Got a C-Band dish...now some questions

[voomvoom]

Tony, I had a simular problem a few years back, when I replaced a servo motor. They only turn so far in either direction, come to find out I had put it in with it turned all the way to one side. So when I changed channels, I got good reception on one polarity and crappy on the other. i didn't know what was going on, all I knew was the only change I had done was replace the servo motor. I took it off and watched it by site as I changed the channel and it moved, but it only moved 90-100 degrees. I got to playing with it and noticed I could turn it with my finger further in the opposite direction than it was turning on its on. I eventually figured out if I put the receiver on the channel (polarity) that had been working, I could move it to the correct position and it worked right. I put it back on the feedhorn and it's been working since.

Al

 

[WyrTwister]

tomorrow I'll take pictures

crap so the top 1/2 of the dish must do one polarity and the bottom 1/2 is the other polarity?

I am far from an expert , but I do not think so ?

Wyr

 

[WyrTwister]

Tony, I had a simular problem a few years back, when I replaced a servo motor. They only turn so far in either direction, come to find out I had put it in with it turned all the way to one side. So when I changed channels, I got good reception on one polarity and crappy on the other. i didn't know what was going on, all I knew was the only change I had done was replace the servo motor. I took it off and watched it by site as I changed the channel and it moved, but it only moved 90-100 degrees. I got to playing with it and noticed I could turn it with my finger further in the opposite direction than it was turning on its on. I eventually figured out if I put the receiver on the channel (polarity) that had been working, I could move it to the correct position and it worked right. I put it back on the feedhorn and it's been working since.

Al

I think that is why I was told to put the polorotor at 10:30 on due south . To keep the polorotor in the midrange of it's operation .

I have my ( motorize system ) set so the skew goes from + 45 to - 45 . Except for the far extream east and west .

Wyr

 

[Mr Tony]

Tony, I had a simular problem a few years back, when I replaced a servo motor. They only turn so far in either direction, come to find out I had put it in with it turned all the way to one side. So when I changed channels, I got good reception on one polarity and crappy on the other. i didn't know what was going on, all I knew was the only change I had done was replace the servo motor. I took it off and watched it by site as I changed the channel and it moved, but it only moved 90-100 degrees. I got to playing with it and noticed I could turn it with my finger further in the opposite direction than it was turning on its on. I eventually figured out if I put the receiver on the channel (polarity) that had been working, I could move it to the correct position and it worked right. I put it back on the feedhorn and it's been working since.

Al

Al I'll have to see that but the servo motor should turn the skew bar (there is only one in there) 180 degrees?

my Toshiba goes form 0-80 for skew so that may be it.

 

[Mr Tony]

I think that is why I was told to put the polorotor at 10:30 on due south . To keep the polorotor in the midrange of it's operation .

I have my ( motorize system ) set so the skew goes from + 45 to - 45 . Except for the far extream east and west .

Wyr

I'll have to try that...I have to take the screw out and rotate the LNB but I should be able to do it

 

[Mr Tony]

OK..here is answers to some questions

-I can't take pictures because its dark out. I tried to look up at an angle from the LNB and it looks like the bottom 1/4 is blocked (damn)
-The skew adjustment on the Toshiba goes from 0 to 80
-The little skew thing in the LNB goes almost 180 degrees.....Is that fine or should it go more?
-when the skew is at 45 in the Toshiba, the LNB/downconverter/polorotor is at 12:00/6:00
-I get channels 15, 16 & 17 analog really good. 15 & 17 are H and 16 is V

The polarities are right but is there any way if I turn the LNB another way I can get H polarity better?

 

[voomvoom]

Tony, I would try it and see. You have nothing to lose and it might help. If not, you can always move it back.

Al

 

[Mr Tony]

Like I mentioned before, here are my results when I scan the arc (analog)

-G4 I get V, H sucks for digital (analog I get both)
-IA5 I get H good, V sucks
-G3 I get V good, H sucks (get some low signal V digital TP's, none on H)
-IA6 I get H good (PBS comes in with minimal sparklies), V sucks

Havent tried AMC4 yet but by the looks of it, I might get NBC (they're Horizontal) but nothing else (all vertical)

I'll try the turning the LNB 90 degrees but all I think is the polarity will be screwed.

I honestly think 1/2 the dish does H and 1/2 does V and thats why I get alternating polarities as I move across the arc.

More work tomorrow plus pictures

 

[ftarock]

I honestly think 1/2 the dish does H and 1/2 does V and thats why I get alternating polarities as I move across the arc.

Dish is a refector, that just gathers the signal. Skew/polarities has nothing to do with dish. That's how the rotor is for, changing the skew.
FtaRock

 

[WyrTwister]

Al I'll have to see that but the servo motor should turn the skew bar (there is only one in there) 180 degrees?

my Toshiba goes form 0-80 for skew so that may be it.

Yes , there is just one probe that rotates .

Best I remember , it should rotate at least 180 degrees , That will allow you to hit H & V , no matter what .

But if you had everything set perfect , it would only have to move 90 degrees .

Wyr

 

[WyrTwister]

OK..here is answers to some questions

-I can't take pictures because its dark out. I tried to look up at an angle from the LNB and it looks like the bottom 1/4 is blocked (damn)
-The skew adjustment on the Toshiba goes from 0 to 80
-The little skew thing in the LNB goes almost 180 degrees.....Is that fine or should it go more?
-when the skew is at 45 in the Toshiba, the LNB/downconverter/polorotor is at 12:00/6:00
-I get channels 15, 16 & 17 analog really good. 15 & 17 are H and 16 is V

The polarities are right but is there any way if I turn the LNB another way I can get H polarity better?

You are on G 4 ?

