Can anyone tell me the noise figure i dB for 13K and 17K C-band LNB heads?
Jan

On Tue, 1 Jul 2008 15:10:52 +0200, "Jan Lustrup"  wrote:

>Can anyone tell me the noise figure i dB for 13K and 17K C-band LNB heads?
>Jan 
>


Noise Figure (NF) = 10 * log (Noise factor)     dB 

Dave

Jan Lustrup wrote:
> Can anyone tell me the noise figure i dB for 13K and 17K C-band LNB heads?

NF = 10log10 (Te/To + 1) where To = 290K

So, for the 1st case 13K = 0.19dB and for the 2nd 17K = 0.247dB

-- 

Brian

On Tue, 1 Jul 2008 15:10:52 +0200, "Jan Lustrup" 
wrote:

>Can anyone tell me the noise figure i dB for 13K and 17K C-band LNB heads?
>Jan 
>
http://www.satellite-calculations.com/Satellite/noisefigure.htm

wrote in message 
news:rkbk645f8csbd8fksc1gvldtndnkgtd28p@4ax.com...
> On Tue, 1 Jul 2008 15:10:52 +0200, "Jan Lustrup"  wrote:
>
>>Can anyone tell me the noise figure i dB for 13K and 17K C-band LNB heads?
>>Jan
>>
>
>
> Noise Figure (NF) = 10 * log (Noise factor)     dB
>
> Dave

Yes that is half the story!!


NF =10 log((Te/To)+1) where Te is the noise temp and To in normally 290K

so 13K = 10 log(13/290+1) = 0.19

and 17K = 0.247

73
Jeff

>
>Jeff 
>

Yes Jeff

I gave him a start to let him go on and find out for himself.  Self learning.
A little pointer goes a long way.  You'll notice Brian gave a fuller answer
and even the figures.

Dave

Thanks Jeff....
and Dave, thanks for your quick answer, But I do not think I could have 
found it out by myself! ;)

Now I must start to convert these babies to the 9cm ham band!


PS:  Testing the Y factor "quite sky and ground" is appx 5 dB difference 
sky/ground.
On 4 GHz they gave me 4dB of Sun noise (13K model) with a one meter offset 
dish...the 17K model only 3,2dB of Sun noise.
Adjusting the scalar ring make a BIG difference on sidelobe noise from the 
ground, but did not do much in terms og forward gain.
Using 12 GHz Ku LNB (with a 0.2dB noise figure) that one gave me also  5dB Y 
factor, while the Sun noise was appx 9dB over quite sky.

73's LA3EQ Jan





"Jeff"  skrev i melding 
news:486a38ab$0$1344$834e42db@reader.greatnowhere.com...
>
>  wrote in message 
> news:rkbk645f8csbd8fksc1gvldtndnkgtd28p@4ax.com...
>> On Tue, 1 Jul 2008 15:10:52 +0200, "Jan Lustrup"  
>> wrote:
>>
>>>Can anyone tell me the noise figure i dB for 13K and 17K C-band LNB 
>>>heads?
>>>Jan
>>>
>>
>>
>> Noise Figure (NF) = 10 * log (Noise factor)     dB
>>
>> Dave
>
> Yes that is half the story!!
>
>
> NF =10 log((Te/To)+1) where Te is the noise temp and To in normally 290K
>
> so 13K = 10 log(13/290+1) = 0.19
>
> and 17K = 0.247
>
> 73
> Jeff
>

wrote in message 
news:ldek64pppqhkd3cv0afq557bpaoqbm2fli@4ax.com...
> >
>>Jeff
>>
>
> Yes Jeff
>
> I gave him a start to let him go on and find out for himself.  Self 
> learning.
> A little pointer goes a long way.  You'll notice Brian gave a fuller 
> answer
> and even the figures.

as did I

73
Jeff