freq are you getting your quality and strength readings ?

 

[jtkeep]

Hi Koansrc mostly i use 10773 H as a measure frequency mostly the Verticals on 2 D are 10-15% higher than the Horizontals, the weakest frequency i have is 10891 H-

On my Pace 2600 the 10773 H shows quality and strength readings about middel on the meter quality 50% strength 60% a little lower in the mornings 30% quality 50% strength.

All the best Thomas

 

[dxsat]

Hi Thomas, thanks for posting the pics. The dish does not look like a 120 cm, more like 100 or 110 cm. (measured horizontally- this is the standard way) This will be the reason for no improvement over the previous LNB. It's only worth installing an Andrew feed on dishes larger than 120 cm. Unfortunately, you will have to find a thicker mount post, as the ChannelMaster/ Andrew 120 cm has a 3" (or 75 mm) socket. This is essential owing to the extra weight and wind shear compared to what you have.
Skew looks correct, should be -3.42 degrees. (Based on Copenhagen, you don't give exact location)
You could try moving the LNB and feed backwards so the feed sees more of the dish, the focal length of the dish may not match the feed in its current position. (This is a common problem with this feed)
The good news is that if you fit the ChannelMaster you should see a significant improvement. A ChannelMaster and Andrew feed on a ChannelMaster dish, well tuned with zero point error will give roughly the same performance as a 1.5m Gibertini with a cheap LNBf.

 

[jtkeep]

Hi Snap
I think you are right the dish is 105 cm x 115 cm that would make it a 110cm dish.

The thing is i moved 100km due north here in denmark Jutland, i took the dish and LNB with me to new house, in the old house i had on my Humax receiver about 45%-50% signal quality. useing same dish LNB in new house i only get 30% signal quality.

I did some fine trimming today i am now getting 36%-38% on the invercom quad andrews feedhorn, this is useing the humax and on 10773 H.

I will be looking for a Chanel master 120 dish now, can this dish only be mounted on a metal post on a flat roof, or can it not be mounted on a simular metal pipe as in the picture maybe a larger pipe 75mm.

All the best Thomas

 

[dxsat]

You can use a wall mount like the two images attached here. The one with the arms is very stable but really difficult to get perfectly vertical.
It's also undersized by 5mm but you can get away with this on a ChannelMaster dish.
These are both from Tecatel in Spain, I think they have distribution in other countries.
You can get non- penetrating mounts for a flat roof, they are posts with a large framework weighed down by slabs. Quite expensive solution unfortunately.

 

[jtkeep]

Hi and thanks Snap for your very interesting info on this Ivercom+Andrews feedhorn.

I have as i said tweaked as well as i could useing a Humax as a sat meter it has a very good meter in %.

I have now the channel on 2D which was weakest on my system and pixellelating10891 H it is now clear even in the mornings so the Invercom+feedhorn helped.

For my next moves i will loan a sat meter and try to tweak even more , and i am planning to buy a Channel Master 120 dish, that will be the ultimate system, cant get better.

A very happy new year to you all.
Thomas

 

[agil]

Were can i buy Andrews Feed Horn
See the photos above
Thx

 

[dxsat]

Satellite Superstore ( worst website in the western world) sell them, if you can find the right page.

 

[milch]

@ snap

Hi snap,

I´m thinking of trying to receive Astra 2D in Berlin with a 1.8 m prime focus dish mounted onto a wall. How practical are wall mounts for a 75 mm mounting post?

milch

 

[dxsat]

Not really practical at all. The only way you can get away with mounting a dish this size on a wall is in a protected site, say in a yard or not exposed to high winds.
The 75 mm wall mounts commercially available will not cope with the wind shear on a 1.8m. You'd have to get something made specially, with outriggers or fit it with guy wires strained really tight with turnbuckles. You also have to be sure the wall is strong enough as a weak one could be demolished in a gale.
Use chemical bolts.