Primestar Elliptical Scalar Ring C Band

[Satcom1]

My project has to capture as many C Band channels as I can on a small dish. The Primestar 1m X .7m was chosen because of it's common availability in USA. It was manufactured by Channel Master and is still in production through Andrew Corporation but only as a commercial grade antenna.

The dish was used for the Primestar DSS service and had a KU LNBF with an elliptical Scalar ring. In another project I took a Standard LNBF voltage controlled for V/H and cut off the conical Scalar ring and fixed the LNBF to the P*E Scalar with Crazy Glue. It was an improvement in that the new LNBF is rated at .3 N/F , added voltage controlled switching and provides more conversion gain. This dish when used with any conical Scalar performs like a .7m offset dish. With the Elliptical Scalar it works better than a .9m dish.

So onto C Band. The dish is not illuminated properly by using a flat Scalar ring and with a conical Scalar performs like a .7m dish.

Walrus 1957 developed a high performance Conical Scalar cone set to maxumize performance of a 1m offset dish. In testing it outperforms the consumer manufactured conical rings.

I made up a paper set of his stacked cone Scalar rings and then marked off the geometry scaled up from the P*E KU Scalar. These were then rolled flat and used as template for sheet aluminum parts. I also made a sleeve that slips over the 65mm C Band LNBF throat. The cones are assembled to this slip sleeve so that it can be reused on other LNBF.

The cones are spaced 15mm apart, just as in his conical set. Performance of the dish is improved by a significant amount. The dish is motorized with a Stab H-H motor and tracks the arc with USALS.

Conclusion:

If a small size dish is desired or required this stacked set of cones will provide the maximum gain and cost very little <$5USD.

For most folks the conical Scalar ring (Second Picture) made for WS International kit # WS-KU2C KIT is easy and very cost effective to implement on a 1 meter offset dish for C Band Mini-BUD systems.

 

[Satcom1]

Here are just a few of the channels captured, some are HD and my Coolsat 6000 is not.

 

[Satcom1]

Here are pictures of the P*E Feedhorn attached to a current production high performance LNBF. The LNBF was modified with a hacksaw to remove the conical Scalar feedhorn.

 

[wilfredomix]

Thanks :-worship

 

[Satcom1]

Here are Pics. of paper templates laid flat from cones trimmed to elliptical shape.

Measure to outer horizontal edge from inner edge:

Inner cone 1/2"

Middle cone 1 1/2"

Outter cone 2 1/2"

 

[Satcom1]

Here are some more of the C Band I enjoy on this little dish:

G16C- 3845 H 15030 THIS, CW, ABC, NBC, FOX, ABC HD, Occ. Use. When these channels are peaked others are lost.

PAS 9C NHK English

Galaxy 23 Sports Time Ohio, Sportsmans Channel.

Galaxy 3C Horse Racing

Wow- no rain fade.

 

[searay]

Satcom1,
I wish I had found this thread a couple of weeks ago. I have used a 40" Primestar dish driven by a Stab HH120 motor connected to a Pansat 3500SD receiver for a couple of years. I live on the Eastern shore of the Chesapeake Bay in the US.
I have only used this setup for Ku band but would like to also get a few C band channels. My Ku reception is very good across the entire belt so I know the mount is pretty much perfect.

I purchased an extra arm for the dish so I would be able to switch setups by renoving only the one attaching bolt and the cables. I carefully measured the distance and angles of the the arm with a original Primestar LNB mounted on it. I made an adapter out of aluminum to mount a WS International DMX741 Ku and C Band LNB. The centerline, angle, and throat opening of tne new LNB mounted on the new arm are pretty exact compared to those of the original Primestar LNB. My problem is that the signal strength provided by the new LNB (on its Ku band) are about half of what I had on my old Ku LNB.

I tried tweaking my dish Lat and Long physical adjustments with no improvement. The new LNB can be used with a single coax and switched internally, or, the user can use two cables and avoid any swithch problems. I'm using seperate cables. I set the skew adjustment of the LNB at 12 O'clock as specified in the user instructions. Rotating the LNB or sliding it closer toward or away from the dish does not seem to have any effect. I had also purchased the conical scalar ring and out of desperation (even though it is only effective on the C Band signal) tried installing it also. No help.

I noticed in your photos that you are not using the arm originally supplied with the Primestar dish. Would you be gracious enough to give me the dimensions and necessary measurements to reproduce your setup? It would be greatly appreciated.

