One Meter Primestar Mini-Bud Experiment

[updatelee]

I would be interested to see how a real cband feedhorn and lnb work on this. the c/ku lnb's arent exactly known for their stellar performance.

 

[linuxman]

Thanks for the entertainment Fred. This thread has been informative and satisfying, with lots of good and useful ideas. Although most of us know it's not practical to use such a small dish for C-Band, we also know it can get C-Band and it's fun to experiment with. It's even fun to read about it. Good job, and keep the fun coming. I'm now waiting for your next project. I'm sure it will be enjoyable, as they always are.
Thanks Fred..!!!

Thanks Al!

I appreciate the encouragement as always.

As for you Mr. Lizard, what are you trying to do, work me to death? :yikes:

- shouldn't the scalar be flush or ahead of the leading edge of the LNBf? (closer to the dish

I don't see anything that would prevent testing that theory, ...
...and if you could pick up a few points on C- it'd be well worth it.

Yes, if I was trying to create the proper F/D ratio, but not easy to do with current support arms. I would need to move the scaler forward, and would have to build extenders on the scaler to allow room for the LNBf behind it without hitting the support arms.

- there looks to be room to slide in a conical scalar without any hacksawing to it.
Reports from 2005, when this project was first tried, did indicate a noticeable improvement with one.
Again, a few more points on C-band is the goal, as you seem to have adequate if not outstanding Ku.

By all indications, a conical scaler would probably fit right in, and might gain a few points on C-Band. If someone has one they want to get rid of, or know where to purchase one, I would be interested.

As for your success, it's hard to know what to credit it to.
I'm sure careful alignment played a big part! -

- it appears the 1m round dish may have an advantage on the elliptical 84e's
Perhaps we can chalk this one up to: Size does matter. - - ?
Or maybe the area?

I think it is mostly due to size for the C-Band. The 84e does a great job on Ku.

- over the years, I thought users found the BSC-621 at least adequate for C-band.
Is the CK-1 really better?

- over the years, I thought the BSC-621 had been lackluster for Ku, ...
...and poor at getting both C & Ku to focus at a common point.
Is the CK-1 really better?
You did have some pretty good success with the CK-1 on one of your Birdviews, last year.
Was that because the CK-1 is a better product, or just very careful tuning?
It was on the big (how big is it?) Birdview scalar?

As to which LNBf is better, I can't answer. I don't have a BSC-621 to try out.

One thing I am sure of, is that I am no better at tuning a dish than some of the members on this forum who own a 621, and have had limited success. That should speak volumes about the quality of the two.

- do you still have a baseline set of signal/quality levels from Ku and the original 1m Primestar LNB?
That would tell a lot about how the dish/CK-1 combo was performing on Ku.
It's a shame ya don't have a duplicate dish, with the stock LNB . . . or any other Ku LNB, to compare.
I'd like to see how an Invacom or one of your Sky Mexico compare to the CK-1 on Ku.

From an earlier post in this thread edited for those who prefer location rather than satellite names:
The first numbers are with the OEM Primestar LNBf, the second with the CK-1
129W G27 11964 H bouncing between 80 - 85% SQ *********60% SQ
127W G18 11720 V is rock solid 60% SQ ********45% SQ
101W AMC4 11860 H is rock solid 75% SQ ****60% SQ and 11916 H is 99% SQ***75% SQ
91W G17 12060 V is rock solid 90% SQ ***** 75% SQ
87W AMC3 11716 H is a solid 90% SQ ***** 75% SQ
74W H2 11734 H is a solid 75% SQ was at 90% ****** 60% SQ
2W AMC6 12053 V is a rock solid 90% SQ ******* 75% SQ

So you can see, there is a drop in Ku Signal Strength/Quality.

- back on C-band, what about your receiver sensitivity? Using a Pansat 2500a?
Got anything more common so that other users can compare with ?
Perhaps a Visionsat IV-200 or a Coolsat 5000?
Or, whatever the 120cm C-band folks are using - -

I did a factory reset on my Fortec Star IR5400NA and am scanning in a few satellites now.

The FS shows a 25% SQ for EWTN 3920 H 91W G17, where the PS 2500a had that channel at 15% SQ. Both pictures are too pixelated to watch.

T FS shows 53% SQ for the 12060 V Ku test cards on G17 91W where the PS showed 75% SQ.

It appears so far, that the FS shows higher C-Band numbers, and lower Ku numbers, but the channels display are about the same.

Last category:

- where is the adjacent-bird interference?

- or, are we just fighting for any signal at all?

I am just fighting for channels and signal period. I haven't scanned in enough C-Band channels to see, but I am sure there will be bleed-over.

For Satcom:

Experiment conclusions

Too bad you've wrapped things up, I wanted to send you my BSC-621-2 for comparative purposes.

