Homemade c/ku lnbf

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truckracer

truckracer

Thread Starter
SatelliteGuys Pro
Sep 17, 2004
4,338
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Charleston wv
Hey guys, I want to tell everyone about my latest backyard achievement.
I made a homemade c/ku lnbf combo that works great.

I started off with an Astrotel 20 degree c-band prime focus lnbf and a DMS international bullet style .6 KU offset lnbf.

I removed the plastic cover and feedhorn cap from the dms KU lnbf. I held the ku lnbf's feedhorn up to the back of the c-band lnbf and noticed that the diameters of the c-band feedhorn and outer KU band lnbf's feedhorn was near the same diameter. I used a dremel and cut off the outermost two rings from the KU lnbf. I did this for the sole purpose of making it fit.

From an engineering point of view I have no idea what this did for the f/d, gain, or cross-pol isolation.

I used a holesaw and cut out the back of the c-band lnbf. I used a protractor and found the center of the bore. I used a grinding stone and smoothed the edges so the remains of the trimmed KU band feedhorn fit tightly in the hole in the rear of the c-band lnbf.

I carefully lined up the vertical and horizontal probes between the two lnbf's.
this is to preserve skew and polarity fine tuning. You can do this by just looking down the c-band lnbf's feedhorn.

to secure everything, I used some metal epoxy from the hardware store or some folks call it "liquid steel". I let it cure and installed it on the dish.

On my 8.5 foot sami mesh bud, I tuned in G-10R KU band. I started with that pathetic 11718V transponder that is soooo weak. On my 90 cm patriot offset dish i only get 45% signal quality on a nice day with my pansat 2500.

On the big dish I have 90% !!!! I thought I would never see the tube come in so strong.

c-band reception seems unaffected. Percentages on all sats are the same for c-band. KU reception is so much stronger on the big mesh dish than the 90 cm patriot.

I know the KU lnbf is for an offset dish, but the only difference I could see in the internal design of the feed is the scalar rings being enlongated in a telescopic pattern where as the prime focus designs are always flat rings.

This works great, I wanted everyone to know so some of you can make your own. I do not have a digital camera yet, or I would post some pics.
 
Shawn95GT

Shawn95GT

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Supporting Founder
Feb 9, 2005
2,278
1
Phoenix, AZ
That's cool. Another user here tried the Very same with an ASC421 and an offset Ku LNB. I think in his case his signal went down for both C and Ku. His was an offset dish though. I'm glad it worked for you!

Since I have the C/Ku feedhorn / rotor I went ahead and ordered a pair of Norsats for it. I'm sure your setup was MUCH more cost effective :).
 
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