[Elecraft] Sherwood Engineering Tests

Tue Feb 24 13:25:55 EST 2015

These are interesting stats.

One thing I noticed was the apparent loss in sensitivity as measured by
Sherwood. This is probably not a big issue for most these days with the
ever increasing noise levels but for the few in silent locations, incl.
some DXpeditions this might be an issue.

Any comments on this?

73, Yngvi TF3Y
http://www.tf3y.net

On Tue, Feb 24, 2015 at 5:48 PM, Wayne Burdick <n6kr at elecraft.com> wrote:

> Hi George,
>
> I just checked the web site and I see that we've been shipping K3s with
> the new DSP board since sometime in 2010. (Confirming that time flies.)
>
> You can upgrade the DSP board from rev. C to rev. D for $109 (K3DSPUPGD);
> this includes both the audio low-pass filter and a bit of an improvement in
> LF audio response. Or you can add just the audio filter section as a small
> daughter board for $39 (K3DSPLPF).
>
> The upgrade does improve the spectra as viewed on an audio spectrum
> analyzer, but many operators won't be able to hear the effects by ear.
> Those who can hear them have told us it was a major improvement.
>
> Wayne
> N6KR
>
>
>
> On Feb 24, 2015, at 9:40 AM, George Dubovsky <n4ua.va at gmail.com> wrote:
>
> >
> >
> > On Tue, Feb 24, 2015 at 12:27 PM, Wayne Burdick <n6kr at elecraft.com>
> wrote:
> > 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
> >
> > Approximately what serial number introduced this change? Thanks.
> >
> > 73,
> >
> > geo - n4ua
> >
> > - 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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