[ICOM] Sherwood Engineering test numbers

[John Geiger]

Hi Jan,

You state:

"I own a 706MKIIG; it has a terrible receiver"

Then how did it score so well on the Sherwood
Engineering tests?  Better than a FT1000MP or FT1000D,
almost the same as a 775DSP?  This is what I find hard
to believe.

As someone who also teaches statistic and experimental
design, I trust numbers, and understand reliability
and validity.  But sometimes they do fool me.

Physists have "proven" that a bumblebee can't fly.

73s John W5TD

--- Jan Robbins <swanman at cfu.net> wrote:

> Hi John, et. al.,
> 
> There is NO MORE RELIABLE set of third-party
> measures of receiver 
> performance ANYWHERE in the world  than Rob's. 
> Whether you, in your 
> particular environment and set of needs, care about
> what he says, is 
> entirerly your business; there are many good reasons
> for buying this 
> radio or that (I own a 706MKIIG; it has a terrible
> receiver).  But NO 
> ONE, including ARRL labs, comes close to his
> validity and reliability 
> (if terms like "validity" and "reliability" are
> confusing, look 'em up 
> before you comment on somebody's systematic
> measurements; they are 
> well-known in the trade, one of the reasons why  no
> expert in 
> receiver/.transceiver performance I have ever heard
> of does not check 
> Rob's facts first). 
> 
> Many of us who've been involved with receiver
> performance and comparison 
> for years (in my case nearly 50) START with Rob's
> figures.  Unless you 
> can show us someone else who has BETTER methods of
> measurement AND more 
> experience (Rob has 30+ years of it, over many more
> receivers than 
> anyone else, as well as no vested interests in his
> comparisons), AND 
> more systematically gathered data  that is in any
> way contradictory to 
> his ( NO ONE, so far as I know, has ever been able
> to contradict his 
> reesults with equal valid/reliable measures), we
> will take Rob's data 
> anytime, and anybody else has to convince us
> otherwise--and not by 
> "personal experience" comments about some particular
> radio.
> 
> I have had many of the radios Rob measures here in
> my shack, and have 
> been fortunate enough to be able to run A/B tests on
> them.  In NO CASE 
> did Rob rate a radio better than my comparisons
> showed (Icom 7800 with 
> 3khz roofing filter wins hands down).  But that was
> nothing more than my 
> "personal experience."  A lifetime of training and
> research in 
> statistical design, measurement, and anlysis
> convinced me long before I 
> was able to make those in-shack comparisons that Rob
> was "the guy" in 
> estimating (and comparing) receiver performance.
> 
> I aplogize for being so vehement.  I have spent my
> life in statistical 
> data and analysis, and have been a ham since I was
> 15 (I'm now 63). No 
> one knows receiver performance better than Rob
> Sherwood.
> 
> Vy 73 to all!   Happy Fall (at least it is here in
> Iowa!).  Jan N0JR
> 
> 
> John Geiger wrote:
> 
> >How much stock does everyone place in the Sherwood
> >Engineering receiver test numbers
> (www.sherweng.com)? 
> >While I admit that the 2khz spacing is a much more
> >useful measurement than the 20khz the ARRL has used
> >for a long time, and I believe that Rob Sherwood
> knows
> >what he is talking about when he tests receivers, I
> >have a hard time believing some of his numbers.
> >
> >For example, he measures the 2khz IMD DR for the
> Icom
> >706MKIIG at 74db. This places it right in line with
> >the PROII and PROIII at 75db, and better than the
> >756PRO (71db), FT1000D (69db), FT1000mp MK V
> (69db),
> >and the Icom 746 (70db).  Now I have owned many of
> >these radios, and I did not find the 706MKIIG to
> have
> >that good of a receiver, definitely not better than
> >the 756PRO or the Yaesu FT1000 series.  It
> overloaded
> >pretty bad under contest conditions.  What am I
> >missing in his measurements, that makes the
> 706MKIIG
> >look so much better than these other radios?
> >
> >73s John W5TD 
> >
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