twin output lnb schematic

[deldadeh]

Hi all
i want to know how twin output LNB works? also i need it's schematic!
i searched it over internet but no results i got.
please help me i need to know how do they work!
thanks

 

[ralphmagno]

hello, a twin lnb is like a single and multiswitch in one.
it has 2 lo inside ,one runs at 9.750 ghz and the other runs at 10.6 ghz.
as the signal comes from the satellite there is a horz and vert pol . the signal is amplifies and then the lo signal is injected.
it then passes through a band pass filter and amplified several times again.
the frequency is from 10.700 ghz to 11.700ghz lower band and 11.701 to 12.700 ghz.upper band.
each output is independent of each other.
the satellite receiver sends out a dc voltage and a tone.
14 v dc vert
18 v dc horz
14 v dc +22 khz vert upper band
18 v dc +22 khz horz upper band.

if your lnb is broke the chances you can repair it is very slim.
its best to buy a new one.
ralph

 

[Terryl]

You are also going to need a spectrum analyzer good out to 14 GHz, a high range frequency counter also good out to 14 GHz (or beyond to look for harmonic's), several good low noise high frequency RF generator's (same spec's) and a good assortment of sub miniature caps, inductors, resistors and mosfet IC's, and a little bit of training to get one to work right with out letting the smoke* out of it.


*Note:

To all of you that don't know this, smoke makes electrical and electronic things work, if you let the smoke out of your TV set or toaster it will quit working, this can be tested by dropping a handful of change into it and giving it a bit of a shake (highly not recommended for anyone to try except the criminally insane) it will then start smoking and will quit working.

It is very hard to put the smoke back in once let out.

 

[ralphmagno]

hello,
this guy never said he wanted to modify a 12 ghz lnb to 14 ghz.
forget it it will never happen.
first stage stage amp probably need to be changed because it will not pass 14 ghz.
lo needs to be moved from 10.6 ghz to 12 ghz.band pass filter needs to be modified.
we are talking about a smaller resant cerimac chip and redesigning the lnb
unless this guy has $50,000 worth of equipment to do so it will never happen.
they probably sell the lnb he is looking for.
what does he want to receive at that frequency????
ralph

 

[rolfw]

To all of you that don't know this, smoke makes electrical and electronic things work, if you let the smoke out of your TV set or toaster it will quit working, this can be tested by dropping a handful of change into it and giving it a bit of a shake (highly not recommended for anyone to try except the criminally insane) it will then start smoking and will quit working.

It is very hard to put the smoke back in once let out.

LOL, didn't realise how important the smoke was until my old Philips 28" TV accidentally released its smoke one morning and never worked again.

 

[Terryl]

hello,
this guy never said he wanted to modify a 12 ghz lnb to 14 ghz.
forget it it will never happen.
first stage stage amp probably need to be changed because it will not pass 14 ghz.
lo needs to be moved from 10.6 ghz to 12 ghz.band pass filter needs to be modified.
we are talking about a smaller resant cerimac chip and redesigning the lnb
unless this guy has $50,000 worth of equipment to do so it will never happen.
they probably sell the lnb he is looking for.
what does he want to receive at that frequency????
ralph

Sorry for the misunderstanding Ralph,

I did not say he was going to mod the unit to 14 gig, but when using any test equipment for any project you should select equipment that will cover the range you need and then some so your not working at the stops or limitations of the test equipment, the spectrum analyzer being used should work out to 3 times the design frequency of the device under test, this is to look for 3rd order harmonics or intermod.

If your going to try and work on a LNB your going to need some sort of test equipment to make sure your not going to be affecting the guy down the street with some sort of spur or harmonic you have accidentally created by changing something in the LNB.

Or testing it to see if the smoke is still there.

 

[ralphmagno]

hello,
no problem .
i have adjusted the lo in lnb here to lower the range by 90 mhz on the 9.750 lo no problem.
also the upper range can be moved as well.
this was because there was a frequency of 10.660 ghz and normal lnbs and satellite receiver would not reach it.
since satellite tuners are from 950 mhz to 2150 it was just out of range.
lnb here cost 5 euro each for a single and 8 euro for a dual output.
are you in california??
ralph