[Elecraft] Sherwood Engineering Tests
jim
jbollit at outlook.com
Tue Feb 24 14:19:08 EST 2015
Wayne,
Thanks again. I hear a significant amount of hiss with the AF gain control
at zero.
I am going to send it in and post the results upon return.
Tnx
Jim
W6AIM
-----Original Message-----
From: Wayne Burdick [mailto:n6kr at elecraft.com]
Sent: Tuesday, February 24, 2015 11:03 AM
To: jim
Cc: 'Wes (N7WS)'; elecraft at mailman.qth.net
Subject: Re: [Elecraft] Sherwood Engineering Tests
Jim,
Yes, you have the new DSP boards. I'm sure customer support will check out
your audio as requested.
There will always be noise and hiss with no signal present and gain controls
maximized, because the K3 has a lot of gain in the RX signal path, like any
modern transceiver. But with AF gain, RF gain and preamp settings
appropriately adjusted, even the noise from a very poor antenna will
completely dominate any noise generated within the radio itself. If not, you
have something set up incorrectly, or a hardware issue that CS will be able
to identify.
The new synths are not required just to produce clean audio. It should
already be clean.
73,
Wayne
N6KR
On Feb 24, 2015, at 10:50 AM, jim <jbollit at outlook.com> wrote:
> 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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