Sherwood Receiver Test Data - K3S Added Today

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Sherwood Receiver Test Data - K3S Added Today

Bill Breeden

Rob Sherwood added the K3S to his Receiver Test Data page today.

73,

Bill - NA5DX

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Re: Sherwood Receiver Test Data - K3S Added Today

Steve Ellington-2
Looks like the K3S should be above the Flex because the Flex achieved 2DB
higher due to:

Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."

Congratulations K3S
Steve N4LQ

On Tue, Nov 10, 2015 at 6:48 PM, Bill Breeden <[hidden email]>
wrote:

>
> Rob Sherwood added the K3S to his Receiver Test Data page today.
>
> 73,
>
> Bill - NA5DX
>
> ______________________________________________________________
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Re: Sherwood Receiver Test Data - K3S Added Today

Joe Subich, W4TV-4

Of note - the K3S and K3 with new synthesizers were essentially +/-
1 dB of each other and swapping the advantage from test to test.
This is good news for owners of the original K3 - the synthesizer
upgrade will provide every bit of the performance "upgrade" in the
K3S.

> Looks like the K3S should be above the Flex because the Flex achieved
> 2DB higher due to:
 >
> Footnote Y --- "This is a testing anomaly of a direct-sampling
> receiver."

Yes, the Flex-67000 should be dropped significantly because it can not
produce the both claimed dynamic range and noise floor (weak signal
sensitivity) at the same time.  Multiple -30 dBm (105 dB DR referenced
to -135 dBm MDS) signals will cause ADC overflow with noticeable
clicking and popping (distortion) with the preamplifier enabled.  Turn
off the preamplifier to prevent ADC overflow and the MDS degrades to
-118 dB (nearly 20 dB less sensitive) and completely unsatisfactory
above 20 MHz or so.

73,

    ... Joe, W4TV


On 11/10/2015 6:58 PM, Steve Ellington wrote:

> Looks like the K3S should be above the Flex because the Flex achieved 2DB
> higher due to:
>
> Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."
>
> Congratulations K3S
> Steve N4LQ
>
> On Tue, Nov 10, 2015 at 6:48 PM, Bill Breeden <[hidden email]>
> wrote:
>
>>
>> Rob Sherwood added the K3S to his Receiver Test Data page today.
>>
>> 73,
>>
>> Bill - NA5DX
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
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Re: Sherwood Receiver Test Data - K3S Added Today

k6dgw
In reply to this post by Steve Ellington-2
Question from a mathematics major [whose parents wanted him to be a EE]:

In a direct-sampling receiver, how do you control the input level to the
ADC to achieve maximum available dynamic range without clipping at the ADC?

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

On 11/10/2015 3:58 PM, Steve Ellington wrote:
> Looks like the K3S should be above the Flex because the Flex achieved 2DB
> higher due to:
>
> Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."
>
> Congratulations K3S
> Steve N4LQ

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Re: Sherwood Receiver Test Data - K3S Added Today

Gary Gregory-2
In reply to this post by Joe Subich, W4TV-4
Joe,

Pity this distinct difference is not advertised widely for those folks not well versed in the importance of receiver specs.

But I have to add that lurking on this reflector is certainly a good way to learn what is important when evaluating a transceiver.

I place great emphasis on receiver specs and antenna selection. These to me are the most important.

You gotta here them to work them.

Glad I upgraded my K3 (2007) vintage, guess now mine can be termed a boat anchor?

73

Gary

-----Original Message-----
From: "Joe Subich, W4TV" <[hidden email]>
Sent: ‎11/‎11/‎2015 10:25 AM
To: "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today


Of note - the K3S and K3 with new synthesizers were essentially +/-
1 dB of each other and swapping the advantage from test to test.
This is good news for owners of the original K3 - the synthesizer
upgrade will provide every bit of the performance "upgrade" in the
K3S.

> Looks like the K3S should be above the Flex because the Flex achieved
> 2DB higher due to:
 >
> Footnote Y --- "This is a testing anomaly of a direct-sampling
> receiver."

Yes, the Flex-67000 should be dropped significantly because it can not
produce the both claimed dynamic range and noise floor (weak signal
sensitivity) at the same time.  Multiple -30 dBm (105 dB DR referenced
to -135 dBm MDS) signals will cause ADC overflow with noticeable
clicking and popping (distortion) with the preamplifier enabled.  Turn
off the preamplifier to prevent ADC overflow and the MDS degrades to
-118 dB (nearly 20 dB less sensitive) and completely unsatisfactory
above 20 MHz or so.

