Fine tuning the C-Band LNB Best Practices? (1 Viewer)

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Vondertrenk

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Aug 30, 2007
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Hi Guys, How to know when the LNB has reached its optimum point, before tihgting up scres & bolts?

WIth the snow already melt and temperature continuing to rise in SW Ontario, it won't be too long before playing again with my 6' BUD.
Is there any best practices to tune the C-Band LNB up? Ku dish LNB tuning is relatively easy procedure done from beneath w/o interfering with the satellite path (for offset dishes) however with C-Band dish is another story; fine C-Band LNB tuning implies to physically rotate the LNB a few segments of arc at a time and check your signal before tightening the bolts up> I follow the same aproach for focus tuning. To do that you will position in front of the dish afecting the incoming signal. That creates noise on the receiver to a point that you may need to restart it again.
This procedure is what I follow, however I find it sort of cumbersome and lenghty.

Is there any tool of any other way to rotate the LNB without standing in front of it and w/o affecting the incoming signal? Please do share your experiences.
 

. Raine

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Aug 6, 2013
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I do it standing on a step ladder in front of it with my FS1 meter. Surprisingly, the ladder and me standing in front of it doesn't seem to interfere with the signal much. Would be nice to have a better way though, last summer I took a header off the ladder and broke two Norsat LNBs. :(

I just got done tuning my C band dish up last weekend and now I have 87 W back again, the Luken mux had been MIA for me for most of the winter.
 

FaT Air

HOA Free Zone
Feb 27, 2010
6,668
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97W 48N
With the LNBF's that I've used, I've found the manufacturers skew mark to be 'right on'.
What's worked for me, being the maximum "Q" is quite 'broad' using the S9, is to adjust the skew/focal length to a lower = reading in each direction of maximum "Q", then set it to midway between. (I also tweak the elevation/azimuth with this procedure)
If possible, run the dish to far east or west satellite, so you're not 'hovering' over the dish when doing this.
With the 10 ft, there's only a slight 'body' effect when in front of it, so it's of little concern. But on a 6 ft, you may want/have to go up and down the ladder a few times. Don't know of any 'tool' .
Before 'going after' skew and focal length, ensure that the feed is centered and aimed 'dead center' of the dish.
 

77TA

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Aug 27, 2013
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Arkansas
I start out using the attached procedures to rough in the lnbf in the scalar. If your dish is motorized set it at your true south satellite with the skew set to zero and scalar aligned with the numbered ring that matches your f/D ratio. If it is stationary set it the same way but then skew the lnb to match the correct skew for your location(skew settings can be found using this http://www.satstar.net/setup.html?config=bfcs .

Tighten down the lnb then test the settings on a couple of sats to get quality readings. You will probably be close enough to get most of the stuff you want. From there I adjust the skew first by moving it one direction about 10 degrees and checking to see if it improved the reading I previously had. If it improved I go a little further the same direction, if not I go 10 degrees the other way and try it. Once the skew is set I move to the in/ out position and do it similarly.

I tighten the lnbf down using a cordless drill each time and move away from the dish. It really doesn’t seem like a big deal to me because once its roughed in it’s not going to need any big adjustments. And at my height I don’t have to use a latter to adjust the lnbf on my 6 footer. InstallGuide_CBand2_Page_1.jpg InstallGuide_CBand2_Page_2.jpg InstallGuide_CBand2_Page_3.jpg InstallGuide_CBand2_Page_4.jpg
 

KE4EST

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I do the same as most on a step ladder in front of dish, I don't seem to cause much difference to my 10 footer.
 
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Vondertrenk

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Aug 30, 2007
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Thanks guys, excellent tips.

I know a stepladder may not affect that much a 10 ft dish but mine is the junior 6' Fortec. I know there are multiple factors to consider when doing the tuning, for example the same satellite may have different pinpoints for diffferent channels and you may need to move the dish one or two deg West or East for eah one, you may also need to adjust skew on a different arc again, depending on the channel. That is specifically true with circular polarization. (here is where Titanium ASC1 becomes a great tool, free advertisement :eek:)

What I am trying to avoid is having myself or a big object in front of the dish while doing the fine tuning; at this point, I may have found a decent signal for a specific channel, I am just doing final tweaking and need to have a clear path to the satellite. At least for the small 6 ft dish, the aditional microvolts may be the difference.
 

