Primestar 84E/BSC621-2 LNBF Experiment

[satcom1]

Offset KU on ! meter dish

This makes perfect sense to me, intuitively. Since obviously you get the strongest reflected signal at the center lnbf (excluding Torroidal DIshes), then the C Band lnbf would really need to be in the center for mini BUDs.

So if you have a 1 meter round offset or better the KU signals should be still providing a very strong signal.

Only problem is if you want KU offsets East and West then the Scalar ring will need to be cut out more.

The flat Scalar only produced about 1%-2% SQ improvement on the BSC621-2 so it might not even be necessary. On the B1 Sat Stack it was critical.

 

[bloomdog]

Here are the calculated results for a C-Band Conical Feedhorn with a center frequency of 5.15Ghz and a 62MM Dia. waveguide.

5150 MHZ
15dBi gain
144.2 mm Aperature Diameter
62 mm Diameter LNBF
54 mm length
Cone angel of 37.3 degrees

A paper template can be laid over copper or aluminum sheet, cut out and rolled up.
Solder or pop rivets. I used Super Glue and Painters tape to seal the seams. When the glue sets hard (12 hours) remove the painters tape.

You can download cone pattern programs that make a template on your printer.

1. How did you arrive at the values (other than the diameter of the lnbf)?
2. WHy did you use 5.150 GHz? The frequencies of the waves are mostly between 3.7-4.2 GHz aren't they??

 

[bloomdog]

Preliminary testing produces an 8% improvement in Signal Quality on the Benchmark. :up:up

:

What a great hobby!

Satcom1-- can you give me the different measurements you used? I have the software to create the funnel but I am not sure of the proper dimensions. My waveguide is 65 mm wide.

I have been reading and studying-up on this topic and have even reviewed several patents for feehorns on-line. I am making several different types of feedhorns to experiment with.

 

[satcom1]

True Conical Feedhorn

Satcom1-- can you give me the different measurements you used? I have the software to create the funnel but I am not sure of the proper dimensions. My waveguide is 65 mm wide.

I have been reading and studying-up on this topic and have even reviewed several patents for feehorns on-line. I am making several different types of feedhorns to experiment with.

Bloomdog-

The dimensions for the feedhorn are posted in this thread. The pure conical feedhorn did not work for me. (didn't seem to work for Linuxman) When I added rings then it worked. I also had good performance by just adding an extension to the second and third rings of a flat Scalar ring. That was cut and try but the first extension measures 7/8" deep and the second measures 1 3/4" deep. And for the BSC621-2 produced 8% SQ improvement.

The second method is what I would suggest for you to try. The springy flashing material I used was easy to shape and snapped right on to the Scalar ring.

From what Andrews has done with the Mini-Bud, I feel that a commercially made Concal Scalar ring on a 1 meter or 1.2 meter dish is the best solution.

(Brotherhood) is going to ask his cousin in Japan to ship more to him. I asked him to reserve one for me. That would be the final solution for feedhorn to my way of thinking. ( five weeks miimum wait time )

In the mean time I have started on a 48" Prime Focus Precision dish. Ths dish even though home built should give superior adjacent channel performance to anything manufactured today.

Also, an update on the P*E with offset LNBF findings. I did four or five sat. scans and never went back to check them. I went back last night on some DVB Dream work and found all the scanned channels. I really was amazed at how many C-Band channels I had scanned in with that dish.

With every new replacement satellite launched, there is a chance of stronger signals. But with stronger signals there is the possibility of more adjacent satellite interference. So the almighty "Link Budget" will dictate.

I also noticed that the elevation had to be changed with the sidemount C-Band LNBF. I feel that this has something to do with the P*E dish design. However, I noticed in some of DREAMFOX1 photos that sometimes his LNBF was mounted higher. The new generation of LNBF's will improve things.

I like DREAMFOX1 posting a thread for other dish setups. this will bring forward all the creative stuff others have done. I look forward to seeing your work. it sounds like with an analytical mind good things will come forward. Keep it going.:up

I am dissapointed in how many "Old Timers" with over 30K posts don't get the importance of a mini-bud. There is a great benefit to growth of FTA with the mini-bud. Just because they failed should not discourage others! Guess their egos are bigger then their avatars.

I love "Tinkering" with FTA!

 

[satcom1]

Software Calculations

1. How did you arrive at the values (other than the diameter of the lnbf)?
2. WHy did you use 5.150 GHz? The frequencies of the waves are mostly between 3.7-4.2 GHz aren't they??

There is a software program that you can find on the internet that will do the design for you. You must be a licensed HAM to use this without infringement of copyright. (See Screen Shot) This will do Rectangular and Conical design. If you have difficulty reading the screen shot save and open iin my pictures on you PC you will be able to enlarge it. I also used "Cone Layout V2.0.4"

The program asks you to input frequency, gain and LNBF diameter and calculates aperature diameter and axis length.

Try 4 Ghz. Won't be signficant.

 

[DREAMFOX1]

I changed my lnbf to a BSC421.

Added new updated pics enjoy

 

[satcom1]

BSC421

DREAMFOX1-

Most Excellent! :up:up:up:up

Your setup is a really professional looking.

I'm waiting for your comparison to the Panorama LNBF which was DOA for me twice.