73,

    ... Joe, W4TV


On 11/10/2015 6:58 PM, Steve Ellington wrote:

> Looks like the K3S should be above the Flex because the Flex achieved 2DB
> higher due to:
>
> Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."
>
> Congratulations K3S
> Steve N4LQ
>
> On Tue, Nov 10, 2015 at 6:48 PM, Bill Breeden <[hidden email]>
> wrote:
>
>>
>> Rob Sherwood added the K3S to his Receiver Test Data page today.
>>
>> 73,
>>
>> Bill - NA5DX
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
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Re: Sherwood Receiver Test Data - K3S Added Today

Don Wilhelm-4
Gary,

By definition, a boat anchor has vacuum tubes that glow, and have to be
more than 40 years old (my definition).
Ohhh, and they need to include a power transformer which gives them
enough weight to allow them to sink to the bottom of the lake.

73,
Don W3FPR

On 11/10/2015 7:34 PM, Gary wrote:
> Glad I upgraded my K3 (2007) vintage, guess now mine can be termed a boat anchor?
>
>

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Re: Sherwood Receiver Test Data - K3S Added Today

Gary Gregory-2
Dang!

Gee whizz I'm too young, I don't glow in the dark, I'm too skinny and I can swim.

Anything else wrong with me Don.

The nice young man in the white coat hasn't been to see me lately either, another problem maybe?

Chuckle

Gaey

-----Original Message-----
From: "Don Wilhelm" <[hidden email]>
Sent: ‎11/‎11/‎2015 10:43 AM
To: "Gary" <[hidden email]>; "Joe Subich, W4TV" <[hidden email]>; "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today

Gary,

By definition, a boat anchor has vacuum tubes that glow, and have to be
more than 40 years old (my definition).
Ohhh, and they need to include a power transformer which gives them
enough weight to allow them to sink to the bottom of the lake.

73,
Don W3FPR

On 11/10/2015 7:34 PM, Gary wrote:
> Glad I upgraded my K3 (2007) vintage, guess now mine can be termed a boat anchor?
>
>

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Re: Sherwood Receiver Test Data - K3S Added Today

Don Wilhelm-4
In reply to this post by k6dgw
Fred,

Isn't that what the RF Gain control or input attenuator is used for?
The ADC does not simply clip, when it overloads, the ADC output becomes
total garbage.

In other words, I don't know of any reasonable answer.  To my mind, the
ADC determines the maximum usable dynamic range.  If the strong signals
overwhelm the ADC maximum signal levels, no signals can be successfully
demodulated.

Mathematically, the overload situation might not be considered, but with
practical devices (ADC), overload is quite possible.

73,
Don W3FPR

On 11/10/2015 7:32 PM, Fred Jensen wrote:
> Question from a mathematics major [whose parents wanted him to be a EE]:
>
> In a direct-sampling receiver, how do you control the input level to
> the ADC to achieve maximum available dynamic range without clipping at
> the ADC?
>

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Re: Sherwood Receiver Test Data - K3S Added Today

Steve Ellington-2
In reply to this post by k6dgw
Fred
Well for the Flex 6000 series you keep one hand on the so called AGC-T
control. Since there is no hardware AGC you're doomed to constantly
juggling the input level.
I had one here and used the Flex Control knob to perform that function.
Using it this way brings back memories of Pre-AGC days and frequent
adjustment of the RF gain knob.
Steve N4LQ

On Tue, Nov 10, 2015 at 7:32 PM, Fred Jensen <[hidden email]> wrote:

> Question from a mathematics major [whose parents wanted him to be a EE]:
>
> In a direct-sampling receiver, how do you control the input level to the
> ADC to achieve maximum available dynamic range without clipping at the ADC?
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the Cal QSO Party 1-2 Oct 2016
> - www.cqp.org
>
> On 11/10/2015 3:58 PM, Steve Ellington wrote:
>
>> Looks like the K3S should be above the Flex because the Flex achieved 2DB
>> higher due to:
>>
>> Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."
>>
>> Congratulations K3S
>> Steve N4LQ
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
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Re: Sherwood Receiver Test Data - K3S Added Today

k6dgw
In reply to this post by Gary Gregory-2
Not heavy enough, minimum specs for boatanchor is 75 lbs.  SX-28 and
DX-100 were boatanchors.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org


On 11/10/2015 4:34 PM, Gary wrote:

> Glad I upgraded my K3 (2007) vintage, guess now mine can be termed a
> boat anchor?
>
> 73
>
> Gary
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Re: Sherwood Receiver Test Data - K3S Added Today

Elecraft mailing list
In reply to this post by k6dgw
Great results Guys.  But my K3S still won't slice bread!

