Re: [Elecraft] [K3] AGC

[Darwin, Keith]

Since AGC automatically turns down the gain when there is a big signal,
I'd expect that it would make things quiet.  Basically, it adjusts the
gain to equalize all signals.  Band noise, weak signals, strong signals
- all are rendered at the same volume level as they come out the
speaker.  Turn AGC off and the quiet stuff remains quiet while the loud
stuff gets much louder.  Overall S/N ratio goes way up.

I run my rig with a combination of AGC on/off.  I turn AGC on (to squash
any loud peaks) then back RF gain down until the noise background gets
weak.  Now I have a higher average S/N ratio but still have the
ear-protection benefits of AGC.

- Keith N1AS -
- K3 711 -

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of W2XB
Sent: Friday, March 06, 2009 7:43 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] [K3] AGC


Hello Folks,
 Just talking to a friend that has a K3 also and he was asking why the
signal gets louder with less noise when you turn off the "AGC" ? I
turned off tha agc when working a weak DX station, and he was right.
Made the copy easier and much louder. What is the technical reason for
this?

Don..w2xb
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Re: [Elecraft] [K3] AGC

[Don Wilhelm]

Kieth is correct if the AGC parameters are set high, particularly the 
slope - that tries to make everything the same volume.  If you can 
recall tuning an AM radio between stations, the noise level between 
stations gets louder because there is no signal to hold the AGC active, 
and the AGC is quite aggressive.

I did not like the behavior of the AGC with the default settings, I 
liked the AGC behavior on my K2.  After seeing the curves produced by 
Jack Smith (Clifton Labs), I changed my AGC parameters to more closely 
emulate the K2.
AGC PLS off
AGC SLP 002
AGC THR 008
AGC-F 140
AGC-S 010

I like my K3 AGC now - weak signals sound weaker than strong ones and 
the noise level does not rise as much.  Your preferences may vary.

73,
Don W3FPR


Darwin, Keith wrote:
> Since AGC automatically turns down the gain when there is a big signal,
> I'd expect that it would make things quiet.  Basically, it adjusts the
> gain to equalize all signals.  Band noise, weak signals, strong signals
> - all are rendered at the same volume level as they come out the
> speaker.  Turn AGC off and the quiet stuff remains quiet while the loud
> stuff gets much louder.  Overall S/N ratio goes way up.
>
> I run my rig with a combination of AGC on/off.  I turn AGC on (to squash
> any loud peaks) then back RF gain down until the noise background gets
> weak.  Now I have a higher average S/N ratio but still have the
> ear-protection benefits of AGC.
>
> - Keith N1AS -
> - K3 711 -
>
> -Original Message-
> From: elecraft-boun...@mailman.qth.net
> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of W2XB
> Sent: Friday, March 06, 2009 7:43 AM
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] [K3] AGC
>
>
> Hello Folks,
>  Just talking to a friend that has a K3 also and he was asking why the
> signal gets louder with less noise when you turn off the "AGC" ? I
> turned off tha agc when working a weak DX station, and he was right.
> Made the copy easier and much louder. What is the technical reason for
> this?
>
> Don..w2xb
> --
> View this message in context:
> http://n2.nabble.com/AGC-tp2435434p2435434.html
> Sent from the [K3] mailing list archive at Nabble.com.
>
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> 07:54:00
>
>   
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Re: [Elecraft] [K3] AGC

[W2XB]

Thanks for the reply Keith,

 Makes sense. 



Don...w2xb 

 

---Original Message---

 

From: Darwin, Keith (via Nabble)

Date: 03/06/09 07:56:25

To: W2XB

Subject: Re: AGC

 

Since AGC automatically turns down the gain when there is a big signal, 

I'd expect that it would make things quiet.  Basically, it adjusts the 

gain to equalize all signals.  Band noise, weak signals, strong signals 

- all are rendered at the same volume level as they come out the 

speaker.  Turn AGC off and the quiet stuff remains quiet while the loud 

stuff gets much louder.  Overall S/N ratio goes way up. 



I run my rig with a combination of AGC on/off.  I turn AGC on (to squash 

any loud peaks) then back RF gain down until the noise background gets 

weak.  Now I have a higher average S/N ratio but still have the 

ear-protection benefits of AGC. 



- Keith N1AS - 

- K3 711 - 



-Original Message- 

From: elecraft-boun...@... 

[mailto:elecraft-boun...@...] On Behalf Of W2XB 

Sent: Friday, March 06, 2009 7:43 AM 

To: elecr...@... 

Subject: [Elecraft] [K3] AGC 





Hello Folks, 

 Just talking to a friend that has a K3 also and he was asking why the 

signal gets louder with less noise when you turn off the "AGC" ? I 

turned off tha agc when working a weak DX station, and he was right. 

Made the copy easier and much louder. What is the technical reason for 

this? 



Don..w2xb 

-- 

View this message in context: 

http://n2.nabble.com/AGC-tp2435434p2435434.html

Sent from the [K3] mailing list archive at Nabble.com. 



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This email is a reply to your post @ http://n2.nabble
com/AGC-tp2435434p2435493.html

You can reply by email or by visting the link above.







 
 
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Re: [Elecraft] [K3] AGC

[Ron NA9F]

Don thanks for the following info. These settings really gets rid of the
noise
and signals are there. I changed my settings.

Ron NA9F

Don's stated AGC settings:

AGC PLS off
AGC SLP 002
AGC THR 008
AGC-F 140
AGC-S 010

I like my K3 AGC now - weak signals sound weaker than strong ones and 
the noise level does not rise as much.  Your preferences may vary.

73,
Don W3FPR



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Re: [Elecraft] [K3] AGC

[Ralph Tyrrell]

Don:
Your setting are so different from mine.
I tried yours, and now I have a brand new K3.

Thank you.

73, W1TF, K3 #696 , K1 # 1423, gets used once in a while.


--- On Fri, 3/6/09, Don Wilhelm  wrote:

> From: Don Wilhelm 
> Subject: Re: [Elecraft] [K3]  AGC
> To: elecraft@mailman.qth.net
> Date: Friday, March 6, 2009, 8:22 AM
> Kieth is correct if the AGC parameters are set high,
> particularly the 
> slope - that tries to make everything the same volume.  If
> you can 
> recall tuning an AM radio between stations, the noise level
> between 
> stations gets louder because there is no signal to hold the
> AGC active, 
> and the AGC is quite aggressive.
> 
> I did not like the behavior of the AGC with the default
> settings, I 
> liked the AGC behavior on my K2.  After seeing the curves
> produced by 
> Jack Smith (Clifton Labs), I changed my AGC parameters to
> more closely 
> emulate the K2.
> AGC PLS off
> AGC SLP 002
> AGC THR 008
> AGC-F 140
> AGC-S 010
> 
> I like my K3 AGC now - weak signals sound weaker than
> strong ones and 
> the noise level does not rise as much.  Your preferences
> may vary.
> 
> 73,
> Don W3FPR



  
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Re: [Elecraft] [K3] AGC

[Alexandr Kobranov]

Stan,
it is very useful to "program" AGC slope settings to PF1 or PF2 key to 
have instant access from panel by one key to this setting.

(I have AGC slope assigned to PF1 and TECH mode ON to PF2)

73!
Lexa, ok1dst
K3/10 #727


Stan Rife napsal(a):
 Thanks, I appreciate the help. I guess I have not gone through the 
manual enough times to find this. Didn't know it was adjustable.


