Thread: Mad Scientist strikes again! Poor Man's DISH500+/1000+

Finish my effort to get 118' W. just a few minutes ago. Worked on it for several hours today. Ended up getting a signal strength of 72 from AMC 16.
I first took a bad Dish Network lnb apart to see if I could put the guts of my linear lnb in it. Wouldn't work the linear lnb antenna is in the feed horn and Dish's isn't. Since I had both lnb's apart I decided to take the cover of the linear lnb's feed horn to see what it looked like inside. I was surprised to see grooves already cut inside the feed horn at 45' angle. I took what looks like a piece of circuit board, from a do it your self stereo RCA jacks install and cut to fit in the feed horn grooves (which is not quit 1 and a half inches deep). Aimed my dish with a circular lnb at 119' and swapped lnb's and peaked it.

Duane any pictures?

I had a guy give me his old Primestar dish, so I took the 105 FSS LNB from my SD and did the mod, using Pepper's photos as a reference. But it never really said in anything I read how *deep* the dielectric piece should be. I had a small blank circuit board with no copper about 1.5 inches long that I cut to fit inside the PS feedhorn, at slightly less than the 45 degree notches to really be lined up with the LNB with its skew. But no signal for me...

So tell me, to satisfy my old radio theory classes, is the feedhorn really a section of waveguide? How does the dielectric make the polarity circular, and does it need to be the entire length of the tube?

I really have no need for the 118 signal; this is just climbing the mountain because it's there.

Originally Posted by sigmtr

But it never really said in anything I read how *deep* the dielectric piece should be.

I didn't actually measure it, just described where I found it. The thing has quit working (these SD FSS seem really sensitive to heat this year or what?) so I'll pull it apart and maybe take some more pictures of the parts. [Edit: nope, it wasn't dead, the yard guy must have bumped the dish, I've got it working again]

Originally Posted by sigmtr

So tell me, to satisfy my old radio theory classes, is the feedhorn really a section of waveguide? How does the dielectric make the polarity circular, and does it need to be the entire length of the tube?

I too have been wondering how it actually works. I can't visualize what a piece of plastic does to an RF signal.

Just for kicks I modded a EA 1700KU. It works just fine for 118.7 but it's all internationals on my dish 6000. I'll call dish and see if I can get a freebe trial on something.

Ducktape again ? Under sun it will tear down in one month.

Originally Posted by Smith, P.

Ducktape again ? Under sun it will tear down in one month.

In a month it'll be raining for 6 months again. Ducktape, good stuff. It got apollo 13 back home.

"Duct" tape does degrade over time. Now aluminum tape is used on ducting. It lasts longer and is stronger.

I was wondering if it's possible to convert a Universtal Linear LNBF to cicular and make it pick up both 119k and 119W. The "High Band" of the LNBF receives at 11.7GHz - 12.75GHz. This is perfect for receiver these two satellites.