73
de
George, W6GF

Sent from my iPad

> On Nov 10, 2015, at 4:32 PM, Fred Jensen <[hidden email]> wrote:
>
> Question from a mathematics major [whose parents wanted him to be a EE]:
>
> In a direct-sampling receiver, how do you control the input level to the ADC to achieve maximum available dynamic range without clipping at the ADC?
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the Cal QSO Party 1-2 Oct 2016
> - www.cqp.org
>
>> On 11/10/2015 3:58 PM, Steve Ellington wrote:
>> Looks like the K3S should be above the Flex because the Flex achieved 2DB
>> higher due to:
>>
>> Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."
>>
>> Congratulations K3S
>> Steve N4LQ
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
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Re: Sherwood Receiver Test Data - K3S Added Today

Barry K3NDM
In reply to this post by k6dgw
Fred,
     When you have a 24 bit A/D and not looking at the entire spectrum,
this should not be as big a problem as you imply, if gain distribution
is correct.  24 bits should yield a great enough dynamic range to cover
greater than ~ 95% of time; that last ~5% covers your friend next door
with a KW or that thunderstorm over head. 24 bits also allows for some
amplification to overcome the down stream noise figure that may be
greater than ambient.
     On the other hand, the Flex uses a really high speed A/D, but it is
only 16 bits, if memory serves. That architecture is far more sensitive
to gain distribution. Those who have suggested that the Flex may have a
problem with all the bits going to 1 in a stress environment may be very
correct. IMHO: With the state of the A/D art as it is, I believe
Elecraft has the better practical architecture. As soon as low noise,
high speed A/Ds become available with greater than 16 bits, my opinion
may change.

73,
Barry
K3NDM


------ Original Message ------
From: "Fred Jensen" <[hidden email]>
To: [hidden email]
Sent: 11/10/2015 7:32:56 PM
Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today

>Question from a mathematics major [whose parents wanted him to be a
>EE]:
>
>In a direct-sampling receiver, how do you control the input level to
>the ADC to achieve maximum available dynamic range without clipping at
>the ADC?
>
>73,
>
>Fred K6DGW
>- Northern California Contest Club
>- CU in the Cal QSO Party 1-2 Oct 2016
>- www.cqp.org
>
>On 11/10/2015 3:58 PM, Steve Ellington wrote:
>>Looks like the K3S should be above the Flex because the Flex achieved
>>2DB
>>higher due to:
>>
>>Footnote Y --- "This is a testing anomaly of a direct-sampling
>>receiver."
>>
>>Congratulations K3S
>>Steve N4LQ
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html
>Message delivered to [hidden email]

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Re: Sherwood Receiver Test Data - K3S Added Today

wayne burdick
Administrator
In reply to this post by Bill Breeden
Bill Breeden <[hidden email]> wrote:

> Rob Sherwood added the K3S to his Receiver Test Data page today.


Yes. We're pleased to see some excellent test results, including 106 dB of IMDDR3 at 2 kHz for both the 200- and 400-Hz filters. (The K3 came in at 104 dB for the 400-Hz filter. The 107-dB reading is within the usual +/- 1 dB lab/tech repeatability figure.)

Also worthy of note: sensitivity of -145 dBm for the new Preamp 2 on 10 meters. This preamp is also used on 12 and 6 meters.

I checked with Rob, and that blocking dynamic range number (>154 dB) is *not* a typo. He said he saw less than 3 dB phase noise degradation at 100 kHz with +19 dBm fed into the radio, and stopped at that point. I guess there's no point in melting the signal combiner :)

(By the way, Rob's K3S BDR test level of +19 dBm is exactly 10 dB *higher* than the preamp-OFF ADC clipping level of the 6700. With preamp ON, it would clip at an estimated -11 dBm.)

73,
Wayne
N6KR



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Re: Sherwood Receiver Test Data - K3S Added Today

Joe Subich, W4TV-4
In reply to this post by k6dgw

> In a direct-sampling receiver, how do you control the input level to
> the ADC to achieve maximum available dynamic range without clipping
> at theADC?

