ku bad on 10 footer

[truckracer]

We had a lot of rain today and my KU band just sucked bad.
checked ku on my 7.5' - booming in (storm and all)

I did the string test and the strings just barely touched. No space but not tight across each other.

Is this an accurate way to test for warpage?

Could my dish be off enough to not get ku? My c-band booms in on all sats.
I have my dish tracking the arc.

My g10 r KU is good, amc-4, amc-3, g25 ku is terrible. I can pull up and down on the dish and it disappears.

I want to blame the bsc-621 but it was all good before the rain.

Oh well I will try later.

 

[Anole]

Do you think there might be a little condensation in the BSC-621 after the rain storm?
Maybe that one is more touchy for some reason, than the one on your 7.5' dish?
A sunny and dry day or two should tell.

I've been kinda following your saga, and expected the bigger dish to outperform the smaller one.
Suppose it's possible that there's a lot of production tolerance between the two LNBs?
I hate to suggest swapping the two, but if the lack of performance persists, then maybe it is the dish, and maybe it isn't the dish.
I got the other brand, after reading Linuxman's lengthy test report and alignment thread.
If you had both brands, you'd be in a perfect position to evaluate 'em in two different environments: the 7.5 and the 10 foot dish.

 

[tvropro]

How's the surface of the 10 foot? Is it ku mesh? What's the efficiency rating on ku for that dish? I know that some buds were better performers than others for ku. If your working well on one satellite and not others there is a tracking error. Possibly are you tuned to a sidelobe on ku vs the main beam?

These are a few things you may want to check out.

 

[truckracer]

I do think I was tuned to a sidelobe- I could bump the positioner a couple of clicks and have poor signal, bump in the same direction another click-lose signal, Keep following me here- bump another click and boom better signal but none great.

No singal-some signal-no signal-decent signal. Of course with a satellite you are usually either dead on or not. Sidelobe action here I think.

tuned on it today and here' s the results. Very odd.

On ku- Amc-3 , PBS channels are almost un watchable. Horizontal tp's come in pretty good. Skewing the lnbf did not help. My ku band is like that all the way across the arc. Some tp's almost 100%, some lousy.

C-band is stellar all the way across. Any lifting or lowering on the dish cuts the signal.

My 7.5' has my homemade c/ku lnbf combo.
My 10' has the BSC 621.

 

[Anole]

oops

Sorry, I was thinking you had a BSC-621 on the 7.5 foot dish, too.

Now I recall your Frankenstein LNB
You still owe us pictures! -

How do you feel about moving it to the 10' ?

edit: oh, wait... the 10' dish has the modified BSC-621 you discussed in another thread?
It's getting hard to keep up with all your creativity!
So, all the more reason to wonder if it's the dish or the LNB...

 

[tvropro]

I do think I was tuned to a sidelobe- I could bump the positioner a couple of clicks and have poor signal, bump in the same direction another click-lose signal, Keep following me here- bump another click and boom better signal but none great.

No singal-some signal-no signal-decent signal. Of course with a satellite you are usually either dead on or not. Sidelobe action here I think.

tuned on it today and here' s the results. Very odd.

On ku- Amc-3 , PBS channels are almost un watchable. Horizontal tp's come in pretty good. Skewing the lnbf did not help. My ku band is like that all the way across the arc. Some tp's almost 100%, some lousy.

C-band is stellar all the way across. Any lifting or lowering on the dish cuts the signal.

My 7.5' has my homemade c/ku lnbf combo.
My 10' has the BSC 621.

Sounds like your tuned to a sidelobe from your description. C band would be fine because its 3 times less critical then ku. You may have declination issues also. The bigger the dish the more critical to find that sweet spot. That's one of the reasons I left my 12 foot for C band only. It's very very touchy on c band. On ku I'd be pulling my hair out I think.

 

[linuxman]

The bigger the dish the more critical to find that sweet spot.

The bigger the dish, the more difficult to tune for Ku and get the same results across the arc.

There are many factors to take into consideration.

It took me a long time to finally get what I wanted out of my 10' Unimesh, and today I took it down to make way for the perforated Birdview dish tomorrow. The Unimesh is a good dish, but tomorrow it goes back into storage.

 

[truckracer]

thanks for the replies

I am going to get a digital camera this weekend so you can see my pics.

I know the beamwidth on this big dish is really tight on ku.
I still want to blame the 621 but I could be wrong.

I have never had an lnbf that was so touchy on the skew. It seems like on ku you can never get both polarities to work at the same time.

I am going to try a corotor or bullseye type feed with a servo.
Any advice on what works good?

I may just run my 76cm patriot dish with a ku lnbf. I have an SG2100 motor and extra v-box laying around. I can do it that way.

I was just hoping for some big numbers on ku band with that big dish.
I thought sure it would blow away my small dish.

 

[linuxman]

Any advice on what works good?

If you can find an old Co-Rotor with the ADL patent infringing design, which are few and far between, they are the best. I have never tried a Bulls-eye, but the newer style Co-Rotors work reasonably well.

If you want to stay with an electronically voltage controlled LNBF, I recommend the GeoSat Pro C/Ku LNBF.

 

[tvropro]

If you can find an old Co-Rotor with the ADL patent infringing design, which are few and far between, they are the best. I have never tried a Bulls-eye, but the newer style Co-Rotors work reasonably well.

How about the the ADL-RP1-CKU ADL feed. I got good results with it on a clients 10 foot Winegard a few years back. I have the RP1-C feed on my Unimesh and love it. I know some people like the co-rotors better though. Mike Kohl seems to like the ADL feeds from what I heard in the past. Maybe Mike can add to the pro's and cons of this feed over a co-rotor.

