Scalar Rings

[bpalone]

A couple of questions.

1.) When replacing a C Band LNB, should you replace the scalar with the one that comes with the LNB?

2.) Is there anything going on with the Alaska Mux on 137? I can get the radio stuff over on 139 with a decent Q and I get stuff on 135 with a decent Q, so thought I would ask the question if it was me or not. This why I'm seriously considering taking my cheapo combo C/Ku LNB off and putting up my Titanium C1/PLL. Was holding it for when the cheapo croaked, but thinking maybe I should make the cheapo a standby model.

Thanks in advance.

 

[KE4EST]

1. Normally the one that came with the dish or Feed Horns from years ago are better made. No you don't have to, totally up to you.
2. When installed properly you definitely see an improvement with the C1-PLL. On very strong transponders not so much but it will help to pull the weak ones out.

 

[Lone Gunman]

Agree with ke4est on the scaler rings as the new ones that come with the LNBFs are really cheap junk IMHO. I really like the quality of an old Chaparral Corotor scaler ring.

3760 on 137W is OK here in Virginia

 

[KE4EST]

Thanks Lone Gunman for commenting on the Alaskan Mux, I totally left that out of my reply.

 

[T134]

I have a bit of a differing opinion or ideas.

Having sold and dealt with many different LNBF and feed types I've seen differences in scalar designs. If my crappy memory serves (at least when I was offering them) even a BSC421 and a BSC621 had slightly different scalar designs. A more drastic example would be going to an old BUD and pulling the scalar off. Those aren't designed anything like what has came with modern LNBFs.

My thought, at least in an ideal world with a quality LNBF, is that that scalar that comes with the LNBF is designed/tuned to work best with that LNBF. Do agree with Michael, I've seen the build quality of scalars drop in the toilet in only a few years. Originally they had some iron in them, now I think it is all China soft metal mixed with lead LOL. The physical design per unit seems the same though.

I am thinking especially with an old school BUD with an old scalar on it that if you throw in a modern LNBF on the original scalar there is going to be a cost or benefit with using old different design scalar with new LNBF.

This is "theory" to me as I haven't sat with 10 different scalars and 10 different LNB/feed setups and done testing. Has anyone actually put a LNBF in a different design scalar then swapped for the one that came with the LNBF and noted the differences?

The one guy offhand I can think of that might have a hand-on answer would be Brian @ Titanium Satellite. If he sees this thread and reports he has tried this 3 different ways I'd take it as gold.

 

[Magic Static]

My main concern with a scalar is that holds the LNBF straight and true to the dish. The cheaper scalars fit poorly on the LNBF. The old Chaparrals seem to fit better.

 

[bigg t]

I agree with Magic Static. After cracking the scaler that came with my Bsc-621 I found a scaler off of an old H-V controlled lnbf from around 1990 I'm guessing. It was made a lot better and also fit the newer lnbf a lot better too. The numbers I'm seeing now are at least as good if not better than the original scaler. I repaired the cracked scaler so I could put it back if I had to with jb weld.

 

[FaT Air]

Another name for a scalar is a 'choke plate' because it's nothing more than 1/4 wave RF chokes. Signals coming in from an angle get 'trapped' in the 'grooves' and do not enter the feed throat. The higher the angle, the more they are trapped. The more grooves the higher the attenuation from signals from the sides. (Higher "Q")
BTW-FWIW they are also used in your microwave oven door to prevent RF from entering the 'living space'

 

[. Raine]

You could try both and see which works best, that's what I did. Both worked about the same for me but I ended up using a Chap scalar I had rather than the new one because it was easier for me to adjust it and keep the LNBF straight with the Chap.

 

[bpalone]

Thanks for the responses. I switched it out and used the scalar already on the dish. Can't say that I see a great deal of difference, but on the weaker signals it does seem to hold a lock a bit better. Now, if August would just go ahead and get over, I could be playing with the A3 and see if things are better. I'm guessing right now, that my C Band issues are somewhat related to 8 foot dish and not being EXACTLY on on the alignment. I'm really close, but off just a smidge and at this point and time, I haven't gotten excited enough to troubleshoot it out. Maybe this fall when it is a bit cooler.

Thanks again.

edited to correct poor grammar/spelling.

 

[jjl]

am I right in thinking that the corotor would not work with an offset dish?

 

[Titanium]

am I right in thinking that the corotor would not work with an offset dish?

A Corotor should work fine with an appropriate scalar.

 

[jjl]

so that must be the reason i am struggling to find any sats(just been trying with one supplie3d), where could I buy an appropriate scalar?

 

[Titanium]

What offset dish and size are you using?

A conical scalar designed for offset FD like this one will make a world of difference!

http://titaniumsatellite.com/products#!/~/product/category=6743545&id=28257555

 

[Corrado]

Brian, is there a formula for the size of the scalar based on the size of the dish?

I was just thinking if the scalars I currently have on my 6' Prodelins were really engineered for 1.2m dishes. I have been using them for years with good results.

I remember a few years ago, I experimented with placing a metal nut or socket in the 9 or 3 o'clock positions in the scalar rings but I didn't get the same results in improvements other users were experiencing. Thinking back, this may be because my dishes are 1.8m not 1.2m. Not sure of the theory of what that object placed in the waveguide really was doing.

 

[Titanium]

A scalar is designed for the FD of the dish and not a specific size. A commercial dish manufacturer typically will provide a scalar that not only matches the FD, but also shapes the illumination pattern for the specific reflector dimensions.

W1GHZ has written some excellent articles on scalar and horn design. Check out http://www.qsl.net/n1bwt/chap6-4a.pdf and reference 6.4.3 - 6.4.25

 

[Magic Static]

A scalar is designed for the FD of the dish and not a specific size. A commercial dish manufacturer typically will provide a scalar that not only matches the FD, but also shapes the illumination pattern for the specific reflector dimensions.

W1GHZ has written some excellent articles on scalar and horn design. Check out www.qsi.net/n1bwt/chap6-4a.pdf and reference 6.4.3 - 6.4.25

I can't get to that link you provided

 

[KE4EST]

Try this link: http://www.w1ghz.org/antbook/conf/high_efficiency_prime_feeds.pdf

 

[Titanium]

http://www.qsl.net/n1bwt/chap6-4a.pdf

Strange how the forum chopped up that link! Here it is again. Maybe cut and paste?

 

[Magic Static]

http://www.qsl.net/n1bwt/chap6-4a.pdf

Strange how the forum chopped up that link! Here it is again. Maybe cut and paste?

Yes that worked Good info!