Stan
W5EWA


Lyle Johnson wrote:
   I've noticed on strong signals that the audio gets really loud and 
I have to reach for the volume control. Isn't the AGC supposed to 
keep that from happening? Has anyone else noticed this?


The AGC SLP parameter in the CONFIG menu allows you to adjust the AGC 
out vs input ratio.


73,

Lyle KK7P




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Re: [Elecraft] [K3] AGC

[Bob Cunnings]

Have you tried adjusting the CONFIG:AGC SLP parameter? I've set mine
to the maximum value, 15, for flattest AGC slope.

Bob NW8L

On Mon, Jul 7, 2008 at 8:13 AM, S Sacco <[EMAIL PROTECTED]> wrote:
> OK, now that I'm slowly getting my station rebuild to the point where
> I'm operating my K3 on a regular basis, I'm noticing that the AGC
> seems to be kind of sub-optimal.  There are large differences in audio
> volume when receiving different strength signals.   I have not been
> directly comparing the K3 to another receiver, but it keep surprising
> me (in a bad way).  On a couple of occasions, I had to rip off my
> headphones, because it was faster than reaching for the volume
> control.
>
> I seem to remember this being somewhat of an issue with earlier
> firmware versions, but I'm running 2.13 at this time.
>
> Is anyone else having this issue?
>
> 73,
> Steve NN4X
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RE: [Elecraft] [K3] AGC

[Bud Semon N7CW]

I have the CONFIG: AGC SLP parameter set to 15 also and I think it is not
aggressive enough - that is, the volume difference is too large between weak
and strong signals.

73, Bud N7CW

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Bob Cunnings
Sent: Monday, July 07, 2008 7:18 AM
To: S Sacco
Cc: Elecraft Reflector
Subject: Re: [Elecraft] [K3] AGC

Have you tried adjusting the CONFIG:AGC SLP parameter? I've set mine
to the maximum value, 15, for flattest AGC slope.

Bob NW8L

On Mon, Jul 7, 2008 at 8:13 AM, S Sacco <[EMAIL PROTECTED]> wrote:
> OK, now that I'm slowly getting my station rebuild to the point where
> I'm operating my K3 on a regular basis, I'm noticing that the AGC
> seems to be kind of sub-optimal.  There are large differences in audio
> volume when receiving different strength signals.   I have not been
> directly comparing the K3 to another receiver, but it keep surprising
> me (in a bad way).  On a couple of occasions, I had to rip off my
> headphones, because it was faster than reaching for the volume
> control.
>
> I seem to remember this being somewhat of an issue with earlier
> firmware versions, but I'm running 2.13 at this time.
>
> Is anyone else having this issue?
>
> 73,
> Steve NN4X
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Re: [Elecraft] [K3] AGC

[Jim Cox]

I agree, I also have mine set at 15 and there does seem to be a large 
difference in the audio level of weak and loud stations...  Jim K4JAF



- Original Message - 
From: "Bud Semon N7CW" <[EMAIL PROTECTED]>

To: 
Sent: Monday, July 07, 2008 9:26 AM
Subject: RE: [Elecraft] [K3] AGC



I have the CONFIG: AGC SLP parameter set to 15 also and I think it is not
aggressive enough - that is, the volume difference is too large between 
weak

and strong signals.

73, Bud N7CW

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Bob Cunnings
Sent: Monday, July 07, 2008 7:18 AM
To: S Sacco
Cc: Elecraft Reflector
Subject: Re: [Elecraft] [K3] AGC

Have you tried adjusting the CONFIG:AGC SLP parameter? I've set mine
to the maximum value, 15, for flattest AGC slope.

Bob NW8L

On Mon, Jul 7, 2008 at 8:13 AM, S Sacco <[EMAIL PROTECTED]> wrote:

OK, now that I'm slowly getting my station rebuild to the point where
I'm operating my K3 on a regular basis, I'm noticing that the AGC
seems to be kind of sub-optimal.  There are large differences in audio
volume when receiving different strength signals.   I have not been
directly comparing the K3 to another receiver, but it keep surprising
me (in a bad way).  On a couple of occasions, I had to rip off my
headphones, because it was faster than reaching for the volume
control.

I seem to remember this being somewhat of an issue with earlier
firmware versions, but I'm running 2.13 at this time.

Is anyone else having this issue?

73,
Steve NN4X
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Re: [Elecraft] [K3] AGC

[Lyle Johnson]

... There are large differences in audio
volume when receiving different strength signals.  


There are two AGC  parameters that should help.

1) AGC THR

This sets the signal strength which must occur before AGC is activated. 
 It is defaulted to the several microvolts range.  If you are listening 
on a quiet band with a gain turned up, you might have 20 or 30 dB of 
signal range before AGC starts.  Set AGC THR to a lower value.  Based on 
your comments, I suggest a value of 1 or perhaps 2.


CONFIG:AGC THR 001

(default is 5)

2) AGC SLP

Once AGC is activated, this determines how much louder strong signals 
may sound than signals just at the AGC threshold.  15 will really 
flatten the response.


CONFIG:AGC SLP 015

(default is 10)

I suspect if you adjust both of these parameters - and AGC is ON! - you 
will be happier with the K3 in your particular operating environment.


73,

Lyle KK7P


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Re: [Elecraft] [K3] AGC

[Lyle Johnson]

CONFIG:AGC THR 001

(default is 5)


Sorry, I just checked and I see 002 is the lowest allowed value in the 
present firmware release.


73,

Lyle KK7P

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Re: [Elecraft] [K3] AGC

[Tom Childers, N5GE]

On Mon, 7 Jul 2008 09:55:58 -0500, "Jim Cox" <[EMAIL PROTECTED]> wrote:

>I agree, I also have mine set at 15 and there does seem to be a large 
>difference in the audio level of weak and loud stations...  Jim K4JAF
>
>
>- Original Message - 
>From: "Bud Semon N7CW" <[EMAIL PROTECTED]>
>To: 
>Sent: Monday, July 07, 2008 9:26 AM
>Subject: RE: [Elecraft] [K3] AGC
>
>
>>I have the CONFIG: AGC SLP parameter set to 15 also and I think it is not
>> aggressive enough - that is, the volume difference is too large between 
>> weak
>> and strong signals.
>>
>> 73, Bud N7CW
>>
[snip]

At the setting of 15 it sounds about the same as other rigs I've owned over the
years.  I prefer a setting of 12 because I like for the bigger signals to sound
louder.

Tom, N5GE - SWOT 3537 - Grid EM12jq

"Those who would give up 
Essential Liberty to 
purchase a little Temporary 
Safety deserve neither 
Liberty nor Safety" 

An excerpt from a letter 
written in 1755 from the 
Assembly to the Governor 
of Pennsylvania.

Support the entire Constitution, not 
just the parts you like.

http://www.n5ge.com
http://www.eQSL.cc/Member.cfm?N5GE

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Re: [Elecraft] [K3] AGC

[Lyle Johnson]

I have the CONFIG: AGC SLP parameter set to 15 also and I think it is not
aggressive enough - that is, the volume difference is too large 
between weak and strong signals.


I just measured it.  From a signal at the AGC threshold (-104 dBm if AGC 
THR is set to 005) to a signal 100 dB stronger, the audio output varies 
less than 0.1 dB.  It's hard to get much flatter!


I think the sumptom you are experiencing is not related to flatness, but 
to threshold.


