CM 1.2m beats Fortec 1.8m on C band
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Friday night I verified that in order to receive strong KU band signals using the BSC621 LNBF on my 1.2m offset dish I needed to move the LNBF out further than the brackets allowed.
In order to once again receive KU band I disassembled the BSC621 LNBF and attached the original KU lNBF using the Channel Master junction bracket.
I tried mounting the BSC621 next to the KU LNBF using a hose clamp, but no signals were received. I really miss having a motorized C band dish. The results I have gotten using the 1.2m offset dish were fantastic using the brackets caddata designed.
I read a previous post this morning by Pete saying that KU band signals are received much stronger using the BSC621 if the feed cover is removed and replaced with thin clear plastic. I may give this a shot.
Another option would be to setup another CM 1.2m dish from the garage and have one motorized for C band and one motorized for KU band. This would be ideal, but the wife would throw a fit since I already have several dishes installed.
In order to once again receive KU band I disassembled the BSC621 LNBF and attached the original KU lNBF using the Channel Master junction bracket.
I tried mounting the BSC621 next to the KU LNBF using a hose clamp, but no signals were received. I really miss having a motorized C band dish. The results I have gotten using the 1.2m offset dish were fantastic using the brackets caddata designed.
I read a previous post this morning by Pete saying that KU band signals are received much stronger using the BSC621 if the feed cover is removed and replaced with thin clear plastic. I may give this a shot.
Another option would be to setup another CM 1.2m dish from the garage and have one motorized for C band and one motorized for KU band. This would be ideal, but the wife would throw a fit since I already have several dishes installed.
Being the engineer that I am, I once again removed the KU LNB and CM junction clamp from the 1.2m offset dish and reinstalled the BSC621 LNBF using the brackets Caddata designed. This time I received even better C band results, but KU was still the same. To receive the highest KU band signal the LNBF needed to be lower, but the center support pole was in the way.
To get the C band scalar ring dead center I first mounted it using the two side brackets and keeping the CM junction clamp in place. I then removed the CM junction clamp and attached the third bracket to the bottom. It seems that the third bracket needs to be longer in order to center the scalar ring exactly in the center. I will first need to make some modifications to the brackets. Until I do this, I removed the BSC621 once again and reinstalled the KU LNBF.
I am going to keep trying.
To get the C band scalar ring dead center I first mounted it using the two side brackets and keeping the CM junction clamp in place. I then removed the CM junction clamp and attached the third bracket to the bottom. It seems that the third bracket needs to be longer in order to center the scalar ring exactly in the center. I will first need to make some modifications to the brackets. Until I do this, I removed the BSC621 once again and reinstalled the KU LNBF.
I am going to keep trying.
Pop:
Loosen all the strut clamps. Pull feefhorn down while still pointing towards center of dish. The lower strut will bow enough to allow lots of downward adjustment. I didn't want to bend the bottom strut because of possible future return to stock. Retighten all the clamps. Same procedure I use for tweaking.
Did you get the drawing that shows dimensions for locating the mouth of the feedhorn top to bottom and left to right? If not, I can post them again. The dimensions were posted with the bracket drawings originally.
Harold
Thank you for the tip Caddata. Yes, I have this document somewhere and will adjust feed again.
With this C/KU LNB setup using your CM 1.2m dish do you receive KU from AMC 3, Galaxy 25 and Galaxy10R as good as using a standalone KU LNBF? This is why I keep switching, because the KU doesn't come in as good and I lose my favorite KU band channels like RTN, PBS and others.
With this C/KU LNB setup using your CM 1.2m dish do you receive KU from AMC 3, Galaxy 25 and Galaxy10R as good as using a standalone KU LNBF? This is why I keep switching, because the KU doesn't come in as good and I lose my favorite KU band channels like RTN, PBS and others.
Sorry to jump back to this earlier topic, but do you guys believe a conical scaler ring for my BSC621 on my 6' prime focus will help with interference from adjacent satellite signals? Most of my C-Band is good but right around 89W, 91W, and most of 93W, depending on other feeds going on at the time, my reception is terrible on those birds. I was told that it's because of the interference and I believe that to be correct. Will the conical scaler ring help with prime focus ya think?
Can't really compare my setup to anything else because I've only used the dual band LNBF on it. Didn't record the levels when I was using the .9M Fortec and a Ku LNBF, but I think it's about equal. I do, however, get all the 10r Ku transponders I was getting with the old .9M with 75% to 100% levels on the 1.2M. C band transponders are 40% to 60% on 10r. The dish isn't motorized, just fixed on 10r.
