[hpsdr] Predistortion and different types of amplifiers?

[Kjeld Bülow Thomsen]

Hi All,
 
In the referenced DUBUS article SM5BSZ is talking about broadband TX-noise
where the cure is filtering. Predistortion suppresses IMD and that’s another
issue.
 

Vy 73 de OZ1FF - Kjeld

 

Flex & Hermes user

 

 <http://www.oz1ff.dk/> http://www.oz1ff.dk

 
 
Hi All,
 
The current state of the art with PureSignal 
< <http://www.n9vv.com/Images/Apache-Labs/PureSignal.pdf>
http://www.n9vv.com/Images/Apache-Labs/PureSignal.pdf> on HPSDR and 
also Stefan's work with the N2ADR 
< <http://dl2stg.de/stefan/hiqsdr/gnuradio.html>
http://dl2stg.de/stefan/hiqsdr/gnuradio.html> transceiver is exciting!  
I read each new post with high interest, and I guess this post will 
hopefully spark some more.  :-)  I am really curious how well it works 
on different types of amplifiers.  So please pipe up if you have any 
experience with any of these:
 
1)  From what I've seen, the high voltage (50 V) LDMOS seems to work well.
2)  My memory says that I read somewhere that lower voltage solid state 
amps don't work very well.
     a)  Is this true, and if so is it true for both BJT and FET amps?
3)  How does it work with vacuum tube amps?
 
With the advent of SDRs showing the spectrum to everyone, and now with 
predistortion, we might see hope for a big improvement in transmitted 
signals, but this article < <http://www.sm5bsz.com/dynrange/dubus313.pdf>
http://www.sm5bsz.com/dynrange/dubus313.pdf> 
shows that some popular SDR transmitters end up at the bottom of the list.
 
Thanks to all of you who have posted test results to the list, and to 
those developing the code to enable the tests.  I look forward to more 
great results!
 
73,
 
Rob
KL7NA

 

 

 

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