Can an Invacom LNB be Modified to work on a Big Dish with an old Chaparal FeedHorn?

[jsattv]

I currently have a 1 Meter Fortec Star Dish on my Roof with a HH120 Stab Motor and an Invacom QPH-031 LNB. I have had severe wind damage at least 5 times in the last 6 months having to constantly climb the ladder to realign everything with a small TV and a Satellite Receiver.

I am now setting up a 12 Foot Mesh Dish in my backyard on a heavy duty steel tripod. The 2nd hand setup came with a Uniden 9900 Receiver and 9900 P Power Supply. The old LNB it came with was a Chaparal Feedhorn with an attached Tee-Comm 5000 LNB. The Scalar Ring for this Chaparal Feedhorn is 6.5 inches in diameter which is about 1/3 inch too wide to fit a BSC-621-2 LNB. It will likely fit a Corotor II FeedHorn.

My question is:
If I remove the 1 Meter Fortec Star Dish from the Roof can I reuse and somehow modify my existing Invacom LNB for use with my old Chaparal Feedhorn on my 12 foot Mesh Dish? I tried to upload a picture of my old Chaparal FeedHorn but it says my 189 kb pic exceeds the limits of this Forum. Any reply / suggestions re what type of LNB to use or how to modify my Invacom LNB for use on my 12 Foot Mesh Dish would be very much appreciated.

[rainman]

Originally Posted by jsattv

I currently have a 1 Meter Fortec Star Dish on my Roof with a HH120 Stab Motor and an Invacom QPH-031 LNB. I have had severe wind damage at least 5 times in the last 6 months having to constantly climb the ladder to realign everything with a small TV and a Satellite Receiver.

I am now setting up a 12 Foot Mesh Dish in my backyard on a heavy duty steel tripod. The 2nd hand setup came with a Uniden 9900 Receiver and 9900 P Power Supply. The old LNB it came with was a Chaparal Feedhorn with an attached Tee-Comm 5000 LNB. The Scalar Ring for this Chaparal Feedhorn is 6.5 inches in diameter which is about 1/3 inch too wide to fit a BSC-621-2 LNB. It will likely fit a Corotor II FeedHorn.

My question is:
If I remove the 1 Meter Fortec Star Dish from the Roof can I reuse and somehow modify my existing Invacom LNB for use with my old Chaparal Feedhorn on my 12 foot Mesh Dish? I tried to upload a picture of my old Chaparal FeedHorn but it says my 189 kb pic exceeds the limits of this Forum. Any reply / suggestions re what type of LNB to use or how to modify my Invacom LNB for use on my 12 Foot Mesh Dish would be very much appreciated.

the invacom is made to be used on a off set dish the performance won't be as good on the 12 footer if you are wanting circular signals on the 12 footer they make a scalar ring with a circular lnb built in then you could use. then add a co rotor II with a couple of norsat lnb's and have the best of all worlds.

[jsattv]

Thanks very much for your reply Rainman. Being new to this great hobby I'm not sure I understand your answer. Are you saying that I would need to purchase 2 separate Feedhorns - one for Circular and the Corotor II for C & KU Band Satellites, then swap out each one as needed??

[rainman]

Originally Posted by jsattv

Thanks very much for your reply Rainman. Being new to this great hobby I'm not sure I understand your answer. Are you saying that I would need to purchase 2 separate Feedhorns - one for Circular and the Corotor II for C & KU Band Satellites, then swap out each one as needed??

no the co rotor II will fit in the scalar ring that the circular lnb is installed in.see picture.

[jsattv]

Thanks a lot Rainman great info, guess the only thing that I need to know is will that Circular FeedHorn Fit my existing Scalar Ring (which is 6.5 inches inside diameter). My 6.5 inch Scalar Ring attaches to the 4 dish poles and currently clamps over an existing older Chaparal FeedHorn with a Tee-Com LNB attached to it? I had thought that my Scalar Ring would only just fit the Corotor II, so I guess I need to know the diameter of that Circular Feedhorn to get the best of both worlds as you mentioned.