Harold
Well, I just removed the KU LNBF and reinstalled the BSC621 once again using the brackets Caddata designed. I bet the neighbors think i'm nuts. I must have installed and reinstalled this LNBF 5 times today.
Now, I have gotten the highest KU levels I have had with this LNBF to date. The C band also comes in very good. I am going to leave things go for the next few days and log signal levels before tweaking.
Thank you everyone for all your help as always. I will keep you posted.
I must have installed and reinstalled this LNBF 5 times today. Now, I have gotten the highest KU levels I have had with this LNBF to date. The C band also comes in very good. I am going to leave things go for the next few days and log signal levels before tweaking.
Thank you everyone for all your help as always. I will keep you posted.
Pop:
How close are you to the dimensions that locate the feedhorn that I came up with? They should be close to optimum. I laid the dish out in Autocad and located the BSC621 so as to illuminate the reflector to within 5/8" of the perimeter. There's plenty of adjustment in the brackets to fully illuminate the reflector if you like. It may even work better to over illuminate it by a fraction.
I was looking down the throat of the BSC621 the other day and noticed the Ku scaler in the back. The Ku portion will come apart at the flange if you break the seal. I wonder what would happen if one fabricated another scaler (sheetmetal) with a longer center tube and moved it further towards the C Band probes inside? Like near the dowel that passes through the center. I might try that later.
Harold
conical scalers
Live rates at 2007.10.08 06:17:14 UTC
5,880.00 JPY.....=....... 50.2050 USD
Japan Yen ...........United States Dollars
1 JPY = 0.00853826 USD
1 USD = 117.120 JPY
I really wasn't joking around when I said I found $3.50 C-band LNBs in China!
(large quantity, and so wholesale price, to be sure)
So, show me a C-band conical scaler for . . . $5 retail, please!!!
okay, make it $12.50, but with shipping! -
ALSO, if you'll check back a year or so when the BSC421/621 first hit the market ,
there were all these posts about making a conical scaler!
One guy who was a machinist did and got 'em tested by some members.
Use the search feature and dredge up that info... it's gold!
According to Xe.Com, that's another $50 solution!
Live rates at 2007.10.08 06:17:14 UTC
5,880.00 JPY.....=....... 50.2050 USD
Japan Yen ...........United States Dollars
1 JPY = 0.00853826 USD
1 USD = 117.120 JPY
I really wasn't joking around when I said I found $3.50 C-band LNBs in China!
(large quantity, and so wholesale price, to be sure)
So, show me a C-band conical scaler for . . . $5 retail, please!!!
okay, make it $12.50, but with shipping! -
ALSO, if you'll check back a year or so when the BSC421/621 first hit the market ,
there were all these posts about making a conical scaler!
One guy who was a machinist did and got 'em tested by some members.
Use the search feature and dredge up that info... it's gold!
Offset Dish C Band Scalar Ring
Stay tuned, I might just have a $1 solution by tonight. If it works, I will be providing full details, photos and parts list.
Stay tuned, I might just have a $1 solution by tonight.
If it works, I will be providing full details, photos and parts list.
Stay tuned, I might just have a $1 solution by tonight.
Yay!!!, I hope it works
I just finished my $1 scalar ring, but don't have time to try it out due to the time.
However, I discovered tonight that the more I tweak the KU band the better C band is received and less if any interference from adjacent satellites is seen.
This leads me to believe that a larger dish (10' or larger) is mainly necessary for dishes that are more poorly aligned. If you only have C band on your system you would never tweak the signal enough, because you would never need to due to the size of your dish. It is almost like having a computer with a very large CPU and memory. For those that have a computer with a smaller CPU and less memory they need to be more careful as to what applications they run and often tweak their computers by running defrag and saving space on their hard drive to enable the applications to run faster.
I now have more KU and C band channels than ever before after making finer adjustments tonight. I am still amazed that this is only a 4' dish. I will be posting some screenshots and signal strength readings shortly so others can compare against their systems.
However, I discovered tonight that the more I tweak the KU band the better C band is received and less if any interference from adjacent satellites is seen.
This leads me to believe that a larger dish (10' or larger) is mainly necessary for dishes that are more poorly aligned. If you only have C band on your system you would never tweak the signal enough, because you would never need to due to the size of your dish. It is almost like having a computer with a very large CPU and memory. For those that have a computer with a smaller CPU and less memory they need to be more careful as to what applications they run and often tweak their computers by running defrag and saving space on their hard drive to enable the applications to run faster.
