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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