If you set AGC THR from 005 (default) to 002 (the smallest allowed value 
at present) the threshold will drop from about -104 dBm (1.4 uV or so) 
to about -112 dBm (0.5 uV or so).  This will take about 8 dBV (or 16 dB 
in terms of power your ears hear) off the maximum level you'll hear at 
any particular AF GAIN setting as compared to the noise floor of the radio.


73,

Lyle KK7P


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Re: [Elecraft] [K3] AGC

[S Sacco]

Thanks, Lyle -

I've made those changes, and will see how they work.

Appreciate the help!!

73,
Steve NN4X


On Mon, Jul 7, 2008 at 11:08 AM, Lyle Johnson <[EMAIL PROTECTED]> wrote:
>> ... There are large differences in audio
>> volume when receiving different strength signals.
>
> There are two AGC  parameters that should help.
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RE: [Elecraft] [K3] AGC

[Darwin, Keith]

Steve, please report back with the results of your change.

I have my AGC slope set to 3 or 4 IIRC.  Anything more than that and the
rig just sounds flat with noise & signals all being the same level, just
like all the rigs that I've owned before.

- Keith N1AS -
- K3 711 - 

-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of S Sacco

Thanks, Lyle -

I've made those changes, and will see how they work.

Appreciate the help!!

73,
Steve NN4X
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Re: [Elecraft] K3 AGC

[Ian J Maude]

Dave G4AON wrote:

Ian

What settings have you got for the slope (AGC SLP)? Higher values than 
the default of 10 will give a flatter AGC response. Mine is currently 
set to 10...
Not altered it from default Dave.  Mine is at 10 currently.  What would 
be the result of changing it to 12 or more?


Ian

--

Ian J Maude, G0VGS
SysOp GB7MBC DX Cluster
Member RSGB, GQRP
K2 #4044 |K3 #455

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Re: [Elecraft] K3 AGC

[Barry N1EU]

Ian G0VGS wrote:
> 
> I feel the AGC could be better on the K3.  I notice as band conditions 
> change and a station comes up (especially at or over s9+20) I have to 
> dash for the volume control.  Has anyone else noticed this?  I have mine 
> set on slow but I feel it could be better.
> 

Ian, try this experiment.  Change your AGC Slope to 15.  Set RF Gain to
maximum with preamp on.  Tune in a very strong signal and adjust AF Gain to
your maximum comfortable listening level.  From now on, don't touch your AF
Gain and just vary RF Gain and preamp depending on band noise and signal
levels.

With Heil Proset headphones, my AF Gain stays at 9 o'clock (1/4 way up) and
my RF Gain varies from 50-100%.  Most of the time, my AGC Slope stays at 15.

73,
Barry N1EU
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Re: [Elecraft] K3 AGC?

[Lyle Johnson]

I see AGC-S on the display.  I assume that there is also AGC-F and
AGC-off, but are there any other tinkering options for the AGC?


AGC Fast and AGS Slow can be toggled by a TAP of the AGC button on the 
front panel.  HOLD that button and you get AGC OFF (or ON if it was 
already OFF).


In the menu, you can set the following parameters for AGC:

Attack time, Hold (Hang) time, Decay rate (in dB/sec for Fast and Slow), 
Threshold, and Slope.  Slope sets the compression you get from AGC, 
whether you like everything above the threshold to be flat (S4 and 40 
over S9 are the same level) or some sort of slope (2:1, 10:1 whatever) 
so stronger signals are somewhat louder.


73,

Lyle KK7P

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Re: [Elecraft] K3 AGC?

[DOUGLAS ZWIEBEL]

Wow...now were talkin!

Which causes me to have a T-shirt idea:

K3: Now THAT'S what I'm talkin about!

On 4/28/07, Lyle Johnson <[EMAIL PROTECTED]> wrote:

> I see AGC-S on the display.  I assume that there is also AGC-F and
> AGC-off, but are there any other tinkering options for the AGC?

AGC Fast and AGS Slow can be toggled by a TAP of the AGC button on the
front panel.  HOLD that button and you get AGC OFF (or ON if it was
already OFF).

In the menu, you can set the following parameters for AGC:

Attack time, Hold (Hang) time, Decay rate (in dB/sec for Fast and Slow),
Threshold, and Slope.  Slope sets the compression you get from AGC,
whether you like everything above the threshold to be flat (S4 and 40
over S9 are the same level) or some sort of slope (2:1, 10:1 whatever)
so stronger signals are somewhat louder.

73,

Lyle KK7P



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Re: [Elecraft] K3: AGC Adjustment

[Arie Kleingeld PA3A]

Ken,

SLP High number = flat output for strong and weak sigs. Just give it a try
and see for yourself.

PLS: always on, it suppresses the AGC reaction to short pulses.
Never turned it off here. A lot has been written about this subject.
See: www.sherweng.com, presentation about:  DSP Radios - Not Perfect


73
Arie PA3A

-Oorspronkelijk bericht-
Van: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] Namens Kenneth Waites
Verzonden: woensdag 9 december 2009 6:37
Aan: elecraft@mailman.qth.net
Onderwerp: [Elecraft] K3: AGC Adjustment

Question 1: AGC SLP: The manual reads wrong to me in the discussion pp 53. 
Wouldn't a slope of zero keep signals from going up in volume more so than a
slope of 10?  I think of a higher slope meaning faster audio increase as
signals get stronger.
 
Question 2:  Under what conditions do you want to change AGC PLS?
 
Ken K5WK
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Re: [Elecraft] K3: AGC Adjustment

[Don Wilhelm]

Ken,

Answer 1: The slope number refers to the AGC action, and that is the 
inverse of the audio response.   If charts are helpful to you, Jack 
Smith has measured and plotted the AGC response for the K3 - see 
http://www.cliftonlaboratories.com/elecraft_k3_agc_and_s-meter.htm#AGC_SLP_and_AGC_THR

73,
Don W3FPR

Kenneth Waites wrote:
> Question 1: AGC SLP: The manual reads wrong to me in the discussion pp 53.  
> Wouldn't a slope of zero keep signals from going up in volume more so than a 
> slope of 10?  I think of a higher slope meaning faster audio increase as 
> signals get stronger.
>   
>
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Re: [Elecraft] K3: AGC Adjustment

[drewko]

I also wondered about that. The slope of a line (the ratio of vertical
to horizontal displacement) is flatter for lower values. But in the K3
a smaller SLP value means a steeper AGC curve (the AF output changes
more for a given change in RF signal). SLP=0 really means least AGC
action, not flattest AGC, so the manual description is correct.


73,
Drew
AF2Z



On Tue, 08 Dec 2009 21:37:16 -0800 (PST), Ken K5WK wrote:

>Question 1: AGC SLP: The manual reads wrong to me in the discussion pp 53.  
>Wouldn't a slope of zero keep signals from going up in volume more so than a 
>slope of 10?  I think of a higher slope meaning faster audio increase as 
>signals get stronger.
> 
>Question 2:  Under what conditions do you want to change AGC PLS?
> 
>Ken K5WK
>__

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Re: [Elecraft] K3: AGC Adjustment

[David Ferrington, M0XDF]

That certainly helps me a lot, I have been struggling with K3 AGC  
settings and this helps a lot, I don't remember seeing this posted  
before.

