Posted by
Bob Naumann W5OV on
Dec 31, 2010; 2:22pm
URL: http://elecraft.85.s1.nabble.com/Re-Latest-Sherwood-table-tp5882563p5882728.html
Thank you, Don.
To make what I'm saying clear, I do understand that this is all very complex
and decoding it all takes a deep level of understanding, which I suppose
comes naturally to engineers and people who enjoy that sort of thing. I'm no
longer one of those people. Even though I have been involved in electronics
for decades and was an Electronic Engineering Technician for many years
until I went to "the dark side" of management back in the 80's.
So, I can/could understand what each of the terms means - but I don't see
from the table how they were used to reach a conclusion of which radio is
ranked #1.
I guess that what I'm looking for is an "Executive Summary" with some
answers to my specific questions:
1) Why is the FT5000 at the top of the list? (And not the K3 when they both
get a 101 in the column the table is sorted on?) Is it because the FT5000 is
newer so it goes at the top?
2) Why no indication of what filter was used in the FT5000? (Is that
significant or not?)
3) What is the second sort column for the table? (which I presume "puts the
FT5000 on top" since they seem equivalent in the Narrow Dynamic Range column
with 101 for both).
I think that even if I were to gain enough knowledge to fully explain each
parameter in engineering terms, I would still be guessing at what criteria
Rob used to rank these radios.
A simple explanation like: "Even though the FT-5000 and the K3 have the same
Narrow Dynamic Range measurement, the _______ of the FT5000 puts it ahead of
the K3 in the table".
Make sense?
-Bob W5OV
-----Original Message-----
From:
[hidden email]
[mailto:
[hidden email]] On Behalf Of Don Wilhelm
Sent: Friday, December 31, 2010 7:54 AM
To: Bob Naumann
Cc:
[hidden email]
Subject: Re: [Elecraft] Latest Sherwood table
Bob,
I can't think of an easy answer - mainly because many or the parameters
tested are in the realmm of engineering, and as such use engineering
terms to achieve some level of communications clarity.
In short, if you do not develop some understanding of the terms, there
is no easy way and must involve some study.
I would suggest two things - first is to try looking up each of the
parameters on Wikipedia, second, do some study of the Receivers section
in the ARRL Handbook to provide you with some understanding of how the
various parameters work together. If you want to gain a little better
understanding, look at the ARRL Testing procedures (for Receivers) - you
really don't have to read the entire test procedure, usually the Purpose
of each test will provide some insight. You can find the ARRL Test
procedures at
http://www.arrl.org/files/file/Technology/tis/info/pdf/Procedure%20Manual%202010%20with%20page%20breaks.pdf
Lastly, some parameters will be more important to one type of operation
than others. Exactly which ones relate to your operating tastes and
style will vary. A contester or avid DXer will want good performance in
the narrow spaced dynamic range because he must work in a section of the
band crowded with signals and does not want the stronger ones to
overload the receiver. If your operating style is more of the ragchew
variety, that same parameter may not be important to you since you will
likely QSY if QRM is nearby rather than trying to "stick it out" and
work within the QRM area of the band.
73,
Don W3FPR
On 12/31/2010 7:42 AM, Bob Naumann wrote:
> Is there a non-engineer's guide to the Sherwood table for those of us who
> are not engineers?
>
> In particular, the table is sorted by Narrow Spaced Dynamic Range, and I
see
> that the FT5000 is listed first, but the K3 also gets a 101 in that
column,
> albeit with a "pf" footnote instead of just an "f".
>
> I decode these footnotes to be "f" = "Measurement was Phase-Noise Limited"
> And "pf" = "Measurement was Phase-Noise Limited" and was "with 200 Hz
5-pole
> filter"
>
> OK - so why is the FT5000 at the top of the list? Why no indication of
what
> filter was used in the FT5000?
>
> What is the second sort column for the table? What puts the FT5000 on
top?
>
> What does this table really tell us? It seems that both of these receivers
> are pretty close as many of the numbers are similarly different from those
> listed below them.
>
> When a parameter is higher or lower - which is better? I presume that the
> higher the narrow-spaced dynamic range, the better, but what about 100kHz
> blocking (for example). Is higher or lower there better? The K3 is a 140
on
> that one, and the FT5000 is a "lowly" 127. The Down-conversion Kenwood
590
> gets a 144 in this column - is that better or worse than the K3? But, the
> 590 only gets an 88 in the narrow-spaced dynamic range, so I guess that
> means it's much worse?
>
> How does one interpret this data?
>
> 73,
>
> Bob W5OV
>
>
>
>
>
>
>
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]] On Behalf Of Bil Tippett
> Sent: Friday, December 31, 2010 6:18 AM
> To:
[hidden email]
> Subject: Re: [Elecraft] Latest Sherwood table
>
> > I wonder how such a high performance filter would work in the K3?
> Not that its
> needed in the K3. However in the interest of science, it might be a
worthy
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