[Elecraft] K3 & ADAT ADT-200A by HB9CBU

[Alan Bloom]

On Mon, 2008-12-01 at 06:35, ab2tc wrote:
> Hi,
> 
> I, too, would be very interested in seeing how "entire HF spectrum digitized
> at once" receivers would fare in the real world. I am *very* skeptical.
> Although the Perseus (with that architecture) receiver fares relatively well
> in the recent ARRL test, 

It compares well for third-order intermodulation distortion, but not for
blocking dynamic range.  The A/D converter is very linear within its
range, so you can get some fantastic TOI (third-order intercept) numbers
if you measure with signals near the top of the ADC range.  However the
ADC full-scale signal level is less than a conventional mixer can
handle.

> the testing completely ignores what happens when
> there are not *two* but thousands of strong signals in the passband. 

Exactly.

> With
> this new architecture, it's imperative that ARRL and other labs find other
> ways of evaluating real world performance as a simple two-tone test becomes
> completely irrelevant.
> 
> Toby Deinhardt wrote:
> > 
> > Hi,
> > 
> > has anybody done a serious test of the ADT-200A transceiver yet?
> > 
> > <http://www.adat.ch/index_e.html>
> > <http://www.adat.ch/pub/Presentation_Hamfest_22-09-07.pdf>
> > <http://www.adat.ch/pub/ADT-200A_Messresultate_V10.pdf>
> > 
> > It would be rather interesting to see how the concept used by the K3 (24 
> > bit digitalization after IF) compares in the real world to the early 14 
> > bit digitalization as used by the ADT-200A (and afaik by the Perseus RX 
> > from Microtelecom), especially with the chips available currently.
> > <snip>
> > 
> > 
> 
> 
> -----
> AB2TC - Knut

Al N1AL