[rainman]

Originally Posted by jsattv

Thanks a lot Rainman great info, guess the only thing that I need to know is will that Circular FeedHorn Fit my existing Scalar Ring (which is 6.5 inches inside diameter). My 6.5 inch Scalar Ring attaches to the 4 dish poles and currently clamps over an existing older Chaparal FeedHorn with a Tee-Com LNB attached to it? I had thought that my Scalar Ring would only just fit the Corotor II, so I guess I need to know the diameter of that Circular Feedhorn to get the best of both worlds as you mentioned.

the circular feed horn as you are calling it is the scalar ring remove the one on your dish install the new one in the picture above and install the co rotor II into the center. then you will have a nice neat package to receive C,KU, and circular signal.

[1captain]

Originally Posted by rainman

the invacom is made to be used on a off set dish the performance won't be as good on the 12 footer if you are wanting circular signals on the 12 footer they make a scalar ring with a circular lnb built in then you could use. then add a co rotor II with a couple of norsat lnb's and have the best of all worlds.

Hi Rainman I would beg to differ with you on saying that a offset feed lnb isnt going to work on a prime focas dish. Reason why is that i added 1 to mine about 7 or 8 years ago, (wich was a soney dbs lnb) and about 3 years ago added a fortec universal on the other side of the C&Ku feed, but what i did is alot different than the picture that u posted, i drilled an cut the scalar ring (used channel master fer the 3 set bolts to hold feed throat) and mounted lnb right next tp the c&ku feed, then welded a angle bracket to the scalar ring and atached the lnb with a hose clamp to it . And it works very well on a 10ft micro-dine glass dish, also have a 1 meter dish(offset feed ku only channel master) with a motor on it and if i find a week feed with it / i will use the 10 ft. dish and just about all the time the 10ft will be a lot more than quality of the 1meter dish. Now i can see youre point if he is dealing with a old 12footer with very large holes in the mess but in my case my dish was commercal and used fer uplinks and i am very happy with it and would recomened any one who wants to try it that it works, just wanted to give feed back what i done and how it works. Captain

[rainman]

Originally Posted by 1captain

Hi Rainman I would beg to differ with you on saying that a offset feed lnb isnt going to work on a prime focas dish. Reason why is that i added 1 to mine about 7 or 8 years ago, (wich was a soney dbs lnb) and about 3 years ago added a fortec universal on the other side of the C&Ku feed, but what i did is alot different than the picture that u posted, i drilled an cut the scalar ring (used channel master fer the 3 set bolts to hold feed throat) and mounted lnb right next tp the c&ku feed, then welded a angle bracket to the scalar ring and atached the lnb with a hose clamp to it . And it works very well on a 10ft micro-dine glass dish, also have a 1 meter dish(offset feed ku only channel master) with a motor on it and if i find a week feed with it / i will use the 10 ft. dish and just about all the time the 10ft will be a lot more than quality of the 1meter dish. Now i can see youre point if he is dealing with a old 12footer with very large holes in the mess but in my case my dish was commercal and used fer uplinks and i am very happy with it and would recomened any one who wants to try it that it works, just wanted to give feed back what i done and how it works. Captain

as I stated captain it will work but the performance may be in question as the focal lenths of a prime focus dish and a off set dish is different. by no means did I mean to imply that it wouldn't work. the longer you are in this hobbie someone will figure out away to make just about anything work.

[1captain]

Yes i know Rainman beed doing this line of work(satellites) since 1980 and have seen lots of change. Captain

[rainman]

yep been thinking of trying this modification with a old Direct Tv single LNB I have and one of my old scalar rings and see what happens.I believe if I can get the cover off all I will need to do is drill a hole in the scalar and glue the lnb in place.

[1captain]

Originally Posted by rainman

yep been thinking of trying this modification with a old Direct Tv single LNB I have and one of my old scalar rings and see what happens.I believe if I can get the cover off all I will need to do is drill a hole in the scalar and glue the lnb in place.

