C Band on Ku Dish

[spongella]

Am trying out this old Channel Master 44 x 40 inch dish on C band, looks like it was originally used in the Ku band. For now have jury-rigged a Titanium C band LNB, but was wondering if anyone has a better idea on how to mount it. The dilemma is, do I have the right focal distance and angle for the LNB? I tried to mimic the correct LNB mounting angle by eyeballing the angle of the Ku LNB bracket. I left that Ku bracket (the lower half that is) attached because it's needed to hold the LNB arms together.

So far have used a Channel Master satellite meter to optimize the signal, and got two channels on 55.5 W: Bolivision with 39% SQ and Meier Norte SD at 36% SQ with some signal freeze.

This is a beautiful dish to work with, fiberglass with heavy-duty mount. And made in the USA!

Thanks for reading.

 

[Magic Static]

Because of the focal point of the dish the LNBF will need to sit as if it were in the original LNBF holder. This of course doesn't leave room for the scalar and thus demonstrates the difficulty in getting good signal. I would reconfigure the LNBF side support arms to allow for positioning of the scalar.
Look at this arrangement http://www.satelliteguys.us/xen/threads/project-butter-on-a-hot-potato.350038/#post-3668556

 

[RimaNTSS]

spongella Antenna's focus (green dot) is located in one place, but LNB's Focal Point (red) in completely another place. Task is easy- place LNB in such way that it's Focal Point placed in Antenna's Focus and you will be able to receive C-band on this nice Channel master 1,2m dish. I would say, if you really wish to do all mechanical work properly- make new feedarms.

 

[KE4EST]

As the others have said you are gonna have to bring your LNBF down to the optimum focal point of the dish, for best performance.
You will have to get creative with those arms.

 

[Titanium]

Great drawing RimaNTSS. Explains the placement very well. I first try and place the center of the new feedhorn opening at the same height and distance from reflector as the original. Then add the scalar and optimize the fore/aft placement to optimize the Signal Quality.

Frankly, I am very surprised that any channel was received with the feedhorn so far away from the sweet spot.

 

[RimaNTSS]

I am very surprised that any channel was received with the feedhorn so far away from the sweet spot.

Of course, reception is possible wherever LNB is located (at a reasonable distance from a "G-spot" ) but that will be multifeed position. And as we all know, LNB in multifeed position works worse than in focus. So, place LNB in focus and you will get better reception.

 

[RimaNTSS]

Even with original CM120 feedarms but self-made LNB holder is possible to install C-band LNB with it's Phace Center in the antenna's Focal Point. I have this holder for Ku-band LNB, but you can see that it will allow lower position of LNBfor approximately 1cm, exactly what we need. One day I will have C-band LNB installed on my CM120.

 

[pacificrim]

An easy way is to perfectly peak it on KU, then remove the KU LNB. Hook up your meter to the Cband LNB and wave it slowly around to find a signal. When you get a good signal, look at the position and then you can figure out how to make the mount.

 

[RimaNTSS]

Inspired by this conversation, just changed 40mm LNB holder to 65mm one, which is designed for 65mm LNB (usually C-band ) , but with special adapter it is also OK for 40mm LNB (Ku-band) . So, now it is only matter of time till I get C-band LNB installed and start to scan C-band signals.

 

[spongella]

Well I am in the presence of greatness, duly represented by all of you on this forum. Lots of great ideas presented by all, and a hearty thanks. Will remove the old Ku holder and see what I can do with the C band LNB. Not in any rush, want to get it right. Will be satisfied to get a few stations from the Eastern arc such as 40.5W, 55.5W, 58W. Maybe some Western arc sats like the old Satmex 5 and 6.

I don't think this setup can be motorized though, not without some major metalwork.For now stationary is fine.

Thank you all for your useful suggestions.

 

[RimaNTSS]

Installed C-band LNB and scanned 5*W, about 80 services came in with decent signal level. "GABON TV" on the screenshot .

 

[spongella]

I see you do not use a scalar ring for C band. No need for one at your location? What size is your dish?

 

[spongella]

Improved holder, will try this in the meantime. Definitely need to get the old LNB holder out of the way. RimaNTSS you have a nice bracket, that 's my goal. Have dual C/Ku for now, just so much easier aiming at Ku first.

 

[RimaNTSS]

I see you do not use a scalar ring for C band. No need for one at your location? What size is your dish?

According to company adjusted this LNB, it does not need scalar rings as they are already inside of this white cover as well as polarization pins.

My dish is Channel Master 1,2m (Made in USA, you know )

 

[danristheman]

Sponge check out my pics I had to make my own bracket look up butter on a hot potato.

 

[spongella]

Very interesting bracket danristheman. I zoomed in on those photos, looks like most of your LNBs with the exception of the center one are attached to a piece of PVC pipe, but can't tell how the PVC is attached to the LNB arms except for wire ties, is that correct? Also, what are those LNB holders, are they plumbing pipe hangers?

Beautiful bracket and very inspiring. Have to work on something like that.

What's the Crock Spread lids about? Keeping rain and snow out of the scalar rings?

I like the logo on the dish.

You are a skilled individual, the bracket is work of art, thank you.

 

[Corrado]

I like Dan's idea with the lids to keep the elements out of the scalars. I wish someone would design sealed C Band LNBFs like the Ku models. On my 3 Prodelins, I have them covered with plastic bags since they face upwards when used on offset dishes.

 

[PopcornNMore]

Makes me want to do some experimenting over the Memorial Day weekend. I've had very good results using my 120cm dish for C-band. Galaxy 16 seemed to come in the best, but that was a few years ago.

 

[danristheman]

Here is another pic sponge. Thank you sponge on your last post. The bracket I made out of left over parts that I had in the jar with nuts and bolts. The c band lnbf in the middle is held up by a upside down bracket from my 1 meter commercial dish that fits into the lower lnb support arm. I use pipe hangers from true value 1/2 '' for ku and 2 to 3 inch for c band. The pvc pipe is held on by zip ties 3 foot pvc pipe 1 foot from actual size of dish 4 foot dish ,3 foot pipe. Double to triple zip ties threaded rods also used. Fake dtv logo to fool management it worked. Lids keep out water and bugs. Thank you again sponge.

I used to play legos when I was a boy build crap out of nothing making aircraft carriers using micro machines as planes on the carrier.

 

[spongella]

Thanks for the picture danristheman. OK I can see from that picture that the C band LNB to the right is held steady with two hangers, good idea due to the size. Never thought to use zip ties to fasten the PVC pipe, what a great idea.

Looks like you had a talent early on in life for building things.