The DirecTV SL3K4NR1-03

[Trust]

It crossed my mind , i've seen "plastic" feedhorns in several lnb's (smart) . Dont know they perform as good as alu .
Since i did not know such a company in the neighbourhood and could not imagin they could make such small ended tubes , i let it down .

 

[Vipersan]

I dont doubt that certain plastics with the correct dielectric properties would work to some degree..
Like you I've seen such feeds in use ..In Ku at least
There is one in a sort of polythene hidden in the cone of a bullet shaped ALPS lnb..
But as to efficiency ..particularly in Ka ..I have reservations.
We are after all dxing and need maximum signal capture ..so ..
imo the feed should indded be metal ...for our purposes at least..
In mass produced units for non fringe applications ..
Plastic may well suffice...
rgds
VS

 

[battenfan]

There are some options. Painting the plastic using conductive ink, include aluminum (alumide?) or carbon particles in the plastic to be printed to make it a bit conductive or 3d print a clay mold and inject metal. Brass, steel, silver and gold are some of the available choices. Shapeways lets you upload a drawing and it gives you an estimate of how much it will cost. I don't know enough about 3d printing to tell if it's hard or even possible to make a long and hollow object like a feedhorn. (Here is a printed antenna)

 

[Trust]

Here a pic of the Apls feed and the front cover of a lnb with a smooth funnel .

 

[Analoguesat]

Ive got access to a 3D printer at work in our technologies dept. If someone can point me in the direction of a suitable STL file for a KA waveguide I'll get one of the lads to knock a test one up (assuming it fits in the printer - it isnt a very big one!) I can send it to VS or Llew for testing as I dont have any KA band lnbs here. (Yet)

 

[Trust]

Just came home with 20 feedhorns , they are beatyfull , more smooth than my own ones .
Tomorrow they will be send .
I suggest we call them in our discussions , KTK2 horn .
I have a bucket full of KU feedhorns , cut from Inverto single BU's
The Ka feedhorn fits exactly in that leftover , with a minor preparation at the lathe they have the same openings angle .
Tests on my Fibo in front of the subreflector shows after focus and elevation adjustments , a increase from 15.4 (KTK2) to 15.6 (KTK2 + leftover)
Not spectacular , but maybe there is more to get at regular offset dishes .
Who wants to test it ?

 

[John]

.... they look beautiful Trust and thanks again for your work.
Can you send a few "leftovers" along with the KTK2's when you send them over to Chris (Scopus) ..... i would like to try the combination out please.

 

[Trust]

I will , 2 for each

 

[Vipersan]

They do indeed look beautiful ..
Looking forward to an improvement in my health ..and the weather so I can ' play out ' with my dishes ..
Thanks again buddy ..
Even those leftovers look interesting..for experimentation..
;)

 

[scopus]

Wow, they look great trust. many thanks for youe hard work! I will also have the leftovers please. Look forward to receiving them, as soon as I do I will post them on gents.

 

[Llew]

I like the look of those babies Trust

Thanks for the update, can't wait to try one.

 

[lovelyperson]

Trust 1........great work and all those you have helped.........good result special thread.

 

[Analoguesat]

Ive been following this thread with much interest - not commenting much as I didnt have anything much to add to the discussion.

But I have to say those KTK2 feedhorns are a work of art, and I hope everyone has great fun testing them whatever the final results. Now I await all your test findings with great interest

 

[Trust]

Package on the run , TrackTrace 3SKABA0478767

 

[scopus]

Feedhorns arrived safely this morning. I must say they are superbly engineered, better that the original Triax I think.
I will be posting these on tomorrow Gents.
Thanks again Trust, brilliant job all round!

 

[Llew]

Thanks scopus, look forward to receiving them.

 

[Analoguesat]

Great stuff - I await your assorted results with much interest

 

[Archive-8]

I chopped up 2 rt Ka-band lnb's on mine.

View attachment 74474

 

[uhf-satcom.com]

That's a good idea for a mod to the US LNB's. I have one of those types, but ended up bandsawing it in half to use the two front end LNA stages. What did you do with the old Inverto LNB's whose feed horns you chopped off?

 

[Archive-8]

That's a good idea for a mod to the US LNB's. I have one of those types, but ended up bandsawing it in half to use the two front end LNA stages. What did you do with the old Inverto LNB's whose feed horns you chopped off?

At the moment they are in the shed.