Rainman will let you know how i did mine. when i first did it with dbs lnb just drilled a hole in the scalar ring about 1inch from the feed throat then took a saw and cut a notch from the inside (where youre c&ku goes)to the hole i drilled then welded peice of aluminum to the scalar and bent in a L to use as something to hold lnb at first used a nut an bolt, like what is used on the birdview lnb converson, hose clamp works better. now since then about 3 years ago when i added the fotec i redid another scalar, now fer 2 lnbs, up their i took a straight edge put a enclometer on it and set it to my lat. then marked a line tru center of scalar ring that is where i drille 2 holes on each side of feed throat, then recut an welded like i did before, both of my lnbs are righ next & touching the c&ku troat. that is the secret cause tryed mounting off to the side before but as close to center will perform the best from my testing. and remove plastic covers that are on dbs-lnb, now i have a CE-1000 in place of the soney dbs lot easyer mounting, and beter quailty. hope all helps you out, cause i have hours in doing all that. and if you do a lenair lnb had to mount mine to the right of the C&ku fer skew of the lnb. so hope all hepls Captain

[rainman]

Thanks for the info Captain will be a future project when we get the time probaly this winter when we can't do anything outside.

[wejones]

Originally Posted by rainman

yep been thinking of trying this modification with a old Direct Tv single LNB I have and one of my old scalar rings and see what happens.I believe if I can get the cover off all I will need to do is drill a hole in the scalar and glue the lnb in place.

I'm not sure that it will do any good to take the cover off. It does reduce the size of the throat from 28mm to 23mm, however it's all one piece, and there is no way to separate the front scalar ring section from the throat or from the back LNB section. So there is really no way to get it in a hole in the scalar ring, unless you can split the scalar ring into two halves somehow.... not worth the effort.

I took the cover off one of mine just out of curiosity.

When I put one of these (actually the same one I just took apart) onto my 10' dish, I just strapped it on the side of my Corotor II. It did work, but not well. Actually got better quality out of an 18" dish. It probably would have been better if it was closer to the focal point, like with these scalar rings with holes, but that only get's you a couple inches closer to the focal point. Off to the side, where I had it, I think it was about 9 or 10 degrees off. The way I did it though, had the problem that I couldn't move it in/out to get closer or further from the dish. If I was doing it again, I think I'd mount an old lnbf holder there, and use that to allow adjustment.

I eventually took the thing off though, because I got MUCH better results using the QPH-031 on my 90 cm Fortec.

But efficiency wise, these little LNBFs are made for an F/D of about 70, not the 30-40 typical of big dishes. So it would effectively only be seeing about half the dish, even if at the focus.

[jsattv]

Originally Posted by rainman

the circular feed horn as you are calling it is the scalar ring remove the one on your dish install the new one in the picture above and install the co rotor II into the center. then you will have a nice neat package to receive C,KU, and circular signal.

Thanks a lot rainman. I can order the Corotor II locally, but need to get C and KU LNB's for it. I guess the Norsats - 8515 for C Band, and 4506A for KU Band are the recommended ones? The local dealer was offering Precision / Astrotel - PMJ LMJC - LNB for C Band, and Precision PMJ LMBKU for KU Band for approx $60.00 each. Anyone tried these units?

Also re that Circular FeedHorn and LNB in your picture - any idea where to get one and its cost?? Does Sadoun sell it? Or do I need to do a search on ebay?

[rainman]

Originally Posted by jsattv

Thanks a lot rainman. I can order the Corotor II locally, but need to get C and KU LNB's for it. I guess the Norsats - 8515 for C Band, and 4506A for KU Band are the recommended ones? The local dealer was offering Precision / Astrotel - PMJ LMJC - LNB for C Band, and Precision PMJ LMBKU for KU Band for approx $60.00 each. Anyone tried these units?

Also re that Circular FeedHorn and LNB in your picture - any idea where to get one and its cost?? Does Sadoun sell it? Or do I need to do a search on ebay?

I have used the Astrotel on ku before believe me you want to go with the norsats.