Feedhorns with Polarotors....

Messages
12
Likes
0
My Location
Madrid
#1
I'm currently in the middle of migrating my system to include Digital, I'll detail my complete system first then I'll explain what are my current problems :

Echostar 1.2m Offset Dish
Jaeger H-H Mount
Gardiner 0.8db LNB (flange type)
Feedhorn with mechanical polarisor
Echostar AD3000IPVA
Panasonic dsb-30 digibox (sitting on the digital out of the Echostar)

OK then, my Sky access is not the best (no vertical channels, north beam drop outs etc etc), but I'm not so worried about this at the moment as I would like to upgrade my LNB and cables, then re-align my dish first, then see what I get after.

Now, the problem starts. I go to my friendly neighbourhood Satellite Shop in Madrid (Spain) and the guy sells me a MTI Dual Output C120 0.6db LNB. The idea being that the Sky Box can control the polarisation of its part of the LNB and the Echostar will control the optimum skew angle (via the feedhorn) when on 28.2E and all the other satellites the Echostar takes care of. So then, I arrive home and my existing feedhorn doesn't fit (screwholes don't match) !

Q1: Is the MTI LNB any good ? I would appreciate any other recommendations.
Q2: Am I right in thinking there are two types of flange LNB's C120 and WR75 ??

So, I ask the shop to get me a new feedhorn with integrated polarotor that is suitable for my dish. And, well, to cut a long story short, they can't get one, nor can the next shop or the next shop......
Therefore....

Q3: Can anyone tell me where I can get a feedhorn with polarotor to fit a C120 type flange ?
Q4: Do I just make an adaptor and hope for the best ?

Or shouldn't I worry about the skew functionality anymore (the whole reason for having a polarotor in the first place) and just bolt on a LNB with integrated feedhorn ??

Any feedback would be highly appreciated..

Thanks in advance
 

rolfw

Believe it when I see it Admin.
Staff member
Messages
37,689
Likes
1,283
My Satellite Setup
Technomate 5402 HD M2 Ci, DM7000s, Transparent 80cm Dish, Moteck SG2100 DiseqC motor, lots of legacy gear. Meters: Satlook Digital NIT, Promax HD Ranger+ spectrum analyser.
My Location
Berkshire
#2
I'm afraid I don't have the answer to your question on the flange compatability, but certainly there are many successful H to H users with integrated LNBs. I'm off to work now, but if you scan around there are a couple of threads on the benefits of polarotors which may help.

Rolf
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
24,905
Likes
5,490
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
#3
Since the C 120 LNB has the polarisation sorted out by the use of the 13/18v line, the flange holes are indeed different to those on the end of the feed polariser, which are designed to connect to a single polarity or WR 75 LNB

If the feed cannot be removed from the polariser part then you havetwo options, either change the feed completely, and put up with a possible mismatch to the dish, or send back the C 120 LNB and swop it for a good noise single polarity dual band LNB. These are now cheap and still perform better than the best low noise Universals. You will have to use the Echostar to change polarity on option 2
 
Messages
12
Likes
0
My Location
Madrid
#4
Still find it difficult to believe that these feedhorns are so hard to come by. I thought that the skew functionality was an absolute necessity with a movable dish....... oh well.

However, I have managed to find an adapter plate from IRTE for WR-75 to C120 on a german website (www.rochegmbh.com/preise/p_feeds.htm), so I'll have to remember some german and give them a bell, I'll let you know how I get on.

Anyway, thanks for the input.
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
Messages
24,905
Likes
5,490
My Satellite Setup
A little less analogue, and a lot more crap.
My Location
UK South
#5
You cant go from WR75 to C 120. Since the opposite polarity has already been removed, it would be impossible to re-introduce it

A mechanical polariser in your system would already have the WR75 conversion done for you without more equipment
 
Top