[Elecraft] K3 and Perseus SDR as a 2nd RX

[SSB Electronic USA]

On November 16 Bill W4ZV wrote:
>
> Also be aware that Blocking Dynamic Range (BDR) for the Perseus is
> relatively poor, as is true for all current SDRs.  BDR is 99 dB at 2 kHz 
> and
> 117 dB at 20 kHz versus 139 dB for both 2 and 20 kHz, per ARRL Product
> Reviews.  If you have strong neighbors (either commercial or amateur
> stations), the Perseus will need additional filtering to prevent strong
> signals from overloading the front-end.

There is no need for additional filtering since the Perseus has 9 six pole 
front-end bandpass filters (1.7 - 30 MHz.) plus a 3 pole low pass for 10 
kHz. - 1.7 MHz.)

Today, SSB Electronic USA received an email from the ARRL acknowledging that 
errors were made in the measurement of the Perseus SDR.

Over the past year, extensive measurements have been conducted not only by 
Nico Palermo IV3NWV at Microtelecom but by Lief Asbrink SM5BSZ and Rob 
Sherwood NC0B.
The Blocking Dynamic Range (BDR) numbers measured by all of the above were 
much better (125 dB)  than the figures that were published by the League. 
In addition, the IMD Dynamic Range figures published in QST reflect 
differences at various spacings.  In an SDR such as the Perseus, the IMD 
Dynamic Range will be the same at 2 kHz, 5 kHz. or 20 kHz.

The ARRL is currently in the process of taking another look and they should 
be commended for doing so.  I am sure updated figures will be published in 
the near future.

Please don't accuse me of being biased just because I am the US Perseus 
distributor.  I also own a K3 s/n 1519 as well as a Perseus.   Both are 
great radio's.

I would like to commend Eric and Wayne at Elecraft, Nico at Microtelecom as 
well as Phil Covington for their contributions to receiver design and ham 
radio and ..... last but not least the ARRL and Rob Sherwood for all the 
reviews and measurements that give us something to think about and discuss 
when we're not playing radio.

73's
Gerry Rodski K3MKZ
SSB Electronic USA




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