Low signal on New LNB

[htpc]

I had a cheap lnb on a oval 80cm horizontal 80+cm vertical dish. I sometime got no signal in heavy rain.
I though I would fix this and bought a twin output lnb to use on two receivers.
I marked the skew on the old lnb and swapped with the new. The new was very expensive, it is alot heavier and alot bigger but I don't think the arm moved from its position.
Instead my signal strength and quality going up it went down by about 20%. Now during extreme sunshine I get no signal (not an issue before) and sa soon as it's cloudy/the first rain drops I get no signal.

What am I doing wrong? The lnb is quality so is my cable & my install. Is the oval dish the problem? Do I need to move my dish vertically & horizontally & re-adjust the skew for the new lnb? I tried re-adjusting the skew only but could only make it worse. Does the cheap dish like a cheap lnb better?

[dick b]

If you have a standard 80cm dish it should have been installed with the longest side vertical,what make is it? cheap lnbs are usually ok I"ve got one I bought from Lidl for ?4 and its fine.
It sounds like your dish setup needs completely re-doing as neither sun nor even moderately heavy rain should affect the signal on all but the weaker channels.
If the lnb is mounted centrally in the holder with the F-plug pointing down you will get good enough results although fine tuning may improve it.
you can adjust the elevation (up & down) and azimuth (side to side) to get maximum quality on the signal bar,but if you can get a cheap meter it will be better.

( and no your dish wont favour either lnb)

[htpc]

dick b,

longest side is vertical as you say, I have no idea what make it is, it came with the install. The slightest rain & very strong sun all channels lose signal on both receivers. I only replaced the lnb, nothing else. The lnb is mounted centrally in the holder with the F-plug pointing down as you say. Thanks about the elevation (up & down) and azimuth (side to side) I never realized what they were until now. Also good about the lnb being compatible.
I will try to do it without a meter first to save some cash. I will bring a receiver & a monitor on the roof and while moving the dish I will watch for the signal strength & quality. Is this the way to do it? First elevation, then azimuth, then skew? I'm still learning, bear with me.

[terriers]

m8..you havent told us wether its a fixed dish on one particular sat or a motorised install!!

[htpc]

Yeah sorry it is a fixed dish on one satellite only, it doesn't get any simpler. Not sure what's wrong, I will have to fine tune it, if it doesn't work I will have to buy a bigger round dish.
EDIT: The new expensive lnb is an Invacom 0.3db if it makes any difference. The old cheap one that worked fine I have no idea.

[terriers]

what sat u on m8 cos 80cm should suffice for most sats available to the uk!
also your location would help..

[.: JaCkPoT :.]

Different lnbs have different pure skew points. Dont rely on your old skew. Just play around till you hit peak signal.

[htpc]

I'm in Cyprus, Hotbird 13E, I've played with the skew, still 20% down on signal strength/quality I barely make 40-45% signal strength. Before it was over 70%. I think new lnb & old dish don't mix. I will say for sure when I try moving the dish, haven't done this yet. The dish is 80cm horizontally but vertically it is longer.
This is the lnb:
TWH-031 (http://www.invacom.net/products/twh031.htm)

[opsmonkey]

this is a LNB for a prime focus dish (like this one)

http://www.galaxy-marketing.com/prime-focus-c-band-dish.jpg


.. do you have one of those or do you have a dish like the one below..?

http://simplyaerials.co.uk/shop/images/orb1.jpg

[htpc]

My dish looks exactly like the one at the bottom. Can you explain what's a prime focus dish just out of curiosity?
I see the top dish is made of several parts (cheap but difficult to setup?). The lnb at the top doesn't have an integrated feed horn like the bottom dish or mine infact. Can you explain when to use one or the other and why? Thanks, sorry if off-topic.

[SatSearching]

I'm in Cyprus, Hotbird 13E, I've played with the skew, still 20% down on signal strength/quality I barely make 40-45% signal strength. Before it was over 70%. I think new lnb & old dish don't mix. I will say for sure when I try moving the dish, haven't done this yet. The dish is 80cm horizontally but vertically it is longer.
This is the lnb:
TWH-031 (http://www.invacom.net/products/twh031.htm)

It sounds like an offset dish if the reflector is taller than it is wider, is the lnb you bought for an offset dish and not a prime focus? Did you have to "bodge" the lnb mounting a bit to make it fit?

EDIT: Ok, just looked at the link for the lnb, I think I used to have one of them, I seem to remember the body is confusing and the lnb body is 45' out to what you may think, use a meter and give it a good skew. Do you also have room to move the lnb forward and backwards a bit to adjust to the best focal point?

[opsmonkey]

if you have a dish like the one at the bottom then the lnb you need looks like this..

http://www.dvbdirect.com/images/products/invertosingle.jpg

[htpc]

I have found an old image of my old lnb and resized it at Resize your image online - It's easy, it's free! (http://www.resizeyourimage.com/)

Yes my dish is offset, it is taller than wider, I don't have a pic of it, (pic of lnb was closeup).

I didn't have to bodge. It fit the same as the old one but I have a few mm of travel to adjust the focal point and I've tried this but didn't seem to make any difference (you couldn't move the old lnb, it's "neck" had no room to move). The new lnb is huge and might be sitting at a slightly different distance from the dish. When I bought it I took a picture of my old lnb (see above) and ordered one from the net that looked like it.

opsmonkey,

what are those vertically looking lnbs for, do they serve a different purpose?

[opsmonkey]

no they are just a different shape..

to help un-confuse yourself think of it as this..

2 types of dish..
1 is prime focus.. 1 is offset dish
Each has it own type of LNB

Although they are both satellite dishes they require different bits of hardware..

In the same way VHS and Betamax were Video Players but you couldnt use a VHS tape in a Betamax player and vice versa..

