My first multiple LNBF setup

[Jason S]

Recently, I ordered some extra parts and with rainy dreary weather for the past few days I got to thinking about a small project to try. I've been researching multiple LNBF setups and thought I'd try it out on one of my 1.2 m dishes.

I didn't make it to the hardware store before they closed on Saturday. They close at 1:00, not open Sunday; orange and blue box stores are a 2 or 3 hour round trip.

I started looking around the shop for something I could use for a bracket. We moved earlier this year and have several of these laying around:


They are hanger bars for wardrobe boxes, the clothes hang on these stamped metal bars inside the moving box.

I couldn't tell you the gauge for sure, but maybe 20? Thicker than flashing and most roofing sheetmetal but can be still be cut with tin snips and aviation shears.

I made some preliminary checks and the hanger bar looked like it might work. I wanted to make it so that I wouldn't have to drill holes into the factory arm.

Inspired by several recent and older posts, a desire for some project using parts on hand and bored being in the house; I did some cutting, bending, painting and riveting and this is what I came up with:



I didn't take photos of the build process. It's not perfect, but it is a pretty stable platform to attach an LNBF.

I took the receiver and TV out to the dish to see what, if anything I could get. I decided to try for 103W and after about 15 minutes I had a signal.

I fiddled around with it for another 45 minutes or so and had the transponders on "the List" at either very good and steady such as the beach cams or decent enough signal to scan and watch.

This is what it looks like from the west side. The center LNBF is on 97W.


Looking from the front of the dish, camera is not level, again 97W on center LNBF and 103W to the right (east).


Looking from the east side of the dish to the west.


This isn't complete yet (I have other uses for my vice grips), but here are my observations:
I believe that the 103W LNBF is looking too far down and it is too far forward. I would think that it would be closer to the level of the 97W LNBF and maybe not forward so much.

I also believe my bracket is too high and also won't allow the LNBF holder to move away from the dish without raising it even higher. I may be able to modify the LNBF bracket some; however, I think that I'm probably going to start with a clean sheet.

 

[primestar31]

I use EMT (electro-metallic tubing, either 1/2 or 3/4 inch) and EMT hangers for multiple lnbs. EMT is cheap at Lowes or Home Depot, cuts easy with a hacksaw and with EMT hangers, can look really professional, and has all sorts of different axis's of adjustment if done right.

 

[KE4EST]

Very nice mod. I like the fact that you used what you had and made it look decent.

 

[cee]

That's a nice setup, I always try to use the center lnb to the weaker SATs or tps like in my case I would use 103 centered and 97 to the side.very nice setup Jason.

 

[Jason S]

I use EMT (electro-metallic tubing, either 1/2 or 3/4 inch) and EMT hangers for multiple lnbs. EMT is cheap at Lowes or Home Depot, cuts easy with a hacksaw and with EMT hangers, can look really professional, and has all sorts of different axis's of adjustment if done right.

I had thoughts about using EMT... Just didn't make it the hardware store in time and didn't want to make the long drive to orange/blue box store... I'm thinking if I rebuild the mount, it'll be from EMT.

 

[Jason S]

Very nice mod. I like the fact that you used what you had and made it look decent.

Thank you. It was fun engineering the mount and then having it actually fit and work.

I'm still wondering about the position of the 103W LNBF, but it's still working where it is.

 

[Jason S]

That's a nice setup, I always try to use the center lnb to the weaker SATs or tps like in my case I would use 103 centered and 97 to the side.very nice setup Jason.

Thank you! Centering on 103 is a good idea: If I have time and suitable weather, I'll have to try 103 on center and 97 off the side.

 

[cee]

Thank you! Centering on 103 is a good idea: If I have time and suitable weather, I'll have to try 103 on center and 97 off the side.

You're welcome Jason don't forget that 103 w Ku skew is off about 26 degrees so peak it as best as possible ,once set then adjust 97 w lnb.good luck and have fun.?

