Convert CM120 KU LNB Mount to BSC421

[Spine]

Hello everyone,

Today I just built a small frame to hold a CM120 (channel master 120cm) fibreglass dish I got a while ago (not comitting to permanent concrete install just yet). The dish worked fine for Ku reception and I got some neat channels. Now I am attempting to try C band on this small dish.

I bought a BSC421 lnb and it came with a scalar ring that is supposed to be mounted to a prime focus dish (i am guessing) that has 4 or 3 arms from the dish. My CM120 has a small plastic ring (maybe 4-5cm diameter) that is supopsed to hold kU lnbs and I am just wondering what the best way to mount my C-band lnb to the dish is.

Thanks in advance for all the replies/suggestions!

 

[Anole]

About a year ago, a number of members did pretty much what you are describing.
There is at least one very long thread around here discussing all the relative merits , quirks, and solutions to that problem.

In the end, it looked like even the die-hards had to quietly abandon their 4' dishes.
On the other hand , 6' gets by pretty well.
I'm sure you want to experiment with what you have, and by all means do!

Note also, the use of conical scalers for the offset-feed dishes like you have.
I assume that bought a little better performance.
Of course, the off-axis reception of a 4' dish meant you might not be able to receive very well in the crowded parts of the Clarke belt.
In spite of that, some users got some C-band signals, and that's a whole lot more than nothing!

edit:
Just search on: bsc621 or maybe microbud
Here's one long thread: might be the one I was thinking about .
This forum has a wealth of good info just waiting to be mined.

 

[dem0nlord]

Best thing is to get C band feedclamp and arms for the CM. You can order these parts form Dow electronics, and they don't cost much. The hole in the clamp will be a bit larger than your C band LNBF, just make a bushing to go around it.

 

[caddata]

Here's my attempt at the DMS BSC621-2 mounted on a Channelmaster 1.2M.

The brackets are fabricated from flat .070" aluminum (free from the scrap pile) and the strut clamps are Non-Metallic Cable (Romex) Clamps from Lowe's (89 cents each). The feed is at the original Ku focalpoint. There's approx. 3" adjustment towards the dish and 4" away, plus it can be raised up, down, left, or right by sliding the appropriate strut in or out of the clamp. After the feed location is optimized, I may decide to cut the extra length from the struts.

When installing the brackets, the idea struck me that conical aluminum sheetmetal sleeves can be added to the flat scalar to duplicate the conical scalar that's so hard to come by.

Haven't had time to hook it to my receiver to see what happens, but I hope to sometime this week.

I'd be glad to supply a template of the brackets (they're all the same) as a PDF file that you can print , cut out, and trace around for anyone that would like to fabricate their own.

Harold

 

[Anole]

Beautiful job, CadData.
Keep up the good work.

You're going to drag me into this C-band stuff if I'm not careful.
Hope to see a 6' offset one of these days, and that'd just beg for a good LNBf mounting idea, like yours.

 

[gabshere]

very impressive Harold
you've done a top notch job ... i only hope i find the time to tinker with a small rig too. but first i got to set up & repair a couple in the 10 ft range.

the idea struck me that conical aluminum sheetmetal sleeves can be added to the flat scalar to duplicate the conical scalar

i seen somewhere here that someone used a funnel and coated it with alum foil , but are you thinking of just adding a flashing around the outermost scalar ring? would this suffice?
keep up the good work , as i always read with intrest, i might not understand sometimes lol but i like to read them

 

[caddata]

....just adding a flashing around the outermost scalar ring? would this suffice?....

gabshere:

With the dish and feed laidout in Autocad, I realized that I now have all the geometry available to profile each "sleeve" to fit over all the rings of a flat scalar. The "sleeves" will be straight on the side that attaches to the flat scalar, while the sides towards the dish will have an irregular curve as they intersect the focal cone. It should be more efficient than the "store bought" conical scalar because the "sleeves" are shaped to exactly fit my Channelmaster. The idea is similar to the shroud around the lense of some cameras. Those that have a stepped cone in front of the actual glass lense.

If you can imagine your eye being at the focalpoint, looking back towards the dish. The "sleeves" of the conical scalar would act as blinders do on a horse. The limit your eye could see would be only the outside perimeter of the dish. Not the area outside it. You could only see the dish no matter if you tried to look to the side. That would be 100% illumination. All the reflected and focused microwaves would be directed into the feed.

Harold

 

[PopcornNMore]

Very nice job! I plan to do the same with my Channel Master 1.2m and / or 1.8m dish.

 

[bloomdog]

.

I'd be glad to supply a template of the brackets (they're all the same) as a PDF file that you can print , cut out, and trace around for anyone that would like to fabricate their own.

Harold

I would like to build one. Please provide the pdf file. Thanks!!!!!!!!!

 

[Dishpointer]

I would like to build one. Please provide the pdf file. Thanks!!!!!!!!!

The files are located here courtesy of Harold: http://www.satelliteguys.us/c-band-satellite-discussion/101862-scaler-ring-removed.html

 

[pmb1010]

Harold,
what kind of results did you get from this?
Any attempt at C band digital (DCII) and/or DVB?

 

[bloomdog]

The files are located here courtesy of Harold: http://www.satelliteguys.us/c-band-satellite-discussion/101862-scaler-ring-removed.html

thanks

 

[caddata]

...results?....

PMB1010:

Haven't put it into service yet. I'm playing with the design of a hombrew polar mount with a linear actuator, but I'm having a hard time with keeping it simple and easy to fabricate. It'll be constructed using aluminum extrusions available at Lowe's or Home Depot. I plan to share it with the guys on the board when I'm finished.

Harold