The wrapping up is primarily for conclusions, further possibilities, and brain-storming. I am always open to further experiments, and if you or anyone else wants to send me a BSC-621, I'll give it a fair shot.

As I said, I don't count myself as being any better than anyone else on this forum for tuning dishes. Am I careful and slow? Yes, but so are most other people who are successful at tuning dishes. Patience in these projects will always produce good results.

Did you give any thought to the speed at which one could change C-Band channels on a mini-BUD vs. a big 10' Prime Focus C-Band, lumbering, dish?

My prime focus dishes move across the sky at about the same speed as this dish lumbers.

 

[Mr Tony]

Thanks for the entertainment Fred. This thread has been informative and satisfying, with lots of good and useful ideas. Although most of us know it's not practical to use such a small dish for C-Band, we also know it can get C-Band and it's fun to experiment with. It's even fun to read about it. Good job, and keep the fun coming. I'm now waiting for your next project. I'm sure it will be enjoyable, as they always are.
Thanks Fred..!!!

+1 :up:up

always nice to see folks tiunkering with stuff to see what they can get

 

[Mr Tony]

also being in the center of the US does help on C-Band as that is the "sweet spot"

Here in MN I cant get as good of signals

 

[WillardG]

thanks fred-ster:

 

[linuxman]

also being in the center of the US does help on C-Band as that is the "sweet spot"

Here in MN I cant get as good of signals

Yes it does help greatly!

I can pretty much reach the best of both East and West from my location with pretty darn good signal, and I am so glad I have at least two spots on my roof that give me that full LOS.

Thank you WillardG!

 

[Mr Tony]

no what I meant was signal strength wise you're in the sweet spot. If you look at Lyngsat and click on the "supposed" footprint in alot of cases you are in the sweet spot and need a smaller dish then me. Now some of those are goofy as I think one said I could get good signal witgh a 76cm dish but in alot of cases the signal would be stronger in St Louis

 

[linuxman]

no what I meant was signal strength wise you're in the sweet spot. If you look at Lyngsat and click on the "supposed" footprint in alot of cases you are in the sweet spot and need a smaller dish then me. Now some of those are goofy as I think one said I could get good signal witgh a 76cm dish but in alot of cases the signal would be stronger in St Louis

Ah!

You are right about that too! I hadn't ever thought of it that way before.

 

[Mr Tony]

thats why when folks post their quality readings they can be so different due to the satellite footprint

 

[linuxman]

thats why when folks post their quality readings they can be so different due to the satellite footprint

When you combine that thought with the different meter readings from a dozen different receivers, it becomes a crap-shoot on who is getting the best signals.

 

[linuxman]

I would be interested to see how a real cband feedhorn and lnb work on this. the c/ku lnb's arent exactly known for their stellar performance.

Hi Updatelee,

Sorry I didn't see your post yesterday. It must have been posted close to the same time as one of mine.

In order to put a Co-Rotor, or some other "real"cband lnb, I will have to make the adapter a lot more stable than it is right now. I do have an older HTS 35K real voltage controlled LNBF that I think would fit into the scaler. It isn't quite as heavy as a Co-Rotor and LNBs combo.

It has started to warm up here, and will cool back down on Wednesday significantly with rain etc., but Friday and Saturday will be very nice and dry. I am going to try and manufacture a more stable adapter, and re-tune everything.

I did re-do my current adapter and moved the scaler closer to the dish and the LNBf is now recessed into the scaler for a higher F/D ratio. Focal distance is still the same.

There is no change in Ku signal for better or worse, but the C-Band signal has improved a good bit. Probably at least 5 - 10% SQ across the satellites I have programmed in. But being further from the ends, the adapter is less stable than yesterday.

I now have channels on 72W AMC6 C-Band. Pixelated badly, but they are there. I couldn't get them to scan in yesterday.

Here are pics of the recessed scaler:

 

[Lak7]

Linuxman-
Is it possible to make an array of small dishes with C Band LNBFs to improve weak signals, like NASA does when looking to ET radio freqs?

 

[linuxman]

Linuxman-
Is it possible to make an array of small dishes with C Band LNBFs to improve weak signals, like NASA does when looking to ET radio freqs?

Hi Lak7,

I don't understand what you are describing as an array, so I can't comment on the feasibility.

Sorry!

 

[Lak7]

2 (or more) Dishes pointed at the same Sat feeding 1 receiver.

 

[linuxman]

2 (or more) Dishes pointed at the same Sat feeding 1 receiver.

Hmmm!

You'd need someone smarter than I to figure out how to hook it up, but I don't see why it wouldn't.