FaT Air

HOA Free Zone
Feb 27, 2010
6,668
913
97W 48N
Circular polarization doesn't, and shouldn't, require 're-skewing'. The 'great advantage' so to say, so those weekend warrior D15H and Diwreked installers have 'less to adjust' so as to not become 'overwhelmed'.
same satellite may have different pinpoints for diffferent channels and you may need to move the dish one or two deg West or East
I'd be investigating feed centering and aim (at the center of the dish) But another factor I think could be the 'root' cause and that's adjacent interference as a 6 ft's beamwidth is far greater than the satellite spacing of 2°. There is only 1 'prime' focal point.
you may also need to adjust skew on a different arc again
There is only 1 arc. But here again I think it's the beamwidth of the dish. Adjusting skew to minimize adjacent interference. I.E. a 3db decrease in interference signal results in -3db of desired signal, but still enough for 'lock'.
 

richyrich

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Sep 2, 2008
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I like to say, it is realization of "a science" that must be very "fine". Theoretically, science is the experiment. The success is in experimentation; where you realize a "full potential"; and use every bit of the effectiveness that the experiment gives you as the result that you experimented. If you already :cool:knew "the science"; you would not have to experiment yourself as to what really works! You would already know.​
 

Vondertrenk

Thread Starter
SatelliteGuys Pro
Aug 30, 2007
285
36
Canada
Talking specifically about 40 W SES6, some channels are available at a specific skew point but rotating the LNB a few degrees (or segment of arc) I may miss some and get some new channels. For example, at the moment the LNB is in a position that allow me to receive Isla TV but at the same time I am missing RT (No that I like that channel at all, just for the DX hunting pleasure :)) and some stations from Argentina. However if I change the skew to the point where I receive RT and the argentinian channels ( 3778 L & 3803 L), I will be missing the Isla TV and some others (3658 L).

Circular polarization doesn't, and shouldn't, require 're-skewing'. The 'great advantage' so to say, so those weekend warrior D15H and Diwreked installers have 'less to adjust' so as to not become 'overwhelmed'.




I'd be investigating feed centering and aim (at the center of the dish) But another factor I think could be the 'root' cause and that's adjacent interference as a 6 ft's beamwidth is far greater than the satellite spacing of 2°. There is only 1 'prime' focal point. There is only 1 arc. But here again I think it's the beamwidth of the dish. Adjusting skew to minimize adjacent interference. I.E. a 3db decrease in interference signal results in -3db of desired signal, but still enough for 'lock'.

Guys, investigating analyzing etc. is the right first step, however things always work on the paper, on the desing table (well, that was before computers became cheap, I gues today we shall say "everything works well on the tablet") but when coming to the real world, specially with radio propagation, there are many variables that can influence the final result; regardless of how precise are your calculations, quite often you may need the final tuning; this is why is so important to be able to perform the final adjustment in the appropiate environment.

That is why my initial question has been always:

Is there any long arm tool or whatever that would allow me to adjust the position of the LNB without standing in front of the dish?
 

FaT Air

HOA Free Zone
Feb 27, 2010
6,668
913
97W 48N
Think you'd have to fashion something up as I've never seen, or heard of, such a tool. Problem I can see arising is keeping the feed horn 'straight' and the focal length 'steady'.
Maybe, somehow, incorporate a TV rotor like the early BUD's employed to rotate the LNBF for polarity control(?). An alternative could be a stepper motor.
All in all, after thinking about it a bit, they way to go is probably a polarotor feed horn w/LNB and something* to run it.
*Alternatives : Titanium ASC-1, analog receiver, Budfoot Files, (satguys thread), or a Simple 'Servo Driver' It's just a 1 to 2ms pulse to move the servo.
The ASC-1 also is the actuator controller in addition to servo control.
 

richyrich

SatelliteGuys Pro
Sep 2, 2008
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Circular polarization doesn't, and shouldn't, require 're-skewing'. The 'great advantage' so to say, so those weekend warrior D15H and Diwreked installers have 'less to adjust' so as to not become 'overwhelmed'.
I'd be investigating feed centering and aim (at the center of the dish) But another factor I think could be the 'root' cause and that's adjacent interference as a 6 ft's beamwidth is far greater than the satellite spacing of 2°. There is only 1 'prime' focal point. There is only 1 arc. But here again I think it's the beamwidth of the dish. Adjusting skew to minimize adjacent interference. I.E. a 3db decrease in interference signal results in -3db of desired signal, but still enough for 'lock'.

I do also agree, as to adjacents; but if the ability of the aim and skew of the dish is totaled by 3 dimensional space, then if you aim all three for 1 satellite, it still provides quality and a picture from "each 3 degree's in space"; and the FS1 shows that even at 3 degree sidelobes a six foot dish can be "put to enough gain" the proper aiming (but you have to move the dish to one exact aim). The meter's responsiveness with a short cable comes to mind as to its realization that you need 32 satellite dishes to do them all "prefectly as a pic"; instead of using a motor (like the cable company does). A beautiful flat perfect dish starts it; and the lnb braces it in, and it DOES NOT NOT NOT MOVES FROM THERE, except when the dish lnbf concept move a millimeter off of each set!

What i must ask is the meter and the dish and the little short cable to use at the dish! Why all your posts are correct, thanks to the quoters and the commentary!
 

