Skewing the Geosat Pro CK1 LNBF

[truckracer]

You numbers don't look too bad. Looks like you have ku coming in well. My ku just didn't do very well at all with the BSC-621 on my 10' sami. I ran stings on the dish and it was not warped. I was trying to blame my install first.

Your Geosat seems to be doing better on ku than my BSC-621.
My combo unit seemed to be frequency dependent where it fell off. any TP that was 11xxx Mhz came in pretty good. anything that was 12xxx Mhz i could hardly lock at all.
this was especially noticeable on G25 KU on my 10'. I think Mike Kohl has the right idea that you have to compromise on these
units. Being that Ku is "harder" to get I would just let c-band be a little lower since it does not suffer from rain fade as much.

I have never lost a c-band signal on my 10' dish when it was pouring the rain to the point you could not see two feet out the
window for all the downpouring rain. Ku of course was all but non-existent. I guess we need the most head room in the ku department.

 

[gabshere]

I realigned my BSC621 ( after i took out the c-band isolation bar) but my install was without tuning so hopefully i will get some time to make that tuning.......

the above isolation bar on my BSC621 ( and i took pictures befor and after and will probably post in another thread) anyway the isolation bar looked to be blocking the focal point for KU and also covered one of the probes ( albiet it was about three inches below the KU probe) i still suspect it might have blocked the KU focal point for part ( one polarity).

when i get the fine tuning done i will post my results ( in that new post to compare ) i have a coolsat 5k & traxis ( no pansat)

I did compare the CK-1 pictures with the BSC-621 and will make this note :
1) the CK-1 has no isolation bar to block or interfere with the signal
2) the CK-1 KU probes are aligned to corrispond with the C-band probes , the BSC-621 KU probes are opposite (this is a major item and i have no way to correct ) I tried to align them to equal the c-band probes and can't. I would just about consider this a design flaw. Although the Technical bulliten shows the probes aligned the same. I will have to re-check alignment to see if the probes will align ( and forget the KU isolation bar alignment like the technical bulliten.) so they might alighn but it would throw the isolation bar off and not be like the pic in the technical bulliten.

I will post more items as i discover them

 

[linuxman]

Thanks George and Truckracer!

Of course I have been mulling this over in my head all night to try and figure out what it needs to get the C-Band signals up across the arc.

I have excellent C-Band on G11 which is my TS Satellite. C-Gand also seems to be good on the nearer satellites in the center. The farther out in either direction, and the C-Band falls off some. Ku seems to hold fine even at the farther limits. Hispasat is like it is next door.

I will check everything shortly as far as plumb if something shifted, and re-check declination/elevation both at center and on the ends.

It is my theory in my mind that the Ku will be good on this dish even if coming off-center a little which might account for lower C-Band signals on the outer reaches of the arc. I don't know, but will find out.

 

[linuxman]

My plan to get on the roof was thwarted by a service call earlier, and I have another place to go to in a short while.

Looks like my next window of opportunity will be Wednesday afternoon, and then maybe Saturday after that. The monsoons are starting again.

 

[truckracer]

I put on my corotor and couldn't be happier. I am leaning toward thinking the c/ku lnbfs work best on smaller dishes 8' and smaller. I think the tight beamwidth on most 10' dishes don't allow enough fudge room for design compromises.

Looks like you have tuned probably about as good as it gets (I know us die hard satellite guys shouldn't say such a thing - LOL).

 

[gabshere]

I put on my corotor and couldn't be happier. I am leaning toward thinking the c/ku lnbfs work best on smaller dishes 8' and smaller. I think the tight beamwidth on most 10' dishes don't allow enough fudge room for design compromises.

This is good to know as i will be trying my other bsc621 on my 10 ft odem mesh dish later this spring.

 

[linuxman]

My Gbox hiccuped last night, and I had to do a factory reset.

Back good as new now, but I had to re-program in all the satellite positions. I am glad that it did really because it gave me a chance to carefully go through and find the best signal on each satellite using the Ku signals where possible.

I started out this morning trying to figure out a way from inside that I can straighten this whole thing out because it is raining and I can't take the whole tuning setup to the roof.

I finally remembered something Brian Gohl from SatAV said to me (at least I think it was him) when I first got the CK1 and I was asking him where the arrow should point. The easy part I remembered about it being 9:00. The part I forgot until today was moving the dish to G15 (G1 on analog) and let the DVB receiver control the polarity and change between channels 11 H and 12 V. Two channels next to each other that have opposite polarities. Turn the CK1 until you have good signal on both with no sparkles or artifacts from the other channel, and the polarity is set.