 

[mikekohl]

The RP-1 C/Ku is a far better feed...but must be approached very carefully.
It is a cast (non adjustable) design that works well on f/d ratios between 0.35 and 0.42. What you must do is install some external adjusters to manually find the hot spot of the focal point. Another factor is that the feed plate is about 7/8 inch thicker than what you find on the Corotor or the ADL RP-3, so that must also be compensated for.

The latest RP-3 adjustable scalar units are pretty good, and should be considered if you are only comfortable with an adjustable scalar type device.

ADL had some bad press in the past due to ignorance on the part of many installers that were not familiar with the concept of external adjusters on the RP-1 as well as the deep dish RP-2 versions. Some people still insist on adjusting the f/d ratio to find the strongest signal (and the focal point), and do not realize that like this works much like focusing a traditional 35 mm camera. This may be an acceptable way of finding the focal point, but with an adjustable feed, you also need to measure that precise distance from the front edge of the antenna, set the f/d ratio for that recommended by the antenna (I believe the SAMI was around 0.40), and manually adjust the entire assembly to return to that focal point.

The same concept applies with the RP-1 and RP-2 ADL feedhorns.
Adjust your quad legs all the way out. Install four 1/4 inch X 3 inch slotted round head machine bolts at 90-degree points through the front of the feed plate. Tightly wrench a 1/4 inch nut on the back side of each. Spin another 1/4 inch nut and a 1/4 inch flat washer to within about 1/4 inch of the already-installed nut. Slide the assembly into the ends of the four quad legs. Install another flat washer and 1/4 inch nut on the back side of the quad legs.
Your mission is to now manually finger-adjust the hardware to carefully center the feed and set it to the textbook focal distance. The improvement over an adjustable scalar type will simply blow you away, once you find the magic spot.

 

[truckracer]

A very interesting concept. So what you are saying this feed does not "slide" in and out of the scalar ring like I am used to with lnbf's. It is all one piece and you have to create studs with jam nuts to find the sweet spot by moving the entire assembly in and out scalar and all.

That may actually be worth a try with my lnbf. I have tried most everything else.
I could set the "theoretical" f/d between the lnbf and scalar. Then move the entire scalar in and out to find the sweet spot.

Would this be a waste of time?

 

[truckracer]

Is the Geosat c/ku lnbf the same thing as the bsc-621?

Is it a different design? (same concept).
Voltage controlled switching would be much better for me. I like the seemless automatic polarity switching when flipping channels instead of having to flip channels on the analog receiver to change polarity.

 

[tvropro]

The improvement over an adjustable scalar type will simply blow you away, once you find the magic spot.

I used a Chaparral Pr1 AS before the RP1-C. The performance was much better with the ADL vs the Chap.

You are right Mike about the bad press the ADL still gets. It's because people don't understand the proper way to set up a feed. I always recommended the ADL feeds but some just don't get it and bad mouth the ADL. I guess it's the old saying some people think they know what there doing and some people know what there doing

 

[linuxman]

I'm glad you explained it Mike. I was going to take a stab at it, but I thought I'd see if you posted first.

I still need to try that process with my Pinnacle.

 

[gabshere]

Is the Geosat c/ku lnbf the same thing as the bsc-621?

they are very much alike when i talked with a couple of dealers , i found out that the basic difference is the Geosat is a bit heavier and seems a bit sturdier in design, I haven't compared the two in preformance but suspect the results to be very close.

when i compared the c-band only lnbf's Geosat pro C1 & the ASC421 , i found that the ASC421 seemed lighter, smaller in diameter with a thin layer of paint on the scaler & lnbf. The Geosatpro C1 clocked in slightly heavier with a nice layer of paint and the metal used seemed sturdier on the lnbf & scaler. the results for each were close.

i didn't get to test them in weather extreams but i did like the Geosatpro C1 for its sturdier build. this is one area i worry about my BSC621 for all the times i tighten & loosen the lnbf from the scaler. i figure eventually i will have problems weaking the metal.

another option if you like the corotor type is that some pansat receivers control a corotor polarity switching

 

[tvropro]

I'm glad you explained it Mike. I was going to take a stab at it, but I thought I'd see if you posted first.

I still need to try that process with my Pinnacle.

I used the RP1-CKU on a Winegard Quadstar. The Pinnacle is a very deep dish, I think the F/D is .27, the Quadstar was around .38 if I recall. The feed worked great on it.

 

[linuxman]

The Pinnacle is a very deep dish, I think the F/D is .27,

The Pinnacle is a .28 and yes it is a very deep dish.

The CK1 is rated to a .28 and may just do as well as the standard Co-Rotor. I am going to find out one of these days.

 

[mikekohl]

ADL RP-1 is rated from 0.335 to 0.42 f/d ratio
ADL RP-2 is rated from 0.275 to 0.335 f/d ratio.

The RP-1 shines with f/d ratios higher than 0.35.
When you get close to the cutoff (0.335), one could go either way.
I used the RP-1 on an oddball creation at Orbitron, which started as the SST-8,
an eight foot sectional antenna. We took a metal shears and cut it back to the first inner ring, so that the diameter was 69 inches. In doing so, the f/d ratio jumped to 0.46, which was uselessly flat and full of sidelobes on a conventional feedhorn such as the Polarotor 1 or Corotor II. But the RP-1 had enough sidelobe reduction that it made this "SX-6" antenna work very well.

The RP-3 covers an entire range from 0.32 to 0.42.
Deeper dish uses an "Aperture Iris", which has the same concept as the
Chaparral Gold Ring, but the Aperture Iris is literally placed under the plastic
front feedhorn cap, and sharply sculpts a narrower view of the antenna,
which then better matches a deeper dish.

 

[truckracer]

wow cutting down a dish- I didn't know you could do that