[time-nuts] how to find low noise transistors

KA2WEU at aol.com KA2WEU at aol.com
Sat Jul 18 18:36:13 EDT 2015


Good afternoon,
 
another low noise recommended transistor is the 
 
http://www.cel.com/pdf/datasheets/ne856m02.pdf and  for frequencies below 
10 Mhz
 
the 2N2857.  This nice  fact is that the AF and KF values  are published, 
the bad part is the the AF=1 value violates the law of  physics.
 
http://www.microsemi.com/existing-parts/parts/47966
 
http://espice.ugr.es/espice/src/modelos_subckt/spice_complete/RF.LIB
 
Be careful !
 
Who says EE is easy.
 
Best regards , Ulrich N1UL 
 
 
 
In a message dated 7/18/2015 3:56:53 P.M. Eastern Daylight Time,  
time-nuts at febo.com writes:

Good  afternoon, 

There is a problem in the literature that people confuse  the  "spot noise 
figure" and the "large signal " noise properties.  Here AF and KF  needs to 
be 
known and considered.


Here is  the mathematical correct  formula in a Word for Windows Form   
attached file.
If you use it for publications, please quote me . Thanks  

My advise is take a BIP transistor , fT not much more then 20 x  operating  
frequency  (lower flicker component) and operate it  at 15 to 20 % of  
ICmax.

The BFG540 is amongst the best  Oscillators  oscillators  

http://www.nxp.com/documents/data_sheet/BFG540_X_XR_N.pdf

Now  you outperform most colleagues 

73 de Ulrich  N1UL

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In  a message dated 7/18/2015 1:19:57 P.M. Eastern Daylight Time,   
pete at petelancashire.com  writes:



https://scholar.google.com/scholar?q=measuring+transistor+noise&hl=en&as_sdt
=0&as_vis=1&oi=scholart





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