T4Runner

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Pub Member / Supporter
Apr 3, 2010
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I do also agree, as to adjacents; but if the ability of the aim and skew of the dish is totaled by 3 dimensional space, then if you aim all three for 1 satellite, it still provides quality and a picture from "each 3 degree's in space"; and the FS1 shows that even at 3 degree sidelobes a six foot dish can be "put to enough gain" the proper aiming (but you have to move the dish to one exact aim). The meter's responsiveness with a short cable comes to mind as to its realization that you need 32 satellite dishes to do them all "prefectly as a pic"; instead of using a motor (like the cable company does). A beautiful flat perfect dish starts it; and the lnb braces it in, and it DOES NOT NOT NOT MOVES FROM THERE, except when the dish lnbf concept move a millimeter off of each set!

What i must ask is the meter and the dish and the little short cable to use at the dish! Why all your posts are correct, thanks to the quoters and the commentary!

Just a question.... Do you drink?



Posted Via The FREE SatelliteGuys Reader App!
 

richyrich

SatelliteGuys Pro
Sep 2, 2008
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Just a question.... Do you drink?



Posted Via The FREE SatelliteGuys Reader App!

I used to quite frequency them in, and it always works. But I was stuttering at the same time, so the Law of averages and Time caught up with me, and now I still drive! via science!:popcorn

It was the pain I was removing by drinking in the end that I decided my memories are more important than the pain! Thanks. But your forumn is for satellite tv and how the meters tell you S/N and the signals realized level per tp; -10 to -5 the final gain of the aim; and why the installation and equipment work together so perfectly i have met 10's of thousands of them professionally...

The problems of 3 degree sidelobes can be scanned into using the receiver however (because of adjacents), and if you move off the adjacent 2 degree spaced signals by programming a new satellite name and ; say 1 degree defined over away from that adjacent, then the quality of the TP you want gets better, because you moved away from the adjacent satellite that has the frequency you are tuning from that new position in space! Installers do this also by moving the lnbf for skew; but actually they are aiming the lnbf to about 1-4 degree of "looseness" that actually makes satellite receiver circuits work! It is only a mistake, but works if the other adjacent is not used (in the direction moved to)2

Broadcasters could actually checkerboard the satellite signals and achieve 3 degree sidelode "prefectionaries" (like sugar)! Look at how small ku is now, with a like 15 degree dish; because the power of ku satellites in space are 3 times stronger each step in technology; and spacing of their sats too!
 
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Vallenato

SatelliteGuys Pro
May 25, 2011
221
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America
Talking specifically about 40 W SES6, some channels are available at a specific skew point but rotating the LNB a few degrees (or segment of arc) I may miss some and get some new channels. For example, at the moment the LNB is in a position that allow me to receive Isla TV but at the same time I am missing RT (No that I like that channel at all, just for the DX hunting pleasure :)) and some stations from Argentina. However if I change the skew to the point where I receive RT and the argentinian channels ( 3778 L & 3803 L), I will be missing the Isla TV and some others (3658 L).
Guys, investigating analyzing etc. is the right first step, however things always work on the paper, on the desing table (well, that was before computers became cheap, I gues today we shall say "everything works well on the tablet") but when coming to the real world, specially with radio propagation, there are many variables that can influence the final result; regardless of how precise are your calculations, quite often you may need the final tuning; this is why is so important to be able to perform the final adjustment in the appropiate environment.
That is why my initial question has been always:
Is there any long arm tool or whatever that would allow me to adjust the position of the LNB without standing in front of the dish?
This is happening to me on 40.5W but adjusting little bit the Focal Point (Push in/out). Since 3 years ago when I have installed My 6ft sadoun directly to 40.5 w I have had a lot knowledges with this satellite:rolleyes:
I have tested skew (rotation) movements on this satellite and I did not see significants changes.
I have tested some Dielectric arrow & "T" plate but not full improvements so far (the same thing improve some channels and lost others) probably I need to do more until I found the FORMULA. I have on mind "Despolarizador Turbinado" but Really I need a time and test, test and test..So far my best solution is just that the front plastic cap of the LNB is removed this has improve more quality in some channels but the problem that I am seeing is when is raining, My signal is drop.:(.I know that I have some Missings channels on this satellite but At least 75 Clear Channels are not bad to Atlantic Satellite .;).
I dont know .. Could be The Circular polarization? My Installation that is on the ground and not over the roof, The 6 ft on size (probably if I test this satellite on my 8 ft this will not happen):confused: I dont know
but I am agree with you:
"there are many variables that can influence the final result"
I forgot: I am adjusting my LNB with my hands extending my arm and stand over the ground
 

Vondertrenk

Thread Starter
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Aug 30, 2007
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Canada
I do the tweaking like you Vallenato; By extending my arm and hide my body as much as I can from the dish surface, however my arms are not long enough to hide all my body!!! :eek::):D
 

Titanium

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May 23, 2013
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I had made 6 foot pole with a cradle and rubber strap. Lightly loosen the feedhorn screw(s) and be able to stand clear of the reflector. Didn't use it much except on fixed dishes without polarity servo.