 

[phlatwound]

Here's a great thread to study to get info on multifeed setups.

http://www.satelliteguys.us/xen/thr...-whole-ku-arc-with-fixed-dishes.159936/page-3

 

[Keith Brannen]

This isn't complete yet (I have other uses for my vice grips), but here are my observations:
I believe that the 103W LNBF is looking too far down and it is too far forward. I would think that it would be closer to the level of the 97W LNBF and maybe not forward so much.

I also believe my bracket is too high and also won't allow the LNBF holder to move away from the dish without raising it even higher. I may be able to modify the LNBF bracket some; however, I think that I'm probably going to start with a clean sheet.

I agree with your assessment, the bracket is too high. Therefore, it isn't allowing you to lower the LNBF to the correct position. By angling it forward and on such an angle you are getting it closer to where it should be and are intercepting the beam.

Not knowing your exact location in Kansas, I used Wichita as a location and the difference in elevation between 97 (46.3) and 103 (45.9) is only .4 degrees. Therefore, your 103 LNBF should only be just slightly higher than the 97 LNBF. If you look at the photo aimed at the front of the dish, you can see that the two feedhorns are roughly at the correct height I would expect to see, but to get that position you had to push it forward and angle it down. A new bracket is in order which would allow you to hit that sweet spot.

 

[cee]

Hi Keith I use these types of brackets and holders,it gives you so many different angle positions,height positions and back and forth positions.

 

[Keith Brannen]

Hi Keith I use these types of brackets and holders,it gives you so many different angle positions,height positions and back and forth positions.

I also use those in my system (as well as others, both store bought and homemade). The only thing I found that I didn't like with them was that the straight long bar that is used to mount the LNBs didn't follow the curvature of the dish and which the LNBs (especially those further from the centre) need. Therefore, I usually split the bar so that on each side I could angle the outside ends of the bar in towards the dish a bit. Also usually only put one LNB on each bar for greater control, and for other LNBs on the same side used a different bracket. Other than that, they work fairly well. Also, the LNB holders I have used (with modifications) to attach to some of the flat brackets that I use.

 

[cee]

I also use those in my system (as well as others, both store bought and homemade). The only thing I found that I didn't like with them was that the straight long bar that is used to mount the LNBs didn't follow the curvature of the dish and which the LNBs (especially those further from the centre) need. Therefore, I usually split the bar so that on each side I could angle the outside ends of the bar in towards the dish a bit. Also usually only put one LNB on each bar for greater control, and for other LNBs on the same side used a different bracket. Other than that, they work fairly well. Also, the LNB holders I have used (with modifications) to attach to some of the flat brackets that I use.

I know what you mean, I'll take a picture of my modified 3 c band scalar rings pointed at 99 103 and 107
On Saturday.it looks like a bear chewed it up and spit it out lol it does work OK though lol.

 

[Jason S]

I agree with your assessment, the bracket is too high. Therefore, it isn't allowing you to lower the LNBF to the correct position.

...your 103 LNBF should only be just slightly higher than the 97 LNBF. A new bracket is in order which would allow you to hit that sweet spot.

Thank you for confirming my suspicions. The LNBF just didn't look right and with adjustments it appeared that it wasn't going to be right...

I've re-read the Linuxman post (very, very nice project) and believe I'll have a second go with a better bracket setup; most likely made from tubing.

 

[Keith Brannen]

I look forward to seeing your next bracket and report.

 

[Jason S]

I plan on stopping by the hardware store in a little bit...

 

[danristheman]

Jason look up some up of my threads on my 1.2 meter dish multi lnb setup.

 

[RimaNTSS]

I will trow in some ideas for building multifeeds. Some of them are easy to build form parts bought in Home Depot type shop. Some are custom made and some bought in Sat-shop.

 

[Jason S]

My first multiple LNBF setup, Mark II

First: I appreciate all the suggestions, links and postings. They have all been very inspiring and extremely helpful.

So back to the drawing board and following the suggestions of many postings, I re-engineered and simplified the multiple LNBF bracket. Additionally, I re-engineered the LNBF mount to better suite my new bracket.

