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" <n...@elecraft.com>
To: "Chester Alderman" <alderm...@windstream.net>
Cc: "Elecraft Reflector" <Elecraft@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 <n...@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" <alderm...@windstream.net>
> wrote:
>
>>
>>
>> _____________________________________________
>> From: Chester Alderman [mailto:alderm...@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-boun...@mailman.qth.net] On Behalf Of Yngvi
>> (TF3Y)
>> Sent: Tuesday, February 24, 2015 1:26 PM
>> To: elecraft@mailman.qth.net <mailto:elecraft@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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