[Elecraft] Latest Sherwood table

Fri Dec 31 09:22:30 EST 2010

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: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Friday, December 31, 2010 7:54 AM
To: Bob Naumann
Cc: elecraft at mailman.qth.net
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%20
2010%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: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bil Tippett
> Sent: Friday, December 31, 2010 6:18 AM
> To: elecraft at mailman.qth.net
> 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
> pursuit. It also might push the K3 well ahead of the FT5000 in ultimate
> performance.
>
> Not very well since it's at 70 MHz.  ;-)  The Inrad filters are
> already better than whatever is in the FT5000 since Sherwood measured
> ultimate rejection in the K3 at 105 dB vs 90 dB for the 5000.
>
> 73,  Bill  W4ZV
>
>
>
>
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