So thanks to Don for posting the link and many, many thanks to Jack  
for making it clearer.
I just need to read that a few more times now.
73 de M0XDF, K3 #174
-- 
Everything secret degenerates, even the administration of justice;  
nothing
is safe that does not show how it can bear discussion and publicity.
-Lord Acton, historian (1834-1902)

On 9 Dec 2009, at 13:15, Don Wilhelm wrote:
> If charts are helpful to you, Jack
> Smith has measured and plotted the AGC response for the K3 - see
> http://www.cliftonlaboratories.com/elecraft_k3_agc_and_s-meter.htm#AGC_SLP_and_AGC_THR

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Re: [Elecraft] K3: AGC Adjustment

[Olli Tuppurainen]

I have found so many different adjustment parameters for AGC in K3 that I
would apperciate " AGC settings for dummies " type of instructions.  :)

I previously owned IC-756PRO3 which can be used as reference of well
functioning AGC among DSP radios. Very pleasant experience.

Olli
OH6CT


> -Alkuperäinen viesti-
> Lähettäjä: elecraft-boun...@mailman.qth.net 
> [mailto:elecraft-boun...@mailman.qth.net] Puolesta David 
> Ferrington, M0XDF
> Lähetetty: 9. joulukuuta 2009 17:53
> Vastaanottaja: elecraft@mailman.qth.net
> Aihe: Re: [Elecraft] K3: AGC Adjustment
> 
> That certainly helps me a lot, I have been struggling with K3 
> AGC settings and this helps a lot, I don't remember seeing 
> this posted before.
> 
> So thanks to Don for posting the link and many, many thanks 
> to Jack for making it clearer.
> I just need to read that a few more times now.
> 73 de M0XDF, K3 #174
> --
> Everything secret degenerates, even the administration of 
> justice; nothing is safe that does not show how it can bear 
> discussion and publicity.
> -Lord Acton, historian (1834-1902)
> 
> On 9 Dec 2009, at 13:15, Don Wilhelm wrote:
> > If charts are helpful to you, Jack
> > Smith has measured and plotted the AGC response for the K3 - see 
> > 
> http://www.cliftonlaboratories.com/elecraft_k3_agc_and_s-meter.htm#AGC
> > _SLP_and_AGC_THR
> 
> __
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> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> 

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Re: [Elecraft] K3: AGC Adjustment

[Don Wilhelm]

Olli,

I don't think it is so difficult that one needs "AGC for dummies".  If 
you want every signal to have about the same audio level, then set the 
slope to a higher number, but if you want to hear that a strong signal 
is louder than a weaker signal by ear (without looking at the S-meter), 
then go for a smaller numbered slope.  That is what Jack Smith's charts 
indicate - and I have set my slope to 2 since that setting is close to 
the AGC response on the K2 which I liked.

The threshold is set so the AGC will not be active on weak signals - the 
lower the number, the lower the AGC action will start - set too low, the 
AGC can become active on band noise and will de-sense the receiver even 
though there are no signals present.  How much band noise is present 
will depend on atmospheric conditions, local QRN, and your antenna.

The beauty of the K3 is that it allows you to change the AGC behavior.  
If you are not of a mind to study the effect of various setting, I 
believe you would just leave it set at the defaults until you are ready 
to investigate the possibilities and learn about them - that is what 
defaults are all about IMHO.

73,
Don W3FPR

Olli Tuppurainen wrote:
> I have found so many different adjustment parameters for AGC in K3 that I
> would apperciate " AGC settings for dummies " type of instructions.  :)
>
> I previously owned IC-756PRO3 which can be used as reference of well
> functioning AGC among DSP radios. Very pleasant experience.
>
> Olli
> OH6CT
>   
>
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Re: [Elecraft] K3: AGC Adjustment

[Doug Turnbull]

Gentlemen,
I truly love this reflector and my sincere thanks to Jack Smith of
Clifton Labs for this interesting piece.   The ultimate user manual for the
K3 might rival Webster's in its weight.

   73 Doug EI2CN

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of David Ferrington,
M0XDF
Sent: 09 December 2009 15:53
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3: AGC Adjustment

That certainly helps me a lot, I have been struggling with K3 AGC  
settings and this helps a lot, I don't remember seeing this posted  
before.

So thanks to Don for posting the link and many, many thanks to Jack  
for making it clearer.
I just need to read that a few more times now.
73 de M0XDF, K3 #174
-- 
Everything secret degenerates, even the administration of justice;  
nothing
is safe that does not show how it can bear discussion and publicity.
-Lord Acton, historian (1834-1902)

On 9 Dec 2009, at 13:15, Don Wilhelm wrote:
> If charts are helpful to you, Jack
> Smith has measured and plotted the AGC response for the K3 - see
>
http://www.cliftonlaboratories.com/elecraft_k3_agc_and_s-meter.htm#AGC_SLP_a
nd_AGC_THR

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Re: [Elecraft] K3: AGC Adjustment

[Fred Jensen]

Don Wilhelm wrote:

> I don't think it is so difficult that one needs "AGC for dummies".  If 
> you want every signal to have about the same audio level, then set the 
> slope to a higher number, but if you want to hear that a strong signal 
> is louder than a weaker signal by ear (without looking at the S-meter), 
> then go for a smaller numbered slope.  That is what Jack Smith's charts 
> indicate - and I have set my slope to 2 since that setting is close to 
> the AGC response on the K2 which I liked.
> 
> The threshold is set so the AGC will not be active on weak signals - the 
> lower the number, the lower the AGC action will start - set too low, the 
> AGC can become active on band noise and will de-sense the receiver even 
> though there are no signals present.  How much band noise is present 
> will depend on atmospheric conditions, local QRN, and your antenna.

Possibly, that WAS "K3 AGC For Dummies."  I'm gonna go look at mine, I 
was bewildered at first.  Maybe now, not so much.

73,

Fred K6DGW
Auburn CA USA
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Re: [Elecraft] K3: AGC question

[Toby Deinhardt]

> Didn't I read somewhere that in the architecture of the K3, the AGC
> only operates when necessary to prevent the DSP from being overloaded?

This refers to the hardware AGC.

In the case of the strange AGC behavior, I would think the the digital 
AGC is meant, which is "only" math in the DSP code.


vy 73 de toby
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Re: [Elecraft] K3: AGC question

[G4ILO]

John   [K7SVV] wrote:
> 
> While checking the problem that someone reported a little while ago with
> the 
> S meter being stuck when the AGC is turned off, I noticed that  I don't
> hear 
> any difference in the received signal when I turn AGC off and on.  I have 
> tried it with an S5 CW signal, an S9 SSB signal, and 40 over 9 signal on
> the 
> AM broadcast band.  I would expect each of these signals to much louder
> when 
> the AGC is switched off but I hear no change at all.  Strange, it is like 
> the AGC is not being turned off.  How about the rest of you fellows, what
> do 
> you hear?
> 
Didn't I read somewhere that in the architecture of the K3, the AGC only
operates when necessary to prevent the DSP from being overloaded? So perhaps
you are just not listening to strong enough signals for it to have an
effect.

-
Julian, G4ILO K2 s/n: 392  K3 s/n: 222
G4ILO's Shack: www.g4ilo.com
Zerobeat Ham Forums: www.zerobeat.net/smf
-- 
View this message in context: 
http://www.nabble.com/K3%3A-AGC-question-tp14959697p14961432.html
Sent from the Elecraft mailing list archive at Nabble.com.

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Re: [Elecraft] K3 AGC bad

[Brendan Minish]

On Thu, 2008-02-21 at 13:50 +, Charles Harpole wrote:
> My K3 is a super CW rig and a poor SSB rig. at least to this date
>  
> 
> 1.  AGC blasts from weak to strong sig... does not smooth out the audio enuf.

