Minibud lnb problem

etlam34

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SatelliteGuys Family
Mar 3, 2017
92
94
Quebec city
Every time it rains my c band lnb on my 4ft geosatpro fills up with water. Last time, i swapped for another c band lnb while the wet one dried up in the shed. This time, the back up lnb had smudge inside, so i cleaned it up with a hand towel and a tooth brush. I even used my wife’s hair dryer, in both lnbs. The dmsi model ended up working but i think the smart sat model died. The main problem is that V polarity end up not working after a rain storm while H polarity still works. The conical scalar ring and the lnb angle doesn’t help. My 4ft prime focus dish doesn’t have that problem. I’ll attach a picture to this post to help understanding the water collecting problem. Thanks for your inputs!
 

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Brct203

SatelliteGuys Pro
Dec 24, 2016
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Connecticut
Every time it rains my c band lnb on my 4ft geosatpro fills up with water. Last time, i swapped for another c band lnb while the wet one dried up in the shed. This time, the back up lnb had smudge inside, so i cleaned it up with a hand towel and a tooth brush. I even used my wife’s hair dryer, in both lnbs. The dmsi model ended up working but i think the smart sat model died. The main problem is that V polarity end up not working after a rain storm while H polarity still works. The conical scalar ring and the lnb angle doesn’t help. My 4ft prime focus dish doesn’t have that problem. I’ll attach a picture to this post to help understanding the water collecting problem. Thanks for your inputs!
well, yes, that's typical of offset dishes at higher latitudes and anywhere when pointing at low elevation satellites. i read somewhere of someone drilling a small drainage hole in the bottom part of the c-Band waveguide. This said, i'd think that an LNBF cap with only one hole (mounted os that the hole is near the top) or no hole at all, should resolve this problem. I have a 2-year old Titanium LNBF and i think it has multiple holes and would get small amounts of water during storms when it was on my mini-bud. I also have a brand new Titanium C2-PLL, and the cover is solid, no holes. So that would probably be your best solution.
 

Magic Static

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Large plastic tubs like margarine comes in have plastic lids that will fit tightly over the conical scalar. Doesn't block the signal and keeps the water out. :)
 
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etlam34

Thread Starter
SatelliteGuys Family
Mar 3, 2017
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Quebec city
I’ll try the margarine lid! I’ve tried swapping caps between lnbs and it didn’t work out. Maybe i could put the titanium lnb on the geosatpro and the holed cap on the prime focus dish.
 

Magic Static

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Grab a measuring tape and run down to the grocery store and make people wonder as they see you measuring margarine and other products. LOL
 
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RimaNTSS

SatelliteGuys Pro
Aug 9, 2013
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Riga
First of all, it is necessary to drill drainage hole in the body of the LNB (as an example, on attached picture I circled yellow) DrinageHoles.jpg . Secondly, I personally think that usual LNB with conical feedhorn is not the best solution to be used on an offset dish. Look for something like this, where dielectric feedhorn is inside the cylindrical plastic cover. ScreenHunter_878 May. 13 15.58.jpg
 

Corrado

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Apr 2, 2007
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Hudson Valley Region, NY
I started covering the entire LNBF and conical scalars with heavy plastic bags. Since the the prime focus design feed horns are designed to point down, not up as I have them on my 3 Prodelin offset dishes. I gave up trying to keep various caps over the scalars, the water was still getting in over time despite my best efforts.
 

Cham

VE4GLS
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Dec 19, 2008
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I use heavy gauge plastic vapour barrier for mine. Found the plastic margarine container lids crack and leak after a couple of months. Might have to do with the cold in the winter or high UV levels up north here.
 

Titanium

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May 23, 2013
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Be sure to rotate the skew to place the horizontal/vertical probes pass-throughs on the top of the feed housing and not on the bottom where water build-up might stream or leak into the electronics cavity.

If mounted on a fixed dish, after optimizing the skew, drill a hole through the bottom or ear of the feedhorn cavity at the 6 o'clock position. This will allow collected water (remember also the condensation) to drain out of the cavity. Check the drain occasionally as even a small amount of pooled water will negatively affect the signals inside the feed.
 

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