I would guess that the BSC421 will give better performance then the BSC621 LNBF. I just got a BSC321S and it works much better then the price would suggest. I'm very pleased with it and will order more. I took the lower plastic housing off and it fits perfectly into the P*E LNBF arm.

I hope that your success spurs others to emulate your work. I would like comparitive information.

 

[DREAMFOX1]

DREAMFOX1-

Most Excellent! :up:up:up:up

Your setup is a really professional looking.

I'm waiting for your comparison to the Panorama LNBF which was DOA for me twice.

I would guess that the BSC421 will give better performance then the BSC621 LNBF. I just got a BSC321S and it works much better then the price would suggest. I'm very pleased with it and will order more. I took the lower plastic housing off and it fits perfectly into the P*E LNBF arm.

I hope that your success spurs others to emulate your work. I would like comparitive information.

The BSC421 is way better then the Panorama.

Improvement in signal quality 8% increase.

 

[satcom1]

Great Specs.

13K and 65 db gain - Blazing!

Excuse me while I order one.

8% SQ improvement That should set some solid video on your Plazma

 

[DREAMFOX1]

Do you think a 1.2 meter dish will help in getting other transponders?

 

[DREAMFOX1]

13K and 65 db gain - Blazing!

Excuse me while I order one.

8% SQ improvement That should set some solid video on your Plazma

I didnt remember this model having those specs before.
Thats the reason I bought one now.

 

[Mr Tony]

The original 421 (ASC421) has the same specs

 

[bloomdog]

My Progress--1.2M mini BUD and homemade horn

Been studying US patents all weekend to teach myself enough of the scientific background and theory for this project. I am not a great fan of trial and error. There doesn't seem to be very much good scientific/lay literature out there on the subject. I have a Bachelor's degree in physics and studied EM waves, but that was 28 years ago. I have designed and built several protypes of an easy-to-build conical feedhorn to turn my 1.2M into a large BUD
Spent the weekend with my new granddaughter so didn't time to test anything. I will post and photograph all results. Wish me luck!

 

[DREAMFOX1]

I noticed that at night my signal quality is double in strength.

Must be a heat issue caused by heat rising from the roof during the day.

Is there anyway to block the lower part of the dish arm?

and

What material should I use?

 

[satcom1]

I noticed that at night my signal quality is double in strength.

Must be a heat issue caused by heat rising from the roof during the day.

Is there anyway to block the lower part of the dish arm?

and

What material should I use?

The thermals rising between the arm and dish won't have much effect.

The solar radiation would most of the time be too small to notice. During a Solar Flare episode solar flares do effect all communications of e/m.

My guess is that with all the weight you have on the arm, when the arm gets hot it sags.

Just to eliminate that as a possibility, put a tent over your installation, like one of those patio tents that you see blowing around on AFV.

 

[satcom1]

The ART of RF

Been studying US patents all weekend to teach myself enough of the scientific background and theory for this project. I am not a great fan of trial and error. There doesn't seem to be very much good scientific/lay literature out there on the subject. I have a Bachelor's degree in physics and studied EM waves, but that was 28 years ago. I have designed and built several protypes of an easy-to-build conical feedhorn to turn my 1.2M into a large BUD
Spent the weekend with my new granddaughter so didn't time to test anything. I will post and photograph all results. Wish me luck!

Did you ever see a radioman tune a VHF mobile mount antenna? With a wattmeter inline you move your hand closer and then away from the antenna and observe the power. If it goes up you cute a little off. Try again and if no change you've got it tunned. It really is a cut and try method.

You are very dedicated to do this research on the issue. I too have forgotten much of my experience. Sadly, there is hardly anyone going into engineering today. IKE had the right approach by rolling money and people into R&D. We need another JFK to challange society.

I am very much looking forward to your testing. I only wish someone would have come forward to you or Linuxman with a commercially manufactured conical scalar ring.

Well if Brotherhood comes through with my conical feed horn then we will be able to finalize that as a potential improvement.

Yes ,good luck, and thank you for sharing.

 

[satcom1]

`1.2 Meter Dish

Do you think a 1.2 meter dish will help in getting other transponders?

Certainly, that will improve your C-Band performance. You most likely won't see much more improvement on KU.

Just for grins, take a SQ reading on HITN TV 123( 127.5 Offset ). Then put your C-Band LNBF at the center of your dish arm so you are 123 on the LNBF and see what the reading changes to. This will tell us how much offset loss if any you have for the sidemount.

Man, that is so cool that you came up with 8% SQ improvement with this improved BSC421 LNBF.

 

[satcom1]

Hot Dish

DREAMFOX1-

I have measured the dish temperature of a steal dish and a fiberglass dish today.

The fiberglass dish was several shades darker then the steal dish.

The steal dish was 165 degrees and the fiberglass dish was 104 degrees.

i saw on another thread that some steal dishes are being painted white by their manufactures. (Fortec ????)

You might try painting your dish white, to see if your daytime signal improves.

 

[funkypc]

I have been following this thread since it's creation. Very cool.
I suggest the following:
Unless the dish is warping/flexing because of heat, I would paint it Black so it absorbs more heat from the sun.
My theory is that there would be more of a problem with the dish reflecting the suns light/heat toward the LNB and less of a problem with the dish absorbing the heat (and thus not reflecting it toward the LNB).

I agree that setting up a tent would be a great way to block the sun temporarily to see if that changes anything.

 

[brotherhood]

just a heads up,the rings are on there way from Europe satcom1.