Your challenges are mainly due to the undersized dish and using a LNBF. With a larger 2 degree compliant dish, there is little feedhorn adjustment required after centering the feedhorn, setting FD and skew. Adjacent satellite interference from side lobes is adequately attenuated and the polarity skew offset can be optimized the the servo for each satellite and polarity.

Otherwise, you are on the right track. Make yourself skinny and step away to verify signal gains or losses. The older I get, I do find it harder to make myself skinny in the side profile.... :D


Brian Gohl
Titanium Satellite
 

Vondertrenk

Thread Starter
SatelliteGuys Pro
Aug 30, 2007
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Canada
Thanks FaT Air, this is what I have been asking for. My comments are:

Polarotor will fix the issue with the Skew when connected with an ASC1. Only problem is that the noise figure for the Polarotors LNB is higher than dual-polarity units; ex 20 dB for the Chaparral C-Band LNB. That can be an issue for small dishes like my 6 ft.( am I correct?)

Polarotor will not fix the issue for the focal distance, still need to be tweaked manually.

West/East deviation can be fixed always creating another satellite on the receiver list and positioner controller. I do that for example with 97W and 98 W.

I like the idea of the polarrotor anyway, but still will need the long arm tool to fine tuning. At the moment I am very happy with the new C1 PLL, lots of improvements over the old 621 but the idea of adjusting the skew all the times is very interesting.

Another idea would be to buy a bigger dish but the costs for polar mount C-Band dishes bigger than 6 ft are nothing but showstoppers, if you find one in Northamerica.



Think you'd have to fashion something up as I've never seen, or heard of, such a tool. Problem I can see arising is keeping the feed horn 'straight' and the focal length 'steady'.
Maybe, somehow, incorporate a TV rotor like the early BUD's employed to rotate the LNBF for polarity control(?). An alternative could be a stepper motor.
All in all, after thinking about it a bit, they way to go is probably a polarotor feed horn w/LNB and something* to run it.
*Alternatives : Titanium ASC-1, analog receiver, Budfoot Files, (satguys thread), or a Simple 'Servo Driver' It's just a 1 to 2ms pulse to move the servo.
The ASC-1 also is the actuator controller in addition to servo control.
 

Vondertrenk

Thread Starter
SatelliteGuys Pro
Aug 30, 2007
285
36
Canada
Jab wohl!
I have spent quite a lot of resources and time trying to stay on decent weight but time is running and is more and more difficult every day. I could ask my son but even the new generation are not as skin as we used to be:D

I had made 6 foot pole with a cradle and rubber strap. Lightly loosen the feedhorn screw(s) and be able to stand clear of the reflector. Didn't use it much except on fixed dishes without polarity servo.

Your challenges are mainly due to the undersized dish and using a LNBF. With a larger 2 degree compliant dish, there is little feedhorn adjustment required after centering the feedhorn, setting FD and skew. Adjacent satellite interference from side lobes is adequately attenuated and the polarity skew offset can be optimized the the servo for each satellite and polarity.

Otherwise, you are on the right track. Make yourself skinny and step away to verify signal gains or losses. The older I get, I do find it harder to make myself skinny in the side profile.... :D


Brian Gohl
Titanium Satellite
 

waylew

SatelliteGuys Pro
Aug 23, 2010
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I had made 6 foot pole with a cradle and rubber strap. Lightly loosen the feedhorn screw(s) and be able to stand clear of the reflector. Didn't use it much except on fixed dishes without polarity servo.

Your challenges are mainly due to the undersized dish and using a LNBF. With a larger 2 degree compliant dish, there is little feedhorn adjustment required after centering the feedhorn, setting FD and skew. Adjacent satellite interference from side lobes is adequately attenuated and the polarity skew offset can be optimized the the servo for each satellite and polarity.

Otherwise, you are on the right track. Make yourself skinny and step away to verify signal gains or losses. The older I get, I do find it harder to make myself skinny in the side profile.... :D


Brian Gohl
Titanium Satellite
No matter which way you turn a round object,it's still round,and I should know :D:popcorn
 

Vallenato

SatelliteGuys Pro
May 25, 2011
221
10
America
.
West/East deviation can be fixed always creating another satellite on the receiver list and positioner controller. I do that for example with 97W and 98 W.
.
Do you catch 40.5(circular) & 97.0W (linear) in the same motorized 6 ft antenna??:eek:..or You are talking about other dish for 97.0W:rolleyes:
 
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