[Elecraft] FW: Sherwood Engineering Tests

Wed Feb 25 14:19:19 EST 2015

Progress lurches forward.

Someone I am sure asked "what are we going to use this high temperature
material for, we are never going to the moon"

Jim
W6AIM

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
Stewart
Sent: Wednesday, February 25, 2015 12:11 AM
To: k3ndm at comcast.net; Burdick, Wayne
Cc: elecraft
Subject: Re: [Elecraft] FW: Sherwood Engineering Tests

I can't help thinking that we are getting to a point where this number
chasing is irrelevant.

Until high noise levels caused by EMI and the poor transmitted signals
during DX hunting and contests are eliminated, further improvements in
receive performance figures are unlikely to be of much practical value.

My 2p's worth...

73
Stewart G3RXQ

On Wed, 25 Feb 2015 01:56:22 +0000 (UTC), k3ndm at comcast.net wrote:
> I'm old enough to remember that the most important characteristic of a
receiver was sensitivity. Nothing else seemed to matter. Some receivers of
the time had 2 RF amplifiers to make sure that they won the sensitivity
battle. And, what would happened when a strong signal, not necessarily S9,
would appear, bad things happened to your radio. At this point I won't
define the date.
>
> This lunacy was being looked at by a number engineers, to include Dr. 
> Ulrich
Rhode, W2 something. I forget his call. He said in a series of papers in
professional journals and Ham Radio Magazine that sensitivity was not the
most important parameter at the time. It would turn out to be LO noise
sidebands and dynamic range. That still holds today, and now, IMHO, ultimate
rejection should be added. All of this is shown in Sherwood's data. What
this all means is that all of the receiver parameters must be looked at to
decide what makes a great radio. I suggest a review of some of Rhode's
papers. His writings make extremely interesting reading as it addresses this
discussion directly.
>
> 73,
> Barry
> K3NDM
>
>
> ----- Original Message -----
>
> From: "Wayne Burdick" <n6kr at elecraft.com>
> To: "Chester Alderman" <aldermant at windstream.net>
> Cc: "Elecraft Reflector" <Elecraft at mailman.qth.net>
> Sent: Tuesday, February 24, 2015 4:57:23 PM
> Subject: Re: [Elecraft] FW: Sherwood Engineering Tests
>
> Just to complete the point about this: The K3 tested probably didn't 
> have its
S-meter calibration ("RX gain cal") completed before we sent it to Rob, an
oversight on our part. This procedure is fully automated by the K3 Utility
program, and definitely would have corrected the sensitivity threshold issue
Rob observed.
>
> 73,
> Wayne
> N6KR
>
>
> On Feb 24, 2015, at 1:54 PM, Wayne Burdick <n6kr at elecraft.com> wrote:
>
>> Some on this list are still mistaking this column of Sherwood's chart 
>> as
*receiver sensitivity*. I believe it is a measurement of AGC threshold. The
K3's receiver sensitivity (MDS) is excellent by any measure; see the "noise
floor" 
column. (Side-note: It's interesting that the preamp-off sensitivity of the
tested K3 was -136 dBm, while that of the Flex 6700 was -118 dBm -- an 18-dB
difference. One would have to leave the preamp ON much more often with the
'6700. As Sherwood noted, this maximizes the '6700's dynamic range, but
you'd also be hitting the A/D that much harder.)
>>
>> 73,
>> Wayne
>> N6KR
>>
>>
>> On Feb 24, 2015, at 12:24 PM, "Chester Alderman" 
>> <aldermant at windstream.net>
wrote:
>>>
>>>
>>> _____________________________________________
>>> From: Chester Alderman [mailto:aldermant at windstream.net]
>>> Sent: Tuesday, February 24, 2015 1:59 PM
>>> To: 'Yngvi (TF3Y)'
>>> Cc: 'Elecraft Reflector'
>>> Subject: RE: [Elecraft] Sherwood Engineering Tests
>>>
>>>
>>> Hi Yvgvi,
>>>
>>> I wonder, given atmospheric noise levels, if that is really going to 
>>> be noticed by the operator. I seriously doubt It would be noticed in a
contest?
>>>
>>> 73,
>>> Tom - W4BQF
>>>
>>>
>>> -----Original Message-----
>>> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf 
>>> Of Yngvi
>>> (TF3Y)
>>> Sent: Tuesday, February 24, 2015 1:26 PM
>>> To: elecraft at mailman.qth.net <mailto:elecraft at mailman.qth.net>
>>> Subject: Re: [Elecraft] Sherwood Engineering Tests
>>>
>>> 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
>>>
>>>
>>> ______________________________________________________________
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>>> This list hosted by: http://www.qsl.net Please help support this 
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>>> n6kr at elecraft.com
>>
>> ______________________________________________________________
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>
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> stewart at twinwood.me

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