 

[SatPhreak]

An array is not a simple thing to set up. It needs all the lnbs to be run off of a single LO, so you need to be able to modify all lnbs. If not one lo might be off from the others and thereby it will be off frequency which will result in a lower signal level if any at all. Secondly the cabling from each lnb will need to be tuned so that when they enter the combiner they are all in phase. This will need to be done to 1mm accuracy for the cable lenths assuming that all dishes have the same focal length, or more tuning involving an osilascope to get them all in phase. If not the out of phase signals will add up to less signal than one dish or the other. Thirdly rg-6 is out and rg-11 will be needed.

Not really somthing anything I would try. I got as far as researching it a little and left it at that. Paraphrasing the answer of someone that has tried 'doubling the size of the dish is easier and cheaper everytime, and gets a higher signal because of the inverse sqare law'.

Arrays are really only worthwhile if the original antennae size required is qreater than 10-15m (33- 50') at arourd that point it gets economically feasable. C-band in NA never gets close to that point.

Making your own conical scaler probably would be an option to increase signal on a sub marginal sized offset dish.

 

[Anole]

home-brew scalar discussion

Making your own conical scaler probably would be an option to increase signal on a sub marginal sized offset dish.

Looking through the old threads (back to 2005), I found measurements and dimensions of conical scalars which worked.
However, there are no drawings, and interpreting the numbers might take a bit of head-scratching.
Not impossible, I' m sure.
And of course, some experimenting is probably in order, so what the heck, eh?

I have a buddy with a lathe in his garage.
However, to ask him to decimate a big chunk of aluminum without good numbers, just never seemed a wise move.
Nor a cost-effective move, either.

I thought about making one with brass shim sheets, a big pair of scissors, and a really big soldering iron or small torch.
If it's stout enough to be bolted to the dish arms, and hold up the LNB, it might be heavy.
If the LNB is bolted to the dish arms, then the scalar would only have to support its own weight , and sit upon the LNB.
Very thin metal should suffice.

Steel? Well, not out of the question, but how do you work it and how do you connect the pieces, assuming you make it out of a number of parts?

I'd considered pop-rivets to hold the parts together.
They are generally aluminum, so their strength, and galvanic corrosion potential, might matter.
Plus, they're not flat on the top, and certainly not flat on the other side, so how/where would you use them?
It did occur to me that they might be used in less critical areas, or to hold the parts together while they were being brazed, welded, soldered, or glued.

I did discuss casting of aluminum.
That's not totally out of the question, at least to try.
And it might be the most simple for building a bunch of scalars.
But again, measurements , measurements, measurements.

If we could metalize plastic, then we could make them from casting resin (and maybe a bit of fiberglass...
Better for experimenting, and safer than melting aluminum.

Lastly, there's a member here getting some sent in from his brother in another country.
Unfortunately, all the shipping, handling, and markup comes to the usual price: $50.
If I wanted to spend that much, I'd have done it long ago!

Due to the small demand, our two sponsors have both bowed out on the question of conical scalars.
And in other threads, I've documented the price overseas of complete C-band LNBF with flat scalar in the $3 to $10 range.
(without looking, I think it was $3.50 for one output C-only, and $7.50 for two output C-only)
One is being imported now, and sold on eBay for ... $17... ?
Which, in my opinion, suggests that a conicall scalar for $20, delivered anywhere in North America, should be a possibility.
Just find an offshore plant building them, and they'd be happy to send in a few via air mail for that price. -

 

[linuxman]

Well, I think the array is out of the question for this project.

As to the conical scaler, I am not doubting that the signal would improve. Just moving the flat scaler I have improved the signal a good bit, and it is hacked to pieces.

I could probably jam one together from old scalers here, but really don't have the metal cutting equipment for a project that size. Just have to see if one is available somewhere.

I just got back from Lowes, and have an idea for making the scaler much more secure since I now know where it's final resting place is. So hopefully tomorrow morning before it gets hot again, I can make my modifications, and be ready to fine-tune again. The fine-tune might have to wait until later in the week when it is much cooler with highs in the low to mid 70s Wed through Monday.

 

[gremlin411]

Anole if you find some please pm me with where I can get a couple. are if figure out how to make them please share the design I need two.

 

[SatPhreak]

Check out http://www.w1ghz.org/antbook/chap6-4a.pdf about conical feed horns. Even a conical feedhorn made out of copper sheet (or similar material) gains up to 10% over aflat one designed for a f/D of .3 could get. Basically it is made for shallow dishes (f/D .5-.8)to optimize the planes of the lobes of the signal.

I did find a link to a hack site (search google for conical scaler) where somebody using a 1m dish on c-band made and installed it and got about 10% increase in signal. This was on many cband channels and sats. He then tried it with a 76cm dish and still managed to get 2 channels on c band. He tried many different sizes and angles of cones to get optimum results.

A corragated conical scaler would work even better but would be harder to make.

I think I now need to get a c band lnb and try this for myself.