You can adjust this acg response if you want flatter ,  refer to manual
and adjust to personal taste from flat (limiting ) like to the icom 7800
to very rounded Like some k2's 
there is a lot of control over how the AGC works 

> Vy short tone sigs pierce my eardrums.
> No excuse for this problem.

What problem, explain please?   

> A fix, pse???

have you tried calibrating the PLL? 


> 2. Tighter than 2.20 and the SSB audio really degrades.
> This is either a great filter system or my earlier rigs'
> (Mk 5 etc.) nice 1.8 INRAD filters were not that sharp.
> Below 2.00 on ssb and the voices lose too much of 
> their intelligibility, sad to say, because I need
> 1.8, or so, to kill the guy 2 kc above.

 select lo-hi cut and adjust, it's fine, I regularly use 1.8 or less on
SSB here 

>  
> 3.  Many ssb sigs sound harsh and too sharp even
> at 2.8, especially when 5 or more are calling at
> the same time.  Adding bass with the cut knob helps some.
> Using Heil ProSet Plus.

use high and low cut on the filters, perhaps Taylor the RX EQ to suit
your ears. 
>  
> 4.  NR at any setting degrades weaker ssb sigs beyond
> usefulness.  Why is this?

noise noise reduction, in DSP can not, (no mater what code is used)
deliver the impossible and render readable an SSB sig that is brueid in
the noise. the K3 noise reduction is the best I have heard on any radio
to date but I still prefer it off most of the time and let the brain do
it   
 
> 
> And, the temporary info that appears BRIEFLY in the
> vfo B window is too brief for me.
> A fix, pse

NO Fix please! the delay is right for me ! 


I came to the K3 from the Icom 7800, the 7800 is for sale I know which
one I prefer to listen to.
 

73
Brendan EI6IZ 


-- 
Don‘t complain. Nobody will understand. Or care. And certainly don‘t try
to fix the situation yourself. It‘s dangerous. Leave it to a highly
untrained, unqualified, expendable professional.

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RE: [Elecraft] K3 AGC reply

[Charles Harpole]

Brendan gave me great advice which I will pursue.  Big thanks, 73Charles [EMAIL 
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RE: [Elecraft] K3 AGC bad

[N1IX]

Thank goodness I don't own a microphone.



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brendan Minish
Sent: Thursday, February 21, 2008 9:13 AM
To: Charles Harpole
Cc: Elecraft
Subject: Re: [Elecraft] K3 AGC bad


On Thu, 2008-02-21 at 13:50 +, Charles Harpole wrote:
> My K3 is a super CW rig and a poor SSB rig. at least to this date
>  
> 
> 1.  AGC blasts from weak to strong sig... does not smooth out the audio enuf.

You can adjust this acg response if you want flatter ,  refer to manual
and adjust to personal taste from flat (limiting ) like to the icom 7800
to very rounded Like some k2's 
there is a lot of control over how the AGC works 

> Vy short tone sigs pierce my eardrums.
> No excuse for this problem.

What problem, explain please?   

> A fix, pse???

have you tried calibrating the PLL? 


> 2. Tighter than 2.20 and the SSB audio really degrades.
> This is either a great filter system or my earlier rigs'
> (Mk 5 etc.) nice 1.8 INRAD filters were not that sharp.
> Below 2.00 on ssb and the voices lose too much of 
> their intelligibility, sad to say, because I need
> 1.8, or so, to kill the guy 2 kc above.

 select lo-hi cut and adjust, it's fine, I regularly use 1.8 or less on
SSB here 

>  
> 3.  Many ssb sigs sound harsh and too sharp even
> at 2.8, especially when 5 or more are calling at
> the same time.  Adding bass with the cut knob helps some.
> Using Heil ProSet Plus.

use high and low cut on the filters, perhaps Taylor the RX EQ to suit
your ears. 
>  
> 4.  NR at any setting degrades weaker ssb sigs beyond
> usefulness.  Why is this?

noise noise reduction, in DSP can not, (no mater what code is used)
deliver the impossible and render readable an SSB sig that is brueid in
the noise. the K3 noise reduction is the best I have heard on any radio
to date but I still prefer it off most of the time and let the brain do
it   
 
> 
> And, the temporary info that appears BRIEFLY in the
> vfo B window is too brief for me.
> A fix, pse

NO Fix please! the delay is right for me ! 


I came to the K3 from the Icom 7800, the 7800 is for sale I know which
one I prefer to listen to.
 

73
Brendan EI6IZ 


-- 
Don‘t complain. Nobody will understand. Or care. And certainly don‘t try
to fix the situation yourself. It‘s dangerous. Leave it to a highly
untrained, unqualified, expendable professional.

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Re: [Elecraft] K3 AGC bad

[Dave Larson]

When using the 1.8 kc filter on SSB, turn the shift knob counter clockwise 
and you will find very good intelligibility.


Dave, K8AA
K3 #271

- Original Message - 
From: "Charles Harpole" <[EMAIL PROTECTED]>
To: "Jim Cox" <[EMAIL PROTECTED]>; "N1IX" <[EMAIL PROTECTED]>; "Elecraft" 
; <[EMAIL PROTECTED]>

Sent: Thursday, February 21, 2008 8:50 AM
Subject: [Elecraft] K3 AGC bad



My K3 is a super CW rig and a poor SSB rig. at least to this date


1.  AGC blasts from weak to strong sig... does not smooth out the audio 
enuf.

Vy short tone sigs pierce my eardrums.
No excuse for this problem.
A fix, pse???

2. Tighter than 2.20 and the SSB audio really degrades.
This is either a great filter system or my earlier rigs'
(Mk 5 etc.) nice 1.8 INRAD filters were not that sharp.
Below 2.00 on ssb and the voices lose too much of
their intelligibility, sad to say, because I need
1.8, or so, to kill the guy 2 kc above.

3.  Many ssb sigs sound harsh and too sharp even
at 2.8, especially when 5 or more are calling at
the same time.  Adding bass with the cut knob helps some.
Using Heil ProSet Plus.

4.  NR at any setting degrades weaker ssb sigs beyond
usefulness.  Why is this?



And, the temporary info that appears BRIEFLY in the
vfo B window is too brief for me.
A fix, pse

I gotta get my shack computer on line agn to get updates.  In my
appliance op uses to date, K3 is not sliced bread on ssb.

73Charles Harpole  [EMAIL PROTECTED] 
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Re: [Elecraft] K3: AGC mod

[a.yoshida]

Don

Thanks for your comment.
Although AGC OFF is a way to avoid annoying action my EAR does not prefer  
sudden

loud audio.  I will enjoy "unsoldering SMD parts" ,  Hi

Thanks


On Mon, 31 Mar 2008 01:17:16 +0900, Don Rasmussen <[EMAIL PROTECTED]> wrote:


Aki - I have noticed that the HAGC mod makes the AGC
THR seem to have more range and effect at the higher
values. I also now use my AGC in the OFF position for
CW, I enjoy the most energy in the audio and less of a
smoothing effect.

However for SSB and AM I require more of a smoothing
effect as if AGC THR is even lower than the lowest
available setup parameter, which I will be looking for
in the next firmware update.

This is all very low priority for me however because
the K3 is already better than anything I have ever
tried before. ;-)


[Elecraft] K3: AGC mod
a.yoshida ayoshida at my.email.ne.jp
Sun Mar 30 07:59:38 EST 2008

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Hello

I am one of happy K3 users. S/N 00060

I found annoying AGC action when operating CW with
2.8KHz filter
even if I configure AGC THR in config menu to highest
value.

