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[Amps] Antenna vs. amp (was: al-1200 question)

To: <amps@contesting.com>
Subject: [Amps] Antenna vs. amp (was: al-1200 question)
From: W8JI@contesting.com (Tom Rauch)
Date: Wed, 13 Mar 2002 04:27:31 -0500
Please don't attribute any statement noise should be the same 
regardless of directive pattern to me! 
  
> Rx noise figure measured 1.5-1.8dB.

That doesn't mean anything definitive. It might be sufficient, it might 
not be.

When one receiver has wider bandwidth than another, noise figure 
becomes less important in the wider receiver. That's because noise 
is broad spectrum, and so noise power increases directly with 
bandwidth. A receiver using wide filters limits on external noise 
much earlier than one using narrow filters. 

Also ambient noise varies with direction, location, and frequency. 
Whatever you are using, you should always hear a clear increase 
in noise when you switch from a dummy load to the antenna while 
using the narrowest expected filter in the most quiet direction....or 
your system is noise figure or gain limited. 

> I think there should have been, given the typical figures in noise
> temperature charts.

Charts cause headaches.

Any answer you read or see will be for one particular situation.
73, Tom W8JI
W8JI@contesting.com 

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