For the mount, I used the recommended EMT conduit. To mount the EMT, I modified rafter ties. I had to bend one of the rafter ties the opposite direction and then cut off a bit for the factory dish arm supports to fit, as well as drilling holes in the appropriate places to fit the dish LNBF mount.

New bracket:



Basing my new LNBF mount on others posted here, I used the plastic LNBF portion of the aftermarket holder. However, I modified it to better place the LNBF on the new mount. My mount used a 1 1/2" EMT conduit mount cut in half. Then bent to fit onto a ground clamp for 1/2"-up EMT tubing.

The photo below shows (L to R) the metal portion of the aftermarket LNBF mount, the remaining half of the 1 1/2" EMT conduit mount and the modified conduit mount on the ground clamp.


There is enough gauge in the conduit strap metal to give it rigidity but still allow for 'tweaking' if needed. For some additional left/right movement (azimuth?), the portion of the conduit mount attached to the ground mount clamp screw could be elongated (lower screw as shown in the above photo & left side in photo below). I didn't do that on this particular mount.

Here is a side view of the new LNBF mount clamp.


Since the new LNBF mount had a bit of side to side play, I made a small channel from some more of the clothes hanger box bracket. The channel took up the play but still allowed the plastic portion of the LNBF holder elevation movement.


Modified LNBF mount assembled in the lowest position.


Modified LNBF mount in the highest position.


View from front with modified LNBF holder in highest position.


As I had leave I needed to use up before the end of the year, I took off from work early. I came home and actually got to nap (a rarity when you have 3 children that are 5 years old and under).

At some point previously, I had read on this site about using the plumbers strap to help maintain dish structure. Well, I woke up and thought about adding reinforcement to the stamped dish and actually had some idea where my stash of plumbing strap might be (see above posts about recently moving- I've been using my shop before getting fully unpacked; also see above about 3 children under 5 years...).

So before mounting the new multi-LNBF bracket on the factory arm, I added the plumbers strap and used a 1/4-20 screw to allow for any needed adjustments.


After adding the reinforcement strap, I placed the factory LNBF arm in place and secured the mount arms.

Views of new bracket in place on the dish. Like previously stated, I simplified the setup. The modified rafter ties keep the bracket from moving fore/aft and the strap below the factory LNBF arm keeps the mount tied down to the factory arm.


I then added the newly modified LNBF mount to the new bracket.

At this point, I brought out the TV and receiver and proceeded to tune in 103W again.

It wasn't long and I had a lock again on 103W, then I proceeded to try to peak the LNBF to the various transponders. I was getting a decent signal on the transponders, but not exactly what I thought they should be. I also discovered that if I moved the factory LNBF arm up (ever so slightly), the signal quality would peak.

SO, I tuned to a weak 103W transponder, went to the back of the dish and slowly tightened the 1/4-20 screws on the plumbing strap at the back. As the strap became taught, I watched the receiver and noted that the quality went from bouncing in the 50's to 60's up to a steady 70-72. This is using a Titanium PLL LNBF w/ Manhattan RS-1933 receiver. I turned off the receiver, swapped the RG-6 to the center 97W LNBF and checked signal with an improvement observed there as well.

I swapped back to the 103W LNBF and 'tweaked' some more until I was at a happy compromise on quality for all the transponders.

These photos are of the mount and LNBF bracket with the system pretty well peaked on 103W.


Looking east:


Looking west:


At this point, I probably could do some more to this... However, I'm pleased with the results and it's been fun to fabricate, install and it actually work. I will probably work with this mount some more (hence the additional length on each side) until I can do my planned polar mount.

As stated earlier, I played with this until I got 70's on the transponders. Here is one example with the new setup:

 

[Keith Brannen]

Excellent work, very nice indeed!

Your design has pretty much covered all the possible contingencies necessary for multiple LNBs on a dish (placement, height, adjustable LNB distance from dish, etc.) and allows for slight modifications to the LNB holder/clamp for additional LNBs further out from the centre LNB.

Very well thought out.