Can we expect more improvement with AGC mod ?

I have already ordered CW rise time mod kit and AGC
mod kit though.





--
73 de aki, ja1nlx
http://www.asahi-net.or.jp/~yy7a-ysd/
http://ja1nlx.blog109.fc2.com/
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Re: [Elecraft] K3: AGC misbehaving

[Barry Simpson]

Hi Ralph and Elecrafters

I believe I am experiencing the same issue as you as regards slow AGC. What
happens with a strong CW station is that the s meter peaks then falls away
rapidly for the first few characters before settling down. Is this what you
are experiencing Ralph ?

Barry Simpson  VK2BJ  K3 1397


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Re: [Elecraft] K3: AGC misbehaving

[John A. McCabe]

You may want to try setting AGC PLS=OFF. I notice the same thing when 
this setting is on. With this setting on, It appears to me that the AGC 
pulse rejection will cause the AGC to react too quickly on some CW 
elements .

73,

John, KD8K


Ralph Parker wrote:
> While listening casually to the NA contest today, I noticed that the AGC
> was behaving thusly:
>
> In CW mode, the ACG is set to 'SLOW' (I prefer it that way). Firmware 2.72.
> When receiving a relatively strong signal, the AGC seemed to be in 'FAST'
> mode for the first 1-2 seconds, then in 'SLOW' mode for the rest of the
> transmission. This would repeat for every received transmission.
> I was not transmitting at any time.
> Am I overlooking an AGC CONFIG setting?
>
> VE7XF
>
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Re: [Elecraft] K3 AGC Mush

[David Gilbert]

This has been a very real problem for serious contesters and is the 
number one dissatisfaction I have with the K3 ... and with Elecraft.

Multiple low level CW signals within a narrow passband simply turn to 
mush and are very difficult to distinguish.  I use the bare minimum AGC 
settings in an attempt to cope since turning AGC completely off during a 
contest can be painful to both the ears and the K3 itself (as those who 
have had to replace their audio ICs can attest) but that often does not 
adequately deal with the problem.  I have had little doubt that the 
culprit is some kind of low end nonlinearity and it is nice to know that 
your measurements tend to confirm that, but what I simply don't 
understand is why we have heard so little from Elecraft on this topic.  
On just about every other issue (even mind-blowingly trivial ones) 
Elecraft has responded quickly and effectively with both an explanation 
and a solution, but on this very important one we have heard virtually 
nothing and there seems to be no viable solution on the horizon.  I 
don't know if Elecraft doesn't believe the problem actually exists 
(possible, since I don't think any of the principle players consider 
themselves contesters first and foremost) or if they don't believe it is 
important or if they simply don't have a solution.  The silence has been 
deafening, though.

I personally know at least two top-tier contesters that are seriously 
considering replacing their K3s with a different rig because of this 
single issue, and I personally know two others who did not buy a K3 
because of it.  If I knew then what I know now I would not have bought 
my K3 either.  I spent a lot of money (tower, antennas, amplifiier) to 
be able to put a strong signal into various DX locations, and it is 
simply embarrassing to be working a pileup with a half dozen weak 
callers that obviously can hear me fine and not be able to pick their 
callsigns out of the mush.

No, it is not my ears and no, it is not my ability to copy CW.

Sorry for the rant, but I'm really really really tired of this 
fundamental problem being ignored.  We at least deserve some sort of 
explanation.

Dave   AB7E



On 12/4/2011 7:11 AM, Cady, Fred wrote:
> Neat site but unfortunately none of the audio clips demonstrate the
> pileups heard at dx locations like C6AAW. Once again this year the K3s
> AGC failed to perform adequately for us. I found many times I just had
> to turn AGC off. Signals were much cleaner and more distinguishable.
> I think there are two things going on. First, I think the threshold
> cannot be set high enough. The maximum is around S3 according to my
> measurements. Thus, when you have a pileup of signals all in the S3, S4,
> S5 region, which is common, AGC is compressing them together. When AGC
> is off, these signals are now in a linear region of the transfer curve
> and can be distinguished more easily. Second, and this is hard for me to
> judge since it has been a while since I've used an analog audio
> processing radio like the TS850, the audio doesn't sound "good". I
> dunno. I think there is an inherent harshness(?) to digitally produced
> audio as compared to analog audio. I'm not an audio guy, for sure.
>
> Sadly, I suspect top contesters are beginning to look for another radio
> to replace the K3 :-(
>
> 73,
> Fred
> KE7X/C6AKX/C6AAW
>
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Re: [Elecraft] K3 AGC Mush

[Eric Swartz WA6HHQ - Elecraft]

Hi David,

We're keenly aware of this and have been trying to reproduce this here 
in the lab for a long time without success.

This is an issue that has been reported for years on a wide range of 
radios from all of the manufacturers, with conflicting reports pro/con 
on each radio.  Each person reporting mush on RX has a different idea of 
what they are hearing too. We have received anecdotal reports of RX mush 
on huge pile-ups from some  stations, and reports of absolutely no mush 
from others who are operating in the same situations at the receiving 
end of the pile-ups. (including from the recent CQWW contest.)

We are working directly with a number of contesters and DXers to see 
what can be done to parametrize what is actually happening and to make 
this easier to reproduce in a testable situation. We've tested versus 
other radios here and have worked with a number of those who have 
reported this issue. Its frustrating as we are unable to create a 
repeatable stimulus situation where we can test and evaluate different 
approaches to AGC and other areas that might impact 'mush'.

Also of interest is the rise of reverse spotting networks and the 
resulting high number of stations calling DX on -exactly- the same 
frequency, which is a huge problem for any radio. This may be increasing 
the reports of RX pile-up mush as large numbers of callers follow the 
packet and reverse spotting network reports.

Also, in the heat of the contest or DX pile up most reporters do not 
recall how they had their AGC parameters set (threshold, slope, AGC 
decay soft/hard, fast or slow, and fast/slow settings etc. If you can 
let us know your complete set up for AGC parameters, if you are using 
headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what 
different settings you tried etc., that will be extremely helpful.

One note - If signals are below S9+20 and turning AGC off does not help, 
its probably not a DSP AGC or H/W AGC issue.

Also, make sure to use the AGC Limiter menu setting to hard limit audio 
levels if you use AGC OFF.

We're in the process of trying a number of items and here will post here 
as soon as we have something definitive. Please feel free to email us 
directly with anything you think might help us get a handle on this.

73, Eric
www.elecraft.com


_..._


On 12/4/2011 9:55 AM, David Gilbert wrote:
> This has been a very real problem for serious contesters and is the
> number one dissatisfaction I have with the K3 ... and with Elecraft.
>
> Multiple low level CW signals within a narrow passband simply turn to
> mush and are very difficult to distinguish.  I use the bare minimum AGC
> settings in an attempt to cope since turning AGC completely off during a
> contest can be painful to both the ears and the K3 itself (as those who
> have had to replace their audio ICs can attest) but that often does not
> adequately deal with the problem.
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Re: [Elecraft] K3 AGC Mush

[Merv Schweigert]

> Also, in the heat of the contest or DX pile up most reporters do not
> recall how they had their AGC parameters set (threshold, slope, AGC
> decay soft/hard, fast or slow, and fast/slow settings etc. If you can
> let us know your complete set up for AGC parameters, if you are using
> headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
> different settings you tried etc., that will be extremely helpful.
>
AGC DCY  =  NOR
AGG HLD  =  20
AGC PLS  =  NOR
AGC SLP  = 000
AGC THR =  008
AGC F  = 200
AGC S = 020

Headphones and speaker, no difference
signals S3-S4 range
CW
all bandwidths,  use mostly 400hz and narrower.
Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
ALL settings of SLP and THR
Turning off the AGC  improves the "mush".
Loud signals are no problem at all,  the K3 handles loud signals better than
any radio..  its when multiple signals of about S-4 are on this occurs,  
more
than two or three, a pile up of same strength signals.
I can understand it may difficult to reproduce unless you have a way to 
have
10 signals of the same strength, close to the same freq, and keying,  just a
carrier will not reproduce the effect,  has to be keyed signals you are 
trying
to copy.  They turn into a single level buzz of sorts.

