Even a "QRP" rig for digital use only will have these same problems  
that have to be examined and subsystems properly designed and built.   
A 'simple' audio amp in a tranceiver may work fine for SSB voice,  
but may have amplitude and phase variations over the designed  
bandwidth that can adversely effect a multi-tone digital signal.   
Certainly, mixers, diplexers, filters, and rf/if amps used over  
broad ranges of frequencies like 1.8 mHz to 30 mHz can have  
substantial effects also.  
  
I think what you're really pointing out is that more careful design  
and more costly circuits than what is available in the average ham  
radio may be needed in order to optimize the handling of digital 
signals.  
  
Jim  
WA0LYK  
  
--- In [email protected], "Charles Crizer" <[EMAIL PROTECTED]>  
wrote:  
>  
> Spot on.  
>   
> What about desgining and building a "QRP" radio for digital use.   
>   
> Its seems to me that some of the problems you mention are because  
the radio  
> is made for many modes. What if the radio was just build for RTTY,  
PACKET,  
> PSK31, PACTOR, etc?   
>   
> Instead of a 300-3500Hz audio bandwidth, it could be much tighter  
and  
> desigend for the exact mode being used. After all, isn't that the  
way CW QRP  
> rigs are desigend? They only have to work with a very narrow  
bandwidth.   
>   
> Charlie Crizer, KF4MNE  
> Fairfax County (Alexandria) Virginia, US  
> QTH: 38-47.96N / 77-05.17W - FM18kt  
> [EMAIL PROTECTED]  
> [EMAIL PROTECTED]  - Winlink2000/Airmail  
>   
  






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