It's a matter of gain/attenuation before the ADC.  If, for example,
one looks at the Flex-6700 they have four steps of preamplifier gain:
0, 10, 20 and 30 dB.  The best MDS and dynamic range is with 30 dB of
gain as long as one keeps the *total input signal* below the ADC
crapping threshold.  If the total input signal exceeds the ADC crap
threshold one needs to reduce the front end gain to bring total signal
levels below the overload point but that drops the weak signals below
the noise floor (typically on a dB for dB basis as preamp gain is
reduced).

Digital processing gain (decimation) helps with the dynamic range to
some degree - e.g. dynamic range is better than the simple number of
bits - but it can't do a thing when the ADC overflows and generates
garbage data.

73,

   ... Joe, W4TV


On 11/10/2015 7:32 PM, Fred Jensen wrote:

> Question from a mathematics major [whose parents wanted him to be a EE]:
>
> In a direct-sampling receiver, how do you control the input level to the
> ADC to achieve maximum available dynamic range without clipping at the ADC?
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the Cal QSO Party 1-2 Oct 2016
> - www.cqp.org
>
> On 11/10/2015 3:58 PM, Steve Ellington wrote:
>> Looks like the K3S should be above the Flex because the Flex achieved 2DB
>> higher due to:
>>
>> Footnote Y --- "This is a testing anomaly of a direct-sampling receiver."
>>
>> Congratulations K3S
>> Steve N4LQ
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
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Re: Sherwood Receiver Test Data - K3S Added Today

k6dgw
In reply to this post by Barry K3NDM
OK.  Remembering that I'm the one who disappointed Mom and Dad when I
got A's in Math and B's and C's in EE, and finally transferred to the
Math Dept ...

I didn't want to imply it was a problem, it was just a question.  First
off, I believe a direct-sampling SDR is one that essentially does
nothing to the entire RF envelope being received except maybe bandpass
limit it to the ham band of interest.  No guarantee that's correct, and
if it isn't, you might as well delete this now.

But if it is what direct-sample means, and since the RF envelope is both
+ and -, in an 8-bit ADC, 127 would be zero, 255 [all 1's] would be the
maximum along with all 0's for the negative parts.  If the RF envelope
is allowed to go above the value that digitizes to all 1's, it will
still digitize to all 1's and it's excursions above all 1's are lost
[i.e. clipped].  In my experience as a ham, this is rarely if ever a
good thing.

OTOH, you want as much dynamic range as possible, so you want the
strongest input to the ADC be at the all-1's level so the parts of the
envelope below that level will digitize to something other than zero
[127 in my 8-bit example].  Any signals below that level will digitize
to 127 and you'll never hear them.

If the gain of the RF stage(s), and I'm assuming there is at least one
RF stage, is such that the maximum of the RF envelope is below the
clipping point, then it seems to me that signals you might have heard
won't be heard because they never got digitized.

My question was [and is], do direct sampling receivers employ some sort
of AGC to keep the max RF envelope at the clipping point?  If the answer
is "yes", I have a second question in the wings waiting to be asked.

Mom and Dad never recovered from their mathematician's defection from
EE, despite having been a wireless addict since age 12.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org


On 11/10/2015 5:06 PM, Barry LaZar wrote:

> Fred,
>      When you have a 24 bit A/D and not looking at the entire spectrum,
> this should not be as big a problem as you imply, if gain distribution
> is correct.  24 bits should yield a great enough dynamic range to cover
> greater than ~ 95% of time; that last ~5% covers your friend next door
> with a KW or that thunderstorm over head. 24 bits also allows for some
> amplification to overcome the down stream noise figure that may be
> greater than ambient.
>      On the other hand, the Flex uses a really high speed A/D, but it is
> only 16 bits, if memory serves. That architecture is far more sensitive
> to gain distribution. Those who have suggested that the Flex may have a
> problem with all the bits going to 1 in a stress environment may be very
> correct. IMHO: With the state of the A/D art as it is, I believe
> Elecraft has the better practical architecture. As soon as low noise,
> high speed A/Ds become available with greater than 16 bits, my opinion
> may change.
>
> 73,
> Barry
> K3NDM
>
>
> ------ Original Message ------
> From: "Fred Jensen" <[hidden email]>
> To: [hidden email]
> Sent: 11/10/2015 7:32:56 PM
> Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today
>
>> Question from a mathematics major [whose parents wanted him to be a EE]:
>>
>> In a direct-sampling receiver, how do you control the input level to
>> the ADC to achieve maximum available dynamic range without clipping at
>> the ADC?
>>
>> 73,
>>
>> Fred K6DGW
>> - Northern California Contest Club
>> - CU in the Cal QSO Party 1-2 Oct 2016
>> - www.cqp.org
>>
>> On 11/10/2015 3:58 PM, Steve Ellington wrote:
>>> Looks like the K3S should be above the Flex because the Flex achieved
>>> 2DB
>>> higher due to:
>>>
>>> Footnote Y --- "This is a testing anomaly of a direct-sampling
>>> receiver."
>>>
>>> Congratulations K3S
>>> Steve N4LQ
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2016.0.7227 / Virus Database: 4460/10976 - Release Date: 11/10/15
>
>
>
>