One note - If signals are below S9+20 and turning AGC off does not help,
> its probably not a DSP AGC or H/W AGC issue.
>
> Also, make sure to use the AGC Limiter menu setting to hard limit audio
> levels if you use AGC OFF.
>
Never use NR or NB  and have the AGC limiter set for no AGC times.

In my rough gestimation it seems that signals in the S3-S4 range need to 
not trigger
the AGC as they do,  if one could set the THR to higher level? perhaps 
it would stop the
problem.
Is it possible to increase the range of SLP and THR to move the point 
where S-3 or S-4
signals trigger the AGC?
Thanks much Eric.73 Merv K9FD/KH6
>

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Re: [Elecraft] K3 AGC Mush

[Jan Erik Holm]

This is exactly what I have noticed too. Not even 10 signals
are needed either.
/SM2EKM
---
On 2011-12-04 20:53, Merv Schweigert wrote:
>
>> Also, in the heat of the contest or DX pile up most reporters do not
>> recall how they had their AGC parameters set (threshold, slope, AGC
>> decay soft/hard, fast or slow, and fast/slow settings etc. If you can
>> let us know your complete set up for AGC parameters, if you are using
>> headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
>> different settings you tried etc., that will be extremely helpful.
>>
> AGC DCY  =  NOR
> AGG HLD  =  20
> AGC PLS  =  NOR
> AGC SLP  = 000
> AGC THR =  008
> AGC F  = 200
> AGC S = 020
>
> Headphones and speaker, no difference
> signals S3-S4 range
> CW
> all bandwidths,  use mostly 400hz and narrower.
> Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
> ALL settings of SLP and THR
> Turning off the AGC  improves the "mush".
> Loud signals are no problem at all,  the K3 handles loud signals better than
> any radio..  its when multiple signals of about S-4 are on this occurs,
> more
> than two or three, a pile up of same strength signals.
> I can understand it may difficult to reproduce unless you have a way to
> have
> 10 signals of the same strength, close to the same freq, and keying,  just a
> carrier will not reproduce the effect,  has to be keyed signals you are
> trying
> to copy.  They turn into a single level buzz of sorts.
>
> One note - If signals are below S9+20 and turning AGC off does not help,
>> its probably not a DSP AGC or H/W AGC issue.
>>
>> Also, make sure to use the AGC Limiter menu setting to hard limit audio
>> levels if you use AGC OFF.
>>
> Never use NR or NB  and have the AGC limiter set for no AGC times.
>
> In my rough gestimation it seems that signals in the S3-S4 range need to
> not trigger
> the AGC as they do,  if one could set the THR to higher level? perhaps
> it would stop the
> problem.
> Is it possible to increase the range of SLP and THR to move the point
> where S-3 or S-4
> signals trigger the AGC?
> Thanks much Eric.73 Merv K9FD/KH6
>>
>
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Re: [Elecraft] K3 AGC Mush

[Jan Erik Holm]

Could be interesting if you could name at least a few
of these radios?
/SM2EKM
---
On 2011-12-04 20:14, Eric Swartz WA6HHQ - Elecraft wrote:
>
> This is an issue that has been reported for years on a wide range of
> radios from all of the manufacturers, with conflicting reports pro/con
> on each radio.
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Re: [Elecraft] K3 AGC Mush

[Guy Olinger K2AV]

How about ALL of them.  It's not really solved transparent to operator
smarts on ANYBODY'S RX.73, Guy.

On Sun, Dec 4, 2011 at 3:22 PM, Jan Erik Holm  wrote:
> Could be interesting if you could name at least a few
> of these radios?
> /SM2EKM
> ---
> On 2011-12-04 20:14, Eric Swartz WA6HHQ - Elecraft wrote:
>>
>> This is an issue that has been reported for years on a wide range of
>> radios from all of the manufacturers, with conflicting reports pro/con
>> on each radio.
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Re: [Elecraft] K3 AGC Mush

[Eric Swartz WA6HHQ - Elecraft]

We actually have a 'pile-up' generator we designed that sends multiple 
cw signals. So far it has not reproduced the issue here.

What is the signal spacing you are hearing this with? All -exactly- on 
the same freq? Or spread out?

73, Eric

_..._


On 12/4/2011 12:20 PM, Jan Erik Holm wrote:
> This is exactly what I have noticed too. Not even 10 signals
> are needed either.
> /SM2EKM
> ---
> On 2011-12-04 20:53, Merv Schweigert wrote:
>>> Also, in the heat of the contest or DX pile up most reporters do not
>>> recall how they had their AGC parameters set (threshold, slope, AGC
>>> decay soft/hard, fast or slow, and fast/slow settings etc. If you can
>>> let us know your complete set up for AGC parameters, if you are using
>>> headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
>>> different settings you tried etc., that will be extremely helpful.
>>>
>> AGC DCY  =  NOR
>> AGG HLD  =  20
>> AGC PLS  =  NOR
>> AGC SLP  = 000
>> AGC THR =  008
>> AGC F  = 200
>> AGC S = 020
>>
>> Headphones and speaker, no difference
>> signals S3-S4 range
>> CW
>> all bandwidths,  use mostly 400hz and narrower.
>> Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
>> ALL settings of SLP and THR
>> Turning off the AGC  improves the "mush".
>> Loud signals are no problem at all,  the K3 handles loud signals better than
>> any radio..  its when multiple signals of about S-4 are on this occurs,
>> more
>> than two or three, a pile up of same strength signals.
>> I can understand it may difficult to reproduce unless you have a way to
>> have
>> 10 signals of the same strength, close to the same freq, and keying,  just a
>> carrier will not reproduce the effect,  has to be keyed signals you are
>> trying
>> to copy.  They turn into a single level buzz of sorts.
>>
>> One note - If signals are below S9+20 and turning AGC off does not help,
>>> its probably not a DSP AGC or H/W AGC issue.
>>>
>>> Also, make sure to use the AGC Limiter menu setting to hard limit audio
>>> levels if you use AGC OFF.
>>>
>> Never use NR or NB  and have the AGC limiter set for no AGC times.
>>
>> In my rough gestimation it seems that signals in the S3-S4 range need to
>> not trigger
>> the AGC as they do,  if one could set the THR to higher level? perhaps
>> it would stop the
>> problem.
>> Is it possible to increase the range of SLP and THR to move the point
>> where S-3 or S-4
>> signals trigger the AGC?
>> Thanks much Eric.73 Merv K9FD/KH6
>>
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Re: [Elecraft] K3 AGC Mush

[Brian Alsop]

Interesting.

Just a thought:
To rule out or identify hardware problems, I wonder if someone with 
"mush" problem would be willing to loan Elecraft the offending rig?