I now have more KU and C band channels than ever before after making finer adjustments tonight. I am still amazed that this is only a 4' dish. I will be posting some screenshots and signal strength readings shortly so others can compare against their systems.
Keep in mind the angle of the cone should match the angle of the dish for optimum performance. The side and top views of the dish shown on the drawings of the feedhorn brackets show that angle. The lines from the edge of the dish to the focal point create the angle required.
Think of the feedhorn as a camera. Looking towards the dish, it should only see the perimeter of the dish as a maximum. Anything less than the perimeter effectively reduces the size of the dish to something less than 1.2M. Suddenly the 1.2M dish is a 1M dish. Anything more than the perimeter allows background radiation from the earth into the feedhorn reducing signal strength.
The steps inside the "store bought" cones are carefully designed to reject spurious signals from outside the dish (adjacent satellites).
Harold
I fully agree Caddata that a "store bought" cone would be ideal. However, I love to experiement and come up with new ideas which is why I love FTA satellite. If I can get a $1 homemade cone work 1/2 as good as a $50 store bought I am happy.
This past weekend, I was getting frustrated adjusting the C/KU LNBF on the 1.2m dish for the best possible KU band reception. My wife than said to me "But isn't that most of the fun and why you enjoy this hobby so much? If you were able to just buy a magical part that gave you 100% perfect C/KU band reception you wouldn't be happy". She was exactly right and knows me very well.
This past weekend, I was getting frustrated adjusting the C/KU LNBF on the 1.2m dish for the best possible KU band reception. My wife than said to me "But isn't that most of the fun and why you enjoy this hobby so much? If you were able to just buy a magical part that gave you 100% perfect C/KU band reception you wouldn't be happy". She was exactly right and knows me very well.
Sounds like a good "girl" you got there, keep her around.
The point I didn't explain very well is the geometry of the cone .
During the layout of the dish and feed the notion occured to me that sleeves could be added to the flat scalar that would duplicate the cone.
Imagine sheetmetal sleeves that slip over each of the flat scalar rings. Laid out flat, each sleeve would have an irregular curve on one side and flat on the other and have a length equal to the circumference of each ring on the flat scalar. The sleeves would then slip over each ring on the flat scalar. Each sleeve would be slightly different in profile. The edges of the sleeves would intersect that cone of signals reflecting off the dish, directing it into the throat of the feedhorn. It's hard to describe but simple in geometry.
Does this make any sense?
Harold
I'm pretty good at visualizing, but it took me two reads to even -think- I understand your idea.
But it might be the easiest solution...
Can you scan a hand-drawn sketch?
Maybe photograph it from a white-board?
No need for the details of a cad-drawing.
edit:
Okay, after three reads, I got it.
And the "irregular" curve on the one side of each would be needed to match the shape of the dish?
You think that'll work?
Isn't the offset dish a circle from the viewpoint of the LNB, so wouldn't that make the scaler rings ... what's the word...?
So, wouldn't the cone shape of the scaler be symmetrical...no, -identical- all the way around the circle???
Geez! Now I'm gonna have to draw a picture!
-cylindrical-
But it might be the easiest solution...
Can you scan a hand-drawn sketch?
Maybe photograph it from a white-board?
No need for the details of a cad-drawing.
edit:
Okay, after three reads, I got it.
And the "irregular" curve on the one side of each would be needed to match the shape of the dish?
You think that'll work?
Isn't the offset dish a circle from the viewpoint of the LNB, so wouldn't that make the scaler rings ... what's the word...?
So, wouldn't the cone shape of the scaler be symmetrical...no, -identical- all the way around the circle???
Geez! Now I'm gonna have to draw a picture!
-cylindrical-
I like your idea Caddata and fully understand what you are trying to say. If my $1 solution does not work well, I might just try your idea.
That's what I thought until I laid the geometry out and found the stock feedhorn wasn't looking at the geometric center of the offset dish. The satellite sees the elliptical dish as almost a perfect circle (because of the 22 degree+ or -), but the feedhorn (not looking directly at the center of the offset dish) sees it as an ellipse. I've seen some offset dish feedhorns that weren't symetrical in the manner you speak and wondered why.
Some of the geometry is starting to make sense to me. But the stock Channelmaster Ku feedhorn was conical as you described but smooth on the inside and not stepped like some, which confuses me a little.
This probably needs lots more investigation and experimenting. Popcorn is the leader in experimenting so far and I'm enjoying his posts.
Harold
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