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Re: Sherwood Receiver Test Data - K3S Added Today

Steve Ellington-2
Part of the problem here is that Flex won't release the schematic to the
6000 series so who knows?
I suspect that the AGC-T (Agc  threshold) control actually adjust the input
level to the ADC....somehow.
This control is manual and must be fiddled with per-band as conditions
change. Strong signals will sound distorted and you must manually
compensate often.
N4LQ

On Tue, Nov 10, 2015 at 8:42 PM, Fred Jensen <[hidden email]> wrote:

> OK.  Remembering that I'm the one who disappointed Mom and Dad when I got
> A's in Math and B's and C's in EE, and finally transferred to the Math Dept
> ...
>
> I didn't want to imply it was a problem, it was just a question.  First
> off, I believe a direct-sampling SDR is one that essentially does nothing
> to the entire RF envelope being received except maybe bandpass limit it to
> the ham band of interest.  No guarantee that's correct, and if it isn't,
> you might as well delete this now.
>
> But if it is what direct-sample means, and since the RF envelope is both +
> and -, in an 8-bit ADC, 127 would be zero, 255 [all 1's] would be the
> maximum along with all 0's for the negative parts.  If the RF envelope is
> allowed to go above the value that digitizes to all 1's, it will still
> digitize to all 1's and it's excursions above all 1's are lost [i.e.
> clipped].  In my experience as a ham, this is rarely if ever a good thing.
>
> OTOH, you want as much dynamic range as possible, so you want the
> strongest input to the ADC be at the all-1's level so the parts of the
> envelope below that level will digitize to something other than zero [127
> in my 8-bit example].  Any signals below that level will digitize to 127
> and you'll never hear them.
>
> If the gain of the RF stage(s), and I'm assuming there is at least one RF
> stage, is such that the maximum of the RF envelope is below the clipping
> point, then it seems to me that signals you might have heard won't be heard
> because they never got digitized.
>
> My question was [and is], do direct sampling receivers employ some sort of
> AGC to keep the max RF envelope at the clipping point?  If the answer is
> "yes", I have a second question in the wings waiting to be asked.
>
> Mom and Dad never recovered from their mathematician's defection from EE,
> despite having been a wireless addict since age 12.
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the Cal QSO Party 1-2 Oct 2016
> - www.cqp.org
>
>
> On 11/10/2015 5:06 PM, Barry LaZar wrote:
>
>> Fred,
>>      When you have a 24 bit A/D and not looking at the entire spectrum,
>> this should not be as big a problem as you imply, if gain distribution
>> is correct.  24 bits should yield a great enough dynamic range to cover
>> greater than ~ 95% of time; that last ~5% covers your friend next door
>> with a KW or that thunderstorm over head. 24 bits also allows for some
>> amplification to overcome the down stream noise figure that may be
>> greater than ambient.
>>      On the other hand, the Flex uses a really high speed A/D, but it is
>> only 16 bits, if memory serves. That architecture is far more sensitive
>> to gain distribution. Those who have suggested that the Flex may have a
>> problem with all the bits going to 1 in a stress environment may be very
>> correct. IMHO: With the state of the A/D art as it is, I believe
>> Elecraft has the better practical architecture. As soon as low noise,
>> high speed A/Ds become available with greater than 16 bits, my opinion
>> may change.
>>
>> 73,
>> Barry
>> K3NDM
>>
>>
>> ------ Original Message ------
>> From: "Fred Jensen" <[hidden email]>
>> To: [hidden email]
>> Sent: 11/10/2015 7:32:56 PM
>> Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today
>>
>> Question from a mathematics major [whose parents wanted him to be a EE]:
>>>
>>> In a direct-sampling receiver, how do you control the input level to
>>> the ADC to achieve maximum available dynamic range without clipping at
>>> the ADC?
>>>
>>> 73,
>>>
>>> Fred K6DGW
>>> - Northern California Contest Club
>>> - CU in the Cal QSO Party 1-2 Oct 2016
>>> - www.cqp.org
>>>
>>> On 11/10/2015 3:58 PM, Steve Ellington wrote:
>>>
>>>> Looks like the K3S should be above the Flex because the Flex achieved
>>>> 2DB
>>>> higher due to:
>>>>
>>>> Footnote Y --- "This is a testing anomaly of a direct-sampling
>>>> receiver."
>>>>
>>>> Congratulations K3S
>>>> Steve N4LQ
>>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2016.0.7227 / Virus Database: 4460/10976 - Release Date: 11/10/15
>>
>>
>>
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
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Re: Sherwood Receiver Test Data - K3S Added Today