So this morning I hooked up my new (only hooked up a time or two) US Legacy (Drake 1524) analog receiver to the dish using a DC blocking splitter, and lo and behold, I have channel 11 H, but no sign of channel 12 V period. That's why the Traxis is having a hard time locking the vertical C-Band channels. I don't know how the Pansat did it.

If it doesn't screw up the Ku side, this may make quite an improvement on the C-Band side.

Radar shows a break in the rain in a couple of hours. It will only take a few minutes to run up and adjust the skew on the CK1.

 

[gabshere]

let us know and if you can get some pictures

i'm working up a BSC621 tread and it will be interesting hopefully with pictures of a old BSC621 and the new type.

although the pictures in the tech bulliten show it one way, my old BSC621 wil not align like the photo. The ku on new BSC621 wil not adjust. so only adjustment is for the whole unit.

 

[truckracer]

I am going to have a bit of a problem with my analog receiver when all the analog channels are gone- sort of.

When adjusting skew, if I am on a channel that has snow where there is no signal I cannot see the adjustments or know for sure the buttons i am pushing are doing anything.
I can't keep my blue background screen up on a static channel.

I have an orb 7500 c/ku analog.

That's a great idea for tuning.

 

[linuxman]

let us know and if you can get some pictures

Pictures might have to wait for a better day, but I will get them.

I was just sitting there playing back and forth with the analog and I have it fixed where my son can change the channels on the analog, and change the polarity with the Traxis without having to change to the Traxis screen, so he will be doing that blindly. But doing that, I can see the vertical flash in when changing the polarity, so it won't take much.

I think I can reach the LNBF with the dish at G15 especially if I take the 3 foot step ladder to stand on. I want to be able to change it while he watches and changes channels. It will save me a lot of trips.

i'm working up a BSC621 tread and it will be interesting hopefully with pictures of a old BSC621 and the new type.

That should be interesting.

Maybe between all of us, we can have a working procedure on both.

 

[linuxman]

Truckracer,

Set the Co-Rotor with the Ku LNB at the 10:30 or 11:00 position on the dish while at your True South Satellite.

Set your skew on all satellites to +45 and -45 (will be different whether H or V is plus or minus because some satellites are "normal" and some are "reversed" polarity) and skew each satellite individually from there.

 

[truckracer]

Thanks Linux, I will go through and do the +/- 45 then peak the skew on the whole feed assembly. That way it will work sort of like an lnbf except for amc-1KU I think.

 

[linuxman]

then peak the skew on the whole feed assembly

I wouldn't touch the assembly after adjusting the skew.

If you want an LNBF, use your BSC-621!

 

[linuxman]

Finally! Whew!!!

Had to overcome some hills to make everything work. I finally figured out why the Vertical C-Band channels wouldn't lock on the Traxis and Coolsat. I had the Verticals working at the dish yesterday afternoon on the Traxis, but wouldn't lock inside the house.

Therefore the analog wouldn't lock the Verticals either. The problem was too many slaved connections. I ran direct from the dish to the DC blocking splitter etc and finally got a lock at the TV on the Traxis and the analog.

In between showers and taking my son to town, I got the CK1 skewed properly. Got a 239 on channel 12 V and 240 on channel 11 H. That's out of 255 max on the Legacy (Drake) That old Drake has a great picture Al. Almost better than the 4DTV.

While I was in town, I stopped by Skywalker and picked up two - 2 port "Diode Steering" power splitters, and one 4 port "Diode Steering" power splitter. I now have the 4 port hooked up and the Twinhan, Coolsat, and the Traxis run through that with very little signal loss on anything.

The C-Band and Ku signals has improved across the arc. I might need just a little elevation adjustment on the ends, but NASA on AMC7 is now at 70% SQ on the Traxis, even with rain showers. For some reason the Equity mux on G3 wouldn't come in for me this evening. Very low SQ 17% SQ only. Have to figure that out unless they were down because of storms.

All in all, it is coming together nicely with outstanding Ku and excellent C-Band signals across the arc. I will take the Pansat to the roof one last time either tomorrow afternoon or Saturday depending on the weather and get final readings for the chart.

 

[voomvoom]

That old Drake has a great picture Al.

:up::up

 

[linuxman]

HeHe!

I agree!

