can you scan too much?

[icstephen]

Ok forgive me if this is a dumb question but I don't know a whole lot about these lnbf's, But I am thinking back to my C-band days and I used to wear out my polarotor like once a year. I really like to look for feeds and I have blind scanned 4 or more times in a day and I was wondering if I am putting any undo wear and tear on my lnbf or receiver?

 

[Mr Tony]

nah. I've been scanning the skies with my Pansat for 3 years now with no issues

polorotor is different as the skew kept moving as you switch polarities. The new LNB's have a notch for both V & H polarities in it so you're nto burning anything out

 

[icstephen]

Awsome...thanks Ice, I figured it would be ok but I am very inquisitive about these things.

 

[123tim]

I am thinking back to my C-band days and I used to wear out my polarotor like once a year.

So, does this mean that the old LNB's had a mechanical mechanism to change polarity?

 

[Mr Tony]

yes Tim

The C-Band LNB's have one "stick" inside, whereas the new ones have 2 that are 90 degrees apart.

I learned that when working on my C-Band project..when you change channels (polarities) the "stick" moves inside. Thats why some people have "skip" setup on their C-band dish so it goes
1,3,5,7,9 etc to 23 then 2,4,6,8 so not to burn that out right away

The C-band LNBF I have (same with PSB, MikeI and alot of us with newer C-Band dishes) have the 2 built in so we dont burn them out. No movement inside

 

[icstephen]

when I get another C-band set up I am going to go with the dual feed horns so I can do away with the Polorotor all togather

 

[Mr Tony]

Stephen
The majority of us use the DSMI 421 C-band LNB. PSB has them (www.psbsatellite.com) You have to manually skew it but it works really good.

Tim here is the picture down the barrel of the LNB...just the one "notch", stick, etc

 

[Das Hammer]

Stephen
The majority of us use the DSMI 421 C-band LNB. PSB has them

And, 4DTV receivers (at least the 920 and 922) can use voltage to change polarity in case you have one of these types of feedhorns. Seems like some late model GI receivers could do that too...

 

[123tim]

Iceberg,
Good to know. Thanks for the picture. Makes understanding much easier.

 

[PSB]

Icebergs picture is a wee bit out of focus, here is another shot of a polarotor .....

 

[Change]

Hm, I've wondered on the feedhorns with the servo, do the tuners adjust the servo for appropriate skew on each sattelite, or do they just crank it 45 degrees either direction? Or does the movement of the dish on the polar mount take care of skew?

 

[1inabillion]

ok guys i know they make a C/Ku lnbf for buds so where can you find them

Sat Co. i checked are out of stock. what a good price?

 

[Tron]

Hm, I've wondered on the feedhorns with the servo, do the tuners adjust the servo for appropriate skew on each sattelite, or do they just crank it 45 degrees either direction? Or does the movement of the dish on the polar mount take care of skew?

The Pansats have the ability to control a polarotor, and to control skew on a polarotor. Its an adjustment that most of us ignore because we don't need it with the new LNBFs, but its nice to have just in case...

 

[Shawn95GT]

Hm, I've wondered on the feedhorns with the servo, do the tuners adjust the servo for appropriate skew on each sattelite, or do they just crank it 45 degrees either direction? Or does the movement of the dish on the polar mount take care of skew?

Yes, you can fine tune the skew per satellite. Both my Pansat and my 4DTV would do it this way.

In my setup the skew setting seems optimized at the same values for H and V at all of the positions across the arc. The interesting thing to me is that my C and Ku 'sweet spots' don't match right now. I think my dish is just a little bit off and I'm going to dial in the Ku side to get it dead on.