Homemade 2 degree monoblocks on Ebay

[schlever]

A guy is selling 'homemade' 2 degree monoblock LNB's on Ebay. I'm sure someone on here would be able to use the pictures to make one themselves. Gotta love the duct tape!

New! 2 Degree Monoblock KU FTA Linear LNB / LNBF - (eBay.ca item 330267335336 end time 11-Sep-08 11:31:41 EDT)

 

[empiretc]

that is funny looking, but hey, if it works. i think i would rather buy a multi-lnbf offset bracket or try building my own instead of paying that much.

 

[Davage]

Cool.. That proves that it can be done. I really want 123/125 on one reflector. I guess I'll have to do a little experimenting. I've got some old linear ExpressVu LNBs (from the 1997 era) that I can afford to mess up.

I wish that Sadoun would get one of the manufacturers of their LNBs to look at a design for 2 degree spacing...

 

[Mr Tony]

but do we know if it works? From the pic I'm skeptical

 

[Morbius]

If you don't like that one there is a $60 one available. WOW!

New! 2 Degree Monoblock KU FTA Linear LNB / LNBF - eBay (item 330266820364 end time Sep-10-08 03:46:26 PDT)

 

[cracklincrotch]

 

[eurosport]

More like...

 

[Mr Tony]

If you don't like that one there is a $60 one available. WOW!

New! 2 Degree Monoblock KU FTA Linear LNB / LNBF - eBay (item 330266820364 end time Sep-10-08 03:46:26 PDT)

its the same thing

 

[Mr Tony]

The reason I say skeptical is in the auction they say 97 & 95...well crap I can get 95 with a 18" dish so you dont think if its off a little bit it wont work? Of course it will

now lets see what happens if you do say 87 & 89 or 83 & 85

 

[empiretc]

I really want 123/125 on one reflector.

me too.. as soon as it's there.

 

[bloomdog]

$10 for shipping. Must be heavy.

 

[cracklincrotch]

So for the price of a six pack you could either get something that does what's claimed or is worth what was paid.

Why don't you go first.

 

[Anole]

roll your own?

Back in 2006, Iceberg got a T-90 toroidal dish, and reviewed it.
In that thread, he and JerryT (and others) conspired to get 2° spacing with regular large LNBs.
Some of the creative ideas they came up with, included belt sanders, grinders and ... more drastic measures.

Somewhere in my travels, I'd seen a solution where one feedhorn was ground down, so I posted it.
That was more to encourage the guys to get physical with their hardware! - :up
Take a look at the pictures, as well as the entire thread, and tell me some grinding on SatAV's little MINI LNBs wouldn't be cheap and smart. -
And at $10 each, you could flub quite a few before spending $60 the eBay guy wants.


The only other thing to consider, is that LNB-spacing is determined by the focal length of the dish.
So, there's no one-solution-fits-all.
But with many using Fortec, SatAV, and 3ABN dishes, that might be one solution. (to be verified)
If you needed 2° on a Primestar 84e for instance, ya might want to verify spacing before going into production.

 

[schlever]

Thanks Anole, that was more what I was thinking when I saw the ad, thats why I posted it ...... with our group of guys, someone here is bound to use it as inspiration

 

[empiretc]

wouldn't it be possible to achieve 2* spaced lnbs using a holder this like one on fleabay?

Item # 220276374784

seems feasible using the bullet style lnbs.

 

[Anole]

The last time I did a calculation for two MINI LNBs on an 84e, they fit about 3° apart.
That was with 'em touching, side by side.
And regardless if one is a little higher than the other, they can't get any closer together than side-by-side.
Without grinding, that is.
edit: that was based on published pictures, not calculations discussed below.

Now, I didn't have an 84e to test on, so I can't say for certain that you wouldn't get some signal.
And maybe enough to make you happy.
Filing them down or grinding a bit off the side of each, should do it, as a last resort.
By all means give it a test drive, if that's what you want!

You'd want to find the proper skew for each LNB before proceeding, too.


If you had a dish with a longer focal length (like a 6 foot Prodelin offset) , then the distance between LNBs is bigger for a given number of degree spacing of the birds.
That's one reason I want to get such a dish, and put a whole rack of skinny LNBs out in front of it.

The larger Channel Master (Primestar) dishes with the three long LNB support arms (maybe only in 1.0m and 1.2m sizes), look to have a long focal length.
There are simple calculations we can do to see what the required spacing for 2° birds would be.
Just need the focal length

I hate to state the obvious, but if the MINI is 1½ inches in diameter (40mm), then the closest center-to-center spacing of two of 'em, would be 1½ inches.
So, if you find that your 2° birds focus closer together than that, then something's gotta give.