[Elecraft] K3 vs. HPSDR Mercury receiver

[N8LP]

For casual SSB operating I listen to my LP-PAN / PowerSDR panadapter which is
fed from ahead of the xtal filters, and for dabbling in contests or
operating CW (where latency can be an issue) I listen to the K3. I am not in
Europe where things can be dicey, but I have yet to see enough total peak
energy in the passband to affect the ADC of the panadapter.

73,
Larry N8LP





> Next generation transceivers will not use crystal filters 
> and mixers, they are already appearing and the performance 
> is outstanding.

If the next generation of transceivers does in fact abandon 
narrow filtering ahead of the ADC it will be a sorry step 
backward.  While some of the designs like the Flex-5000 and 
Peresus have excellent specs for the most part when tested 
against two tone situations, they are still substandard in 
dealing with multiple very strong in-band signals as would 
occur on 160/80/75 meters in a contest or on 40 meters with 
the multiple megapower broadcasters. 

To maintain linearity, an ADC must be able to withstand the 
instantaneous peak signal (vector sum - not average) from 
all the signals within its passband.  For some DSR designs 
that maintain bandwidths from several hundred KHz to 10s 
of MHz that peak signal handling capability requirement 
can be significant and represents a required dynamic range 
orders of magnitude greater than even the best current 
technology.  It is the multi-tone interference that is best 
handled by narrow filtering ahead of the ADC (e.g., the K3 
design).  

73, 

   ... Joe, W4TV 
 

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