 

[linuxman]

Well after changing the skew late yesterday and finding myself without the Equity mux on G3, I spent a couple of hours on the roof this afternoon trying to get it back.

I made an interesting discovery. Keep in mind that I spent most of the week-end moving the scalar/CK1 assembly further away from the dish to get the Ku and C-Band to meet at some high point.
I wrote the following earlier:

I ended up at 40-7/8" for the final Focal Distance. I was at 40-1/2" when I left it Saturday.

In the process of trying to get some C-Band signal back after the skew, I started moving the CK1 only out of the scalar and closer to the dish. It is now sticking out of the scalar a full 1/2 inch. So that is 40-3/8". I am basically where I was over the weekend minus the scalar. It is still at 40-7/8".

Here is a comparison between todays readings and the ones I took on Sunday evening before the skew. The comparison is only between the Pansat readings Sunday and this evening with the GeoSat CK1 and the solid Birdview.

--------------------------------------Sunday reading--Today's reading
AMC7 - 137W 4060 V C-Band-----45% SQ------------60% SQ
G15 - 133W 3745 H C-Band-------15% SQ------------45% SQ
G27 - 129W 11964 H Ku------------63% SQ------------75% SQ
G10 - 123W 11718 V Ku------------75% SQ------------75% SQ
G3 - 95W 4039 H C-Band Equity--60% SQ------------30% SQ was 0% after the skew last evening
G11 - 91W 3720 H C-Band---------90% SQ------------90% SQ
G11 - 91W 3858 V C-Band---------75% SQ------------75% SQ
G11 - 91W 12062 V Ku-------------75% SQ-------------75% SQ
AMC3 - 87W 12144 H Ku-----------75% SQ------------60% SQ
AMC2/16 - 85W 12195 H Ku-------90% SQ------------90% SQ
G17 - 74W 11734 H Ku-------------90% SQ------------99% SQ
AMC6 - 72W 12053 V Ku-----------99% SQ------------99% SQ
AMC6 - 72W 4043 V C-Band-------60% SQ------------45% SQ
IS9 - 58W 4040 H C-Band----------90% SQ------------90% SQ
IS3 - 43W 12048 H Ku--------------75% SQ------------75% SQ
Hisp - 30W 11883 V Ku-------------75% SQ------------30% SQ
Hisp - 30W 12171 H Ku-------------90% SQ------------45% SQ

By moving towards the dish, the LNBF is seeing less of the surface than before, but higher C-Band signals with little change to Ku except on AMC3 and Hispasat. The other Ku signals remained the same or went up.

I had to click East on almost every satellite to get the best signal.

So what is the difference?

Hispasat dropping like a stone has maybe given a clue as to what is needed for more tuning?

Look at the numbers and tell me what you think the dish needs. I want to get the Equity mux on G3 back.

Tell me how. I think I know what is needed, but I want to read your opinions.

 

[voomvoom]

Looks to me as if your Azimuth is off? You need to twist the dish on the pole one way or the other?
You don't seem to be following the ARC?

Edit: maybe you declination is off? Or perhaps the pole isn't plum?

 

[linuxman]

Looks to me as if your Azimuth is off? You need to twist the dish on the pole one way or the other?
You don't seem to be following the ARC?

Edit: maybe you declination is off? Or perhaps the pole isn't plum?

Thanks Al!

I found part of the problem today.

I had forgotten to put the cap back on the end of the LNBF, so I tripped up there between storms and took along my tape measure, my laser pointer, and my allen wrench.

I first measured the 4 sides (top, bottom, East, and West) to see how far out it was sticking and it was all equal. I didn't have my laser pointer up there with me yesterday. Sure enough, it was out 1/16" more at the top than the bottom. 9/16" at the top, and 1/2" at the bottom. Put the laser pointer on, and the laser hit about 1 inch below the center cap (about 2 inches off center). Loosened the set screws up, and pushed the feed up just a little and tightened back down. Now perfect on the center cap.

I can't stress enough how important having that feed-horn centered perfectly with the mouth parallel to the center of the dish.

Centering it up gave me back Hispasat with the same signal I had previously and gave me another 10% SQ on the Equity G3 mux.

That movement should also give us a clue to what is needed with the dish for the top of the arc to get it's best signal bringing the Equity mux full power.

Remember just two inches higher on the dish surface gave me Hispasat back and higher signal on G3.

What does the clue tell us?

 

[gabshere]

when you say Centering any you saying the feedhorn was crooked in the scaler ?

i still have to make a laser tool