[Elecraft] K3 or SDR-5000?

[Joe Subich, W4TV]

> what do you think other than the obvious differences (knobs, 
> bandscope, computer, $$, etc.) K3 or SDR-5000?

The design philosophy of the two radios is completely different.
 
The Flex-5000 front end is "broad as a barn door" - it applies all 
the energy in an entire amateur band and adjacent frequencies 
directly to the DSP analog to digital converter.  This does two 
things.  First the ADC is required to have a much greater dynamic 
range in order to deal with a 10 to 20 dB larger but very low 
probability instantaneous peak voltage (very high peak to average 
ratio).  Second it requires the DSP software to sort out all the 
signals in roughly a 200 kHz "window."  This results in increased 
processing time and more delay.    

The front end of the K3 has a narrow "roofing" filter very close 
to the first mixer which limits the bandwidth applied to the DSP 
ADC.  This provides two advantages.  The peak to average ratio 
of the signal applied to the ADC is not a high so the dynamic 
range of the ADC can be better used (better optimized to conditions) 
which theoretically provides better dynamic range (either better 
sensitivity or more resistance to IMD).  Secondly, by dealing with 
a more narrow spectrum, the DSP can be made faster for equivalent 
resolution (selectivity) or the available processing power/time 
can be used for improved performance like, noise reduction/signal 
correlation, context and focus filtering, spatial processing, etc. 

The Flex philosophy has an advantage in that it can implement 
in-band dual receive with a single set of receiver hardware.  Its 
DSP can demodulate any signal within the 196 KHz "window" and 
provide one signal on each audio channel. With a multi-channel 
audio card or multiple audio cads and enough computing power, 
the Flex can be extended to "n-channel receive" without additional 
hardware.  The K3 design is limited to a single signal per DSP 
channel.  

Both design philosophies have their place.  The K3 is like a high 
performance sports car - it does one thing and does it better than 
any other product.  The Flex-5000 is like a fully loaded luxury 
SUV - it has every option imaginable but it lacks precision, 
handling and speed. 

Your choice depends on whether you want frills or performance. 

73, 

   ... Joe, W4TV 
 


> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Ross Stenberg
> Sent: Saturday, December 22, 2007 1:12 PM
> To: Elecraft at mailman.qth.net
> Subject: [Elecraft] K3 or SDR-5000?
> 
> 
> I realize that this is like asking a pack of dogs if they 
> like bacon, but
> what do you think other than the obvious differences (knobs, 
> bandscope,
> computer, $$, etc.) K3 or SDR-5000?
> 
> 73 and Merry Christmas
> 
> Ross Stenberg
> K9COX
> 
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft    
> 
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
> 
>