Elecraft mailing list
In reply to this post by wayne burdick
Yes, I saw that -145 truly outstanding. Now, if it could only creat some sun spots and open 10 meters.

73
de
George, W6GF

Sent from my iPad

> On Nov 10, 2015, at 5:10 PM, Wayne Burdick <[hidden email]> wrote:
>
> Bill Breeden <[hidden email]> wrote:
>
>> Rob Sherwood added the K3S to his Receiver Test Data page today.
>
>
> Yes. We're pleased to see some excellent test results, including 106 dB of IMDDR3 at 2 kHz for both the 200- and 400-Hz filters. (The K3 came in at 104 dB for the 400-Hz filter. The 107-dB reading is within the usual +/- 1 dB lab/tech repeatability figure.)
>
> Also worthy of note: sensitivity of -145 dBm for the new Preamp 2 on 10 meters. This preamp is also used on 12 and 6 meters.
>
> I checked with Rob, and that blocking dynamic range number (>154 dB) is *not* a typo. He said he saw less than 3 dB phase noise degradation at 100 kHz with +19 dBm fed into the radio, and stopped at that point. I guess there's no point in melting the signal combiner :)
>
> (By the way, Rob's K3S BDR test level of +19 dBm is exactly 10 dB *higher* than the preamp-OFF ADC clipping level of the 6700. With preamp ON, it would clip at an estimated -11 dBm.)
>
> 73,
> Wayne
> N6KR
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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Re: Sherwood Receiver Test Data - K3S Added Today

Barry K3NDM
In reply to this post by Steve Ellington-2
Steve,
     Not having the schematic of the Flex isn't as important as knowing
they are using a 16 bit A/D. In a perfect world, the rule of thumb is
6db/bit, 96 db may be accounted for. However, an A/D that can cover all
the way to 2 meters has to be very fast > 296 msp, if you believe
Nyquist. If you apply hardware AGC in any form, it is reflected across
the entire spectrum. And to add further insult, high speed A/Ds have
noise figures great enough to mask ambient noise at mid and above HF.
That means you need to add a low noise amplifier ahead of the A/D with
enough gain to overcome system noise, and that will start to bite into
those 16 bits by a function of the gain of the amplifier. You can do
some creative things like use tapered gain amplifiers that have a
reverse taper so that max gain is at the high end of the spectrum;
Typically signals and noise are greater at the lower end of HF even if
SNR appear to be greater at the high end.

     The use of a 24 bit A/D allows for using a simpler approach and yet
maintain a high dynamic range.  It also disallows using A/Ds that can
cover the entire spectrum as they don't yet exist.

     Unlike math and physics, EEs are more artists than scientists. I
suspect the discussions at Elecraft over the architectures would have
been very interesting. There are advantages and disadvantages to direct
sampling and to the hetrodyne SDR's. Which is better? It's a function of
how you want to handle the requirement set which may impact price. Why
do I call engineers artists? The sciences are absolute and engineers
have to craft a solution that accounts for the compromises, and few
engineers always agree on the very same solution. One may like red and
another may like blue so the creation comes out as a work of art. The
bottom line is that the chosen implementations of Elecraft radios are
Gee Whiz and exceed what the casual user needs and appears to be the
best for contesting. That last bit is my opinion and I'm sticking with
it.