Thanks in advance,

searay

 

[Satcom1]

Hi Searay,

Unfortunatly these LNBF do not work Dual Band on a small Offset Dish. Maximo who posts on Satilliteguys.us claims that by adding a 1/2" extension (metal or plastic with foil) between the C and Ku sections that the DMX741 will work for Ku. No one todate has confirmed this.

The arm is not important. but if you want details please search satelliteguys.us for Satcom1 posts.

Dreamfox of that site had the best solution to the C/Ku Linear/Circular adaption to a small dish.

Walrus1957 of that site now claims that using a flat Scalar ring with a wrench socket placed at the 3 O'clock position of the inner most ring produces strong improvements on smaller offset dishes. This has been confirmed by one other.

My elliptical scalar ring may be improved by rotating it 90 degrees and adding another outer cone of progressive measurement.

Best of Luck

Satcom1

 

[searay]

Satcom 1,

I can't thank you enough for taking the time to respond with such thoroughness and real help. I thought I had at least a little idea about what was going on. After reading through the threads you supplied I realize I don't know squat. I have a lot more reading and testing to go through. What a great hobby! I am retired and don't have a lot of money to spend on TV even though it's pretty much my main source of entertainment so FTA is really important to me. Thanks again.
searay

 

[Satcom1]

Hello Searay-

It is a consuming hobby. Mostly of time and effort. Without anything but intention, one can go out and hunt up all sorts of free dishes. Often times; Actuators, receivers, corotors and assorted LNBF are free. The find is a good feeling, knowing you saved it from the scrap bin.
I enjoy the contributions that other members post and all the help you need to get started. For me it is a full time job.
I get better quality and more HD FTA then I could OTA.

When someone posts that they have found a 30% SQ increase by adding a socket wrench to their Scalar, I'm inspired by what we don't know and the Edison in us all.

 

[doktorofsat]

As I know all the amrican channels are H/V polarization . isn't it?

 

[Satcom1]

All FTA channels are Linear,almost. Most all feeds are linear. All Subscription channels are Circular, DSS,DVB-S,DVBs2,FSS,Turbo8, etc.
The NASA and ION channels are ITC In The Clear but Circular.

 

[searay]

Satcom1,
I hate to bother you again, but I have not found the information I need in spite of many days of searching and reading. In addition to my Primestar dish, I want to add another (surprise!!) larger dish. Hopefully something large enough to allow me to subscribe to a few channels like SyFy and the Military Channel. I would like to keep the dish size to a minimum. I think I have gotten enough info to determine that an 8.5' dish is necessary to scan the C band satellites. BUT ... is this a mesh dish needed to get 99% of the available programming or would a 6' solid dish do as well? I'm completely confused by the different terminologies used to describe the "sensitivity" of the dishes and LNB's. It's like going to a supermarket and trying to get the best "bang for your buck" when the labels refer to different serving sizes, serving units, metric, english, etc. I have tried to find websites that show maps of the USA showing the minimum dish size required to reliably receive the signal of each satellite. I can't seem to find anything newer than a year or two old which is not very useful given the constant state of flux the satellites and programming is in. I'm not asking you to give me all the answers, but maybe an idea of where to look to get the "real skinny". I apologize again. If there is a forum that is current and has people like myself who can't afford to subscribe to DTV or DN and really don't need or want all the channels in the expensive packages, please steer me to that site, I'll be happy to get involved.
searay

 

[Satcom1]

Hi Searay,

Because of your location a larger dish is required for good C band reception. In Omaha one can get good C band on a 1.2m offset dish.
A solid dish is a better performer then a mesh dish. The older mesh dishes (prior to 1991) are good for C but not Ku. However, most get the bigest dish they can find and use it for C band, then get a 1m or 1.2 m offset for Ku.

Any of the cheap 13K C band lnbf work very good. Panorama, BSC 421, DMX241. My first lnbf for Ku was an Invacom qph-031 and I soon replaced it for a cheapo eBay Standard 10750 lnbf.

Sadoun has a good price on a 6' PF polar mount dish.

I'll PM you with info on another site you can use for more info.

edit: you don't have PM privelages, sorry. Google satelliteguys.us

 

[whitworker]

Hello,

Thank you for posting your elliptical scalar ring.

I've been trying to figure it out. This one will be made, and I will post results.

 

[searay]

Have you gotten any result from this yet?

thanks,

searay

Hello,

Thank you for posting your elliptical scalar ring.

I've been trying to figure it out. This one will be made, and I will post results.

 

[Satcom1]

Searay-

Have you added the 1/2" spacer to your c/ku lnbf?