The even are one polarity , the odd are the other polarity .

Try setting it on a H channel & with a TV at the dish, rotate the feedhorn to tweek the picture .

Wyr

 

[WyrTwister]

Like I mentioned before, here are my results when I scan the arc (analog)

-G4 I get V, H sucks for digital (analog I get both)
-IA5 I get H good, V sucks
-G3 I get V good, H sucks (get some low signal V digital TP's, none on H)
-IA6 I get H good (PBS comes in with minimal sparklies), V sucks

Havent tried AMC4 yet but by the looks of it, I might get NBC (they're Horizontal) but nothing else (all vertical)

I'll try the turning the LNB 90 degrees but all I think is the polarity will be screwed.

I honestly think 1/2 the dish does H and 1/2 does V and thats why I get alternating polarities as I move across the arc.

More work tomorrow plus pictures

Most of the sats will be of reverse polarity , to the sat directly east and directly west of it .

So , TP # 1 may be V . The sats on either side will be H on TP # 1 . Or vice Versa .

The digital will be much more sensitive to shew , elevation & east - west tweeking . If the dish is large enough to give strong signal , analog is much more tolerant of mis-alignment .

Wyr

 

[Mr Tony]

You are on G 4 ?

The even are one polarity , the odd are the other polarity .

Try setting it on a H channel & with a TV at the dish, rotate the feedhorn to tweek the picture .

Wyr

Yep on G4. Get the 2 church channels. Analog Channel 15 is H polarity (World Harvest) and comes in really good and CHannel 16 is vertical (Shepards Chapel) and comes in good too. The digital stuff on V comes in with a good quality (between 45 and 60) but the Horizontal is squat.

I am using the TV theory. TV is about 10 feet from me with both analog & digital setup.

So I shuld rotate the feedhorn and not try and skew it?

 

[Mr Tony]

Most of the sats will be of reverse polarity , to the sat directly east and directly west of it .

So , TP # 1 may be V . The sats on either side will be H on TP # 1 . Or vice Versa .

but whats weird is on G4 V stuff comes in fine, but if I move to T5 Horizontal works. Move to G3 and V works again. Its like it only want to work with one polarity and not both. I'll try the other LNB I have here (the one you have tro manually skew)

analog is much more tolerant of mis-alignment .

Wyr

found that out right away

 

[Mr Tony]

Pictures

1st one is my C-Band setup. It has the DMSI LNBF on it
2nd one is closeup of LNB. It has to be turned 90 degrees to work right
3rd is what I am using to tune..TV/Pansat 1500/Toshiba 1420
4th is a closeup of the skew and how it has to be 90 degrees off
5th is a wideshot of my LOS issue

I did some measuring and it isnt good
6th, 7th & 8th are where I feel the signal cuts off due to the roof (anything below the stick)

I tried the DMSI and had a couple issues so I went back to the LNB with the polorotor and hooked up the wires

9th-12th are the analog results. As you can see I get both H & V analog

last 5 are digital results. I blacked out the frequencies & symbol rates because these are feeds (but they are listed on Lyngsat)
As you can see, Vertical I get good results but H I can only peak at a 15. I'm going to keep working on it but here is some progress. H has very few sparklies on analog (maybe 3 or 4 that I can see)

 

[PSB]

Yes, it looks like only less than half of your dish is getting signal. The dish needs to be higher by about 4-5'

Thats your problem!

Amazing pictures THANKS!

 

[Mr Tony]

Thats what I figured (Pete it's more than 1/2...below the stick has LOS issues..that was using about 40 degrees as a standard)

Might have to go to hardware store and get some longer pieces of pipe

but why can I get great quality on V but squat on H? If I move to IA5 then the polarities are flipped and H comes in great but V sucks...It just doesnt make sence

 

[PSB]

Maybe the way the signals come down, H / V

With the H polarity half the dish is blocked period.

The V polarity signals are maybe able to see or bend into the dish and give you better signal? (Guess)

Anywho when you go higher the problem should go away! (I hope.)

 

[PSB]

The LNB seems to have dropped slightly I would pack it so that its exactly square to the dish and the scalar ring. Should bring you slightly more signal quality.

 

[WyrTwister]

Pictures

1st one is my C-Band setup. It has the DMSI LNBF on it
2nd one is closeup of LNB. It has to be turned 90 degrees to work right
3rd is what I am using to tune..TV/Pansat 1500/Toshiba 1420
4th is a closeup of the skew and how it has to be 90 degrees off
5th is a wideshot of my LOS issue

I did some measuring and it isnt good
6th, 7th & 8th are where I feel the signal cuts off due to the roof (anything below the stick)

I tried the DMSI and had a couple issues so I went back to the LNB with the polorotor and hooked up the wires

9th-12th are the analog results. As you can see I get both H & V analog

last 5 are digital results. I blacked out the frequencies & symbol rates because these are feeds (but they are listed on Lyngsat)
As you can see, Vertical I get good results but H I can only peak at a 15. I'm going to keep working on it but here is some progress. H has very few sparklies on analog (maybe 3 or 4 that I can see)

I would put it on H on digital & tweek the physical rotation of the feed horn , with the toshiba set to 45 , just as an experiment . Then see what it does on a V channel , with the Toshiba set for 45 .

Maybe , if you have enough time and favorable weather , do the same with the LNBF ?

Only a few sparkles on 15 & 16 analog may be about as good as you can get at the present location of the dish ?

Can you take some pics of the base ?

I agree , the dish needs to be a little taller . But from what little I can see of the base , I do not know how a convential pipe / pole will work on your dish .

When you get all this working , you really NEED to paint that scalar ring ! The die cast look makes the rest of the dish look something a little less than professional .

Best of luck ,

Wyr