     Just for the record, I use a KX3. It is lower on Sherwood's
rankings, but I think it is the best overall radio out there. It
satisfies a greater number of my requirements. And, that is how I
colored my solution.  ;-)


73,
Barry
K3NDM


------ Original Message ------
From: "Steve Ellington" <[hidden email]>
To: [hidden email]
Cc: "Elecraft Reflector" <[hidden email]>
Sent: 11/10/2015 8:51:16 PM
Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today

>Part of the problem here is that Flex won't release the schematic to
>the
>6000 series so who knows?
>I suspect that the AGC-T (Agc  threshold) control actually adjust the
>input
>level to the ADC....somehow.
>This control is manual and must be fiddled with per-band as conditions
>change. Strong signals will sound distorted and you must manually
>compensate often.
>N4LQ
>
>On Tue, Nov 10, 2015 at 8:42 PM, Fred Jensen <[hidden email]>
>wrote:
>
>>  OK.  Remembering that I'm the one who disappointed Mom and Dad when I
>>got
>>  A's in Math and B's and C's in EE, and finally transferred to the
>>Math Dept
>>  ...
>>
>>  I didn't want to imply it was a problem, it was just a question.  
>>First
>>  off, I believe a direct-sampling SDR is one that essentially does
>>nothing
>>  to the entire RF envelope being received except maybe bandpass limit
>>it to
>>  the ham band of interest.  No guarantee that's correct, and if it
>>isn't,
>>  you might as well delete this now.
>>
>>  But if it is what direct-sample means, and since the RF envelope is
>>both +
>>  and -, in an 8-bit ADC, 127 would be zero, 255 [all 1's] would be the
>>  maximum along with all 0's for the negative parts.  If the RF
>>envelope is
>>  allowed to go above the value that digitizes to all 1's, it will
>>still
>>  digitize to all 1's and it's excursions above all 1's are lost [i.e.
>>  clipped].  In my experience as a ham, this is rarely if ever a good
>>thing.
>>
>>  OTOH, you want as much dynamic range as possible, so you want the
>>  strongest input to the ADC be at the all-1's level so the parts of
>>the
>>  envelope below that level will digitize to something other than zero
>>[127
>>  in my 8-bit example].  Any signals below that level will digitize to
>>127
>>  and you'll never hear them.
>>
>>  If the gain of the RF stage(s), and I'm assuming there is at least
>>one RF
>>  stage, is such that the maximum of the RF envelope is below the
>>clipping
>>  point, then it seems to me that signals you might have heard won't be
>>heard
>>  because they never got digitized.
>>
>>  My question was [and is], do direct sampling receivers employ some
>>sort of
>>  AGC to keep the max RF envelope at the clipping point?  If the answer
>>is
>>  "yes", I have a second question in the wings waiting to be asked.
>>
>>  Mom and Dad never recovered from their mathematician's defection from
>>EE,
>>  despite having been a wireless addict since age 12.
>>
>>  73,
>>
>>  Fred K6DGW
>>  - Northern California Contest Club
>>  - CU in the Cal QSO Party 1-2 Oct 2016
>>  - www.cqp.org
>>
>>
>>  On 11/10/2015 5:06 PM, Barry LaZar wrote:
>>
>>>  Fred,
>>>       When you have a 24 bit A/D and not looking at the entire
>>>spectrum,
>>>  this should not be as big a problem as you imply, if gain
>>>distribution
>>>  is correct.  24 bits should yield a great enough dynamic range to
>>>cover
>>>  greater than ~ 95% of time; that last ~5% covers your friend next
>>>door
>>>  with a KW or that thunderstorm over head. 24 bits also allows for
>>>some
>>>  amplification to overcome the down stream noise figure that may be
>>>  greater than ambient.
>>>       On the other hand, the Flex uses a really high speed A/D, but
>>>it is
>>>  only 16 bits, if memory serves. That architecture is far more
>>>sensitive
>>>  to gain distribution. Those who have suggested that the Flex may
>>>have a
>>>  problem with all the bits going to 1 in a stress environment may be
>>>very
>>>  correct. IMHO: With the state of the A/D art as it is, I believe
>>>  Elecraft has the better practical architecture. As soon as low
>>>noise,
>>>  high speed A/Ds become available with greater than 16 bits, my
>>>opinion
>>>  may change.
>>>
>>>  73,
>>>  Barry
>>>  K3NDM
>>>
>>>
>>>  ------ Original Message ------
>>>  From: "Fred Jensen" <[hidden email]>
>>>  To: [hidden email]
>>>  Sent: 11/10/2015 7:32:56 PM
>>>  Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added
>>>Today
>>>
>>>  Question from a mathematics major [whose parents wanted him to be a
>>>EE]:
>>>>
>>>>  In a direct-sampling receiver, how do you control the input level
>>>>to
>>>>  the ADC to achieve maximum available dynamic range without clipping
>>>>at
>>>>  the ADC?
>>>>
>>>>  73,
>>>>
>>>>  Fred K6DGW
>>>>  - Northern California Contest Club
>>>>  - CU in the Cal QSO Party 1-2 Oct 2016
>>>>  - www.cqp.org
>>>>
>>>>  On 11/10/2015 3:58 PM, Steve Ellington wrote:
>>>>
>>>>>  Looks like the K3S should be above the Flex because the Flex
>>>>>achieved
>>>>>  2DB
>>>>>  higher due to:
>>>>>
>>>>>  Footnote Y --- "This is a testing anomaly of a direct-sampling
>>>>>  receiver."
>>>>>
>>>>>  Congratulations K3S
>>>>>  Steve N4LQ
>>>>>
>>>>
>>>>  ______________________________________________________________
>>>>  Elecraft mailing list
>>>>  Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>  Help: http://mailman.qth.net/mmfaq.htm
>>>>  Post: mailto:[hidden email]
>>>>
>>>>  This list hosted by: http://www.qsl.net
>>>>  Please help support this email list: http://www.qsl.net/donate.html
>>>>  Message delivered to [hidden email]
>>>>
>>>
>>>
>>>  -----
>>>  No virus found in this message.
>>>  Checked by AVG - www.avg.com
>>>  Version: 2016.0.7227 / Virus Database: 4460/10976 - Release Date:
>>>11/10/15
>>>
>>>
>>>
>>>
>>>
>>  ______________________________________________________________
>>  Elecraft mailing list
>>  Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>  Help: http://mailman.qth.net/mmfaq.htm
>>  Post: mailto:[hidden email]
>>
>>  This list hosted by: http://www.qsl.net
>>  Please help support this email list: http://www.qsl.net/donate.html
>>  Message delivered to [hidden email]
>>
>______________________________________________________________
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Re: Sherwood Receiver Test Data - K3S Added Today