You are using the wrong type of LNB for your dish hence the crap reception

Go to here..

http://www.satcy.com/lnb.htm

and order either the:

"Inverto single LNB 0.3 for ?15"

or the

"Maximum Digital Technology single 0.3 dB for ?12"

[htpc]

opsmonkey,

I'm still confused :embarassed:

Tell me where I am wrong.

1) There are two types of dishes prime focus (round) & offset (oval). I don't know when to use one and when the other.

2) Prime focus dishes use lnb with "separate" feed horn while offset dishes use lnbs with integrated feed horn. Is this even correct?

You said the correct lnb for my dish is Inverto single LNB 0.3. Is this model no. SNH-031? If so it looks like the one I've bought except mine is twin output (TWH-031). I don't get why it is the wrong type?

Invacom.net Low Noise Block, converter, Invacom, Universal, DBS LNB, 0.3dB, single, SNH, SNF, twin, TWH, TWF, quad, QDH, QDF, quattro, quatro, QTH, QTF, 40mm Horn, C120, high performance, quality, receive satellite TV and KU Band Transmitter, VSAT PL (http://www.invacom.net/invacom_products.htm)

P.S. I've tried reading some satellite faqs but can't seem to find the answers I want.

[opsmonkey]

just because something 'looks' like another it doesnt mean its the same.. to the untrained eye anything can look 'similar'..

dont buy an Invacom one as they are prime focus LNB's mate..

The difference between the offset satellite dish and prime focal (prime focus) dish is the way the signal reflects from the surface and where it gets concentrated.

Prime Focus Dishes, the signal reflects from the satellite dish and concentrates towards the center, where the LNB is mounted to catch the signal.

Offset Dishes are designed with an offset angle. Usually set at 21-degrees. With this design, the signal reflects from the dish and concentrates towards the bottom of the satellite dish instead of the center of the satellite dish..

You need different types of LNB for each type of dish

[htpc]

Finally I get it! thanks for sticking with me.
You suggested an Inverto and I read that as Invacom. (sorry long day) That's where the confusion came from. I finally understand the difference between the two dishes.
Damn Invacom websit not being newbie friendly.

[opsmonkey]

no probs mate.. when ordering again just make sure its the correct LNB for your type of dish..

Most dishes in Cyprus that i came accross were massive Prime Focus ones in excess of 3m.. hardly saw an Offset, unless it was a BFBS Dish on base lol

[htpc]

The dishes are over 3m by necessity, sky uk is pretty far away!
The offset dishes are the ones that come as standard with the cypriot packages such as mine.
I had to bring a ladder and go on the roof just to make sure my dish was oval. Before today I could have sworn it was round.

[dick b]

If you go onto this retailers site you can browse through their stuff and look at loads of lnbs and dishes it will give you some idea of whats available. satellitesuperstore.com (http://www.satellitesuperstore.com)

[wod1]

also did you move the lnb forward and back in the collar to get the best position for the lnb as that will help and then skew the lnb.

[htpc]

If you go onto this retailers site you can browse through their stuff and look at loads of lnbs and dishes it will give you some idea of whats available. satellitesuperstore.com

that's where I got it in the first place, there is no mention that it's only for prime focus not offset dishes:(


also did you move the lnb forward and back in the collar to get the best position for the lnb as that will help and then skew the lnb.

yes I moved it the few mm it was able to move & skewed it as well, no improvement

[.: JaCkPoT :.]

Invacom do indeed manufacture lnbs for offset dishes. I have a price list here from a wholesaler and Its in there.

[dick b]

hello again mate,
I have seen pictures of invercom TWH-031 lnbs on offset dishes but it seems they are difficult to set up and they are low output and require a short cable run 20mts max.I still feel your main problem is the dish adjustment it needs setting up with a meter.I"d go back to your original lnb re-set the dish then put a cheap quad lnb on and put the invercom down to experience if you cannot get it going.
when it comes down to it its dish size that is the main factor in reception you really dont need an expensive lnb.

[satsid]

just because something 'looks' like another it doesnt mean its the same.. to the untrained eye anything can look 'similar'..

dont buy an Invacom one as they are prime focus LNB's mate..

The difference between the offset satellite dish and prime focal (prime focus) dish is the way the signal reflects from the surface and where it gets concentrated.

Prime Focus Dishes, the signal reflects from the satellite dish and concentrates towards the center, where the LNB is mounted to catch the signal.

Offset Dishes are designed with an offset angle. Usually set at 21-degrees. With this design, the signal reflects from the dish and concentrates towards the bottom of the satellite dish instead of the center of the satellite dish..

You need different types of LNB for each type of dish

Iv a Invacom on a off set dish with c120 feedhorn.I find mine works great,as signel hit the edges of the dish.

[SatSearching]

Agreed, saying "dont buy an Invacom one as they are prime focus LNB's" is confusing as they do make offset LNB's, I had one on my offset dish.

I fully agree though that offset dishes is Cyprus is very rare, most are prime focus, actually I am surprised to read this post that a user in Cyprus is using an offset dish!

SS

[mkgigs]

Prime focus dishes are used for larger dishes now a days as the shape makes for a strong dish. Off set dishes will only usually be made up to about a 1.8m size.The off set dishes are basicaly a section taken from a larger prime focus dish and the focal point of it found. I used to be involved in the manufacture of dishes in the late 80s to mid 90s working for polar cold and levicks dishes.

[opsmonkey]

Agreed, saying "dont buy an Invacom one as they are prime focus LNB's" is confusing as they do make offset LNB's, I had one on my offset dish.


sorry i should have clarified a bit better.. what i meant was dont buy one of the site i linked (satcy.com) as they are for prime focus dishes only..