Sat-Forum.Net

drspastic wrote: ↑26 Jun 2022, 16:52 hi guys, im new here and fairly new to satellite.
i am setting up 2 2.4m dishes that would have ended up as scrap. partly to use qo100 for radio ham stuff but also to see what i can find up there.
now i have learned that scalar rings need to match the dish size. i have a new c band lnb that has adjustable rings so thats easy.
one of the dishes i want to have ku and c band. im hoping both at prime focus.
many youtube videos, mainly from india and africa involve sawing off the end of the c band lnb and installing the ku band behind it.
any thoughts on this? im sure it might work but is it going to be worse than doing side by side or even closer by cutting into the scalar rings for c band?
i am waiting for my bullseye lnb to arrive. of course it is not designed for a 2.4m dish. i have the original lnbs for both dishes. one is a large heavy flange mount with magnetic polariser then ku scalar ring feed. all seperate. the other is much smaller with switchable polarisation and circular flange and scalar ring feed. both are dro.

so is there an advised way to get one of the ku band scalar rings on the bullseye?
what would the old hands recomend i do re c and ku on one dish while retaining full signal from the whole 2.4m reflector?
should i just use the one dish for c band and my 2.4ghz uplink, and the other for an array of older lnbs (motor is busted)

i hope my first post on this forum doesnt ruffle feathers, and please tell me if im posting in the wrong place.
my next post will be rather technical so i will wait answers to this one first

many thanks

drspastic wrote: ↑26 Jun 2022, 18:58 thanks for the reply. my dishes are all prime focus, and i have the scalar rings from the old lnbs. they are flange mount though.
i think the 2nd photo would be rather inefficient because the conical scalar rings that are part of the lnb are in the shadow of the 2.4ghz patch antenna.
for my uplink i will be making a helical antenna as many users report much higher gain (i hate that word in this context).

i suppose i need to find a good book on microwave engineering so i can understand the relevent positioning of lnb, focal point, scalar rings, position of dipole etc. im pretty good with optics and radio but this black art is more like plumbing