[Elecraft] Sherwood Engineering Tests

Tue Feb 24 13:50:13 EST 2015

Wayne,

Thanks.

My Serial Number is  04841.  I was told the LPF was "most likely" in my
radio and I have not taken it apart to see if that is the case.

DSP 1 and DSP 2 are at 02.83

MCU is at 04.86

As I stated in a mail I sent to the reflector, two days ago, I will be
sending in my K3 on RMA to have you review and update where necessary.  I
will include a request to have Elecraft look at the audio spectra to make
sure it is **clean**. 

Are the new Synth's needed for better audio performance?  The **noise and
hiss* is present with no signals present in the bandwidth of the 400 Hz
crystal filter (or for that matter, any of the filters choosen).

Look forward to seeing the results of the repair/update and will post my
results.

Jim
W6AIM

-----Original Message-----
From: Wayne Burdick [mailto:n6kr at elecraft.com] 
Sent: Tuesday, February 24, 2015 9:28 AM
To: jim
Cc: 'Wes (N7WS)'; elecraft at mailman.qth.net
Subject: Re: [Elecraft] Sherwood Engineering Tests

Jim (et al),

The K3's audio has improved due to three factors in the past couple of
years:

- a low-noise, low-pass audio filter stage was added to the DSP board,
eliminating high-pitched CODEC artifacts

- DSP firmware changes were made to correct AGC linearity and eliminate a
CODEC quantization problem

- main MCU firmware was modified to allow the user to select the lower AF
cutoff in CW mode (100/200/300 Hz) by adjusting the lower edge of the
crystal filters

With the above changes in place, we carefully measured the K3's audio
spectra and compared it to other radios with the same type of class-AB final
AF amplifier IC (most transceivers fall into this category). They are all
virtually identical. 

Rob, too, told us that the audio spectra he measured on a recent K3 (with
new synths and the latest DSP and MCU firmware) was significantly improved
from the K3 he measured several years ago.

While it is possible to reduce audio IMD products even further, this
typically requires a class-A final audio output stage, which would add
perhaps 0.5 to 1.0 amps of additional receive-mode current drain (and an
associated heatsink). That is inconsistent with the K3's intended usage,
which includes excellent power efficiency for portable applications (Field
Day/DXpedition/travel). Also, most users would not notice such a subtle
change.

73,
Wayne
N6KR

On Feb 24, 2015, at 8:19 AM, jim <jbollit at outlook.com> wrote:

> Wes,
> 
> I agree, and if you look at a post I made a couple days ago, it states
that.
> Sherwood also states his list is sorted on one column and people shud 
> take all factors into account when choosing a radio.
> 
> I would NOT recommend a K3 for it's audio.  
> 
> Each person has their needs and should review them carefully.  I would 
> also not recommend a Drake R4-C, even though it is in the top quartile.
> 
> I will send you a copy of an earlier post that I made.
> 
> 
> Jim
> W6AIM
> 
> 
> 
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of 
> Wes
> (N7WS)
> Sent: Tuesday, February 24, 2015 6:12 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Sherwood Engineering Tests
> 
> I'm sure there's a point here and I just fail to see what it is.
> 
> Rob has stated many times (look for his videos) that one number does 
> not a radio make.  In fact, as best that I know, he doesn't own a K3.
> 
> Wes  N7WS
> 
> On 2/23/2015 11:01 PM, jim wrote:
>> Guys,
>> 
>> Further, pesky, facts on said Real Radio at 
>> http://www.sherweng.com/table.html .
>> 
>> Number two on the list.  That is out of 116 receivers listed on the 
>> Sherwood page.
>> 
>> That puts said Real Radio in the top 3% of the radios Bob Sherwood 
>> has tested for a critical receiver performance parameter.
>> 
>> BTW, you will have to use the "Page Down" button, more than twice, to 
>> even get a hint of the Kenwood 590.  It is number 20 on the list, 
>> putting it in the top 17%
>> 
>> Also, important to note, is the Drake R4-C with the Sherwood roofing 
>> mod, listed at number 28.  The R4-C is *ONLY*
>> 45 (forty five) year old technology and that puts it in the top 23%.  
>> Yep, FORTY FIVE year old technology.  Yep, top 23 %.
>> 
>> Just some further, pesky, facts.........................
>> 
>> Rake
>> 
>> P.S.  BTW, I learned 45 years ago.  This flies in the face of 
>> someone's comment that I never learn.
>> 
>> Ho Hum, another pesky fact.............
>> 
>> 
>> 
>> 
>> 
>> 
> 
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