Bob McGraw - K4TAX
In reply to this post by Don Wilhelm-4
One thing which is seriously missing from the definition and that is a
boat anchor must have a place to tie a rope which then becomes an anchor
line.  With no place to tie a rope, the item  is merely ballast.   There
are some of the new radios that fall into both of these categories and
thus should be used accordingly.

73
Bob, K4TAX

On 11/10/2015 6:43 PM, Don Wilhelm wrote:
> Gary,
>
> By definition, a boat anchor has vacuum tubes that glow, and have to
> be more than 40 years old (my definition).
> Ohhh, and they need to include a power transformer which gives them
> enough weight to allow them to sink to the bottom of the lake.


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Re: Sherwood Receiver Test Data - K3S Added Today

Gary Gregory-2
Bob,

Adding a rope might cause me to suspend myself unintentionally and that could mean an unexpected trip to the human body shop.

Best I just leave well enough alone.

Seriously though a couple of Yaesu boat anchor operators local to me chat on 40m everyday, one day soon I hope they can agree on what frequency they wish to transmit on. I have just about passed the use by date on my RIT knob.

73

Gary

-----Original Message-----
From: "Bob McGraw - K4TAX" <[hidden email]>
Sent: ‎11/‎11/‎2015 2:05 PM
To: "[hidden email]" <[hidden email]>
Subject: Re: [Elecraft] Sherwood Receiver Test Data - K3S Added Today

One thing which is seriously missing from the definition and that is a
boat anchor must have a place to tie a rope which then becomes an anchor
line.  With no place to tie a rope, the item  is merely ballast.   There
are some of the new radios that fall into both of these categories and
thus should be used accordingly.

73
Bob, K4TAX

On 11/10/2015 6:43 PM, Don Wilhelm wrote:
> Gary,
>
> By definition, a boat anchor has vacuum tubes that glow, and have to
> be more than 40 years old (my definition).
> Ohhh, and they need to include a power transformer which gives them
> enough weight to allow them to sink to the bottom of the lake.


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