I wonder just how "exactly" on frequency guys calling from spots really 
are?  Spots are quantized in 0.1 KHz steps.  Many radios are off by 100 
Hz.  So it is easy to imagine the responders calling within a 150-200Hz 
window.  That's still a mess.

73 de Brian/K3KO


On 12/4/2011 20:22, Jan Erik Holm wrote:
> Could be interesting if you could name at least a few
> of these radios?
> /SM2EKM
> ---
> On 2011-12-04 20:14, Eric Swartz WA6HHQ - Elecraft wrote:
>>
>> This is an issue that has been reported for years on a wide range of
>> radios from all of the manufacturers, with conflicting reports pro/con
>> on each radio.
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>
> -
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1411 / Virus Database: 2102/4056 - Release Date: 12/04/11
>
>



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Re: [Elecraft] K3 AGC Mush

[Jan Erik Holm]

It is not "on the same" frequency problem, however signals
are quite close together but it´s difficult to say exactly
how close.
The thing is that the "signal package" has to be weak enough,
lets say in the S4-S6 region, if you make the same signal
package stronger the problem will go away.
I would say you need at least 3 signals or maybe 4 to 5 to
get the problem.
I do understand that it would be very difficult to reproduce,
after all the noise floor might even be a key factor, at least
I do think so.
Well at least it´s nice to know that Elecraft is working on it.

Oh by the way, I just computerized all my paper logs and do find
QSO´s with WA6HHQ back in 1973 1976 and 1998, jeez 1973 a long
time ago.

73 Jim SM2EKM

On 2011-12-04 21:31, Eric Swartz WA6HHQ - Elecraft wrote:
> We actually have a 'pile-up' generator we designed that sends multiple
> cw signals. So far it has not reproduced the issue here.
>
> What is the signal spacing you are hearing this with? All -exactly- on
> the same freq? Or spread out?
>
> 73, Eric
>
> _..._
>
>
> On 12/4/2011 12:20 PM, Jan Erik Holm wrote:
>> This is exactly what I have noticed too. Not even 10 signals
>> are needed either.
>> /SM2EKM
>> ---
>> On 2011-12-04 20:53, Merv Schweigert wrote:
 Also, in the heat of the contest or DX pile up most reporters do not
 recall how they had their AGC parameters set (threshold, slope, AGC
 decay soft/hard, fast or slow, and fast/slow settings etc. If you can
 let us know your complete set up for AGC parameters, if you are using
 headphones or speakers, the signal strengths, CW or SSB, RX b/w, what
 different settings you tried etc., that will be extremely helpful.

>>> AGC DCY = NOR
>>> AGG HLD = 20
>>> AGC PLS = NOR
>>> AGC SLP = 000
>>> AGC THR = 008
>>> AGC F = 200
>>> AGC S = 020
>>>
>>> Headphones and speaker, no difference
>>> signals S3-S4 range
>>> CW
>>> all bandwidths, use mostly 400hz and narrower.
>>> Tried AGC DCY = SOFT (have PF1 programmed to switch that in and out
>>> fast)
>>> ALL settings of SLP and THR
>>> Turning off the AGC improves the "mush".
>>> Loud signals are no problem at all, the K3 handles loud signals
>>> better than
>>> any radio.. its when multiple signals of about S-4 are on this occurs,
>>> more
>>> than two or three, a pile up of same strength signals.
>>> I can understand it may difficult to reproduce unless you have a way to
>>> have
>>> 10 signals of the same strength, close to the same freq, and keying,
>>> just a
>>> carrier will not reproduce the effect, has to be keyed signals you are
>>> trying
>>> to copy. They turn into a single level buzz of sorts.
>>>
>>> One note - If signals are below S9+20 and turning AGC off does not help,
 its probably not a DSP AGC or H/W AGC issue.

 Also, make sure to use the AGC Limiter menu setting to hard limit audio
 levels if you use AGC OFF.

>>> Never use NR or NB and have the AGC limiter set for no AGC times.
>>>
>>> In my rough gestimation it seems that signals in the S3-S4 range need to
>>> not trigger
>>> the AGC as they do, if one could set the THR to higher level? perhaps
>>> it would stop the
>>> problem.
>>> Is it possible to increase the range of SLP and THR to move the point
>>> where S-3 or S-4
>>> signals trigger the AGC?
>>> Thanks much Eric. 73 Merv K9FD/KH6
>>>
>

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Re: [Elecraft] K3 AGC Mush

[Merv Schweigert]

I start noticing it with more than 4 or so stations calling and with all
within the passband of the filter in use,  so if I have the 400HZ filter
in and DSP set for 400 the callers can be up to almost 400hz apart,
I have heard it with the 1.0 filter as well.
At first I thought it may have been due to a strong signal just outside
the filter,  but I have checked many times and there is nothing there,
no strong signals within several KHZ even.  So it appears to be
generated from the signals inside the filter width.
If this is isolated to my radio and or a couple others, thats super, I
will sell this puppy and order a new one.

As far as other radios doing the same thing,  I sold my Ten Tec and do
not remember it doing this,  I still have my FT-1000D with modified agc
and it does not do it,  it has  filters down to  125HZ
and does not do it at any bandwidth setting,  but it does not hold a
candle to the K3s strong signal handling or filtering, so it sits here idle
for the most part,  used for second radio operations, since the addition
of APF.
73 Merv K9FD/KH6

> We actually have a 'pile-up' generator we designed that sends multiple
> cw signals. So far it has not reproduced the issue here.
>
> What is the signal spacing you are hearing this with? All -exactly- on
> the same freq? Or spread out?
>
> 73, Eric
>
> _..._
>
>
> On 12/4/2011 12:20 PM, Jan Erik Holm wrote:
>
>> This is exactly what I have noticed too. Not even 10 signals
>> are needed either.
>> /SM2EKM
>> ---
>> On 2011-12-04 20:53, Merv Schweigert wrote:
>>  
 Also, in the heat of the contest or DX pile up most reporters do not
 recall how they had their AGC parameters set (threshold, slope, AGC
 decay soft/hard, fast or slow, and fast/slow settings etc. If you can
 let us know your complete set up for AGC parameters, if you are using
 headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
 different settings you tried etc., that will be extremely helpful.

  
>>> AGC DCY  =  NOR
>>> AGG HLD  =  20
>>> AGC PLS  =  NOR
>>> AGC SLP  = 000
>>> AGC THR =  008
>>> AGC F  = 200
>>> AGC S = 020
>>>
>>> Headphones and speaker, no difference
>>> signals S3-S4 range
>>> CW
>>> all bandwidths,  use mostly 400hz and narrower.
>>> Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
>>> ALL settings of SLP and THR
>>> Turning off the AGC  improves the "mush".
>>> Loud signals are no problem at all,  the K3 handles loud signals better than
>>> any radio..  its when multiple signals of about S-4 are on this occurs,
>>> more
>>> than two or three, a pile up of same strength signals.
>>> I can understand it may difficult to reproduce unless you have a way to
>>> have
>>> 10 signals of the same strength, close to the same freq, and keying,  just a
>>> carrier will not reproduce the effect,  has to be keyed signals you are
>>> trying
>>> to copy.  They turn into a single level buzz of sorts.
>>>
>>> One note - If signals are below S9+20 and turning AGC off does not help,
>>>
 its probably not a DSP AGC or H/W AGC issue.

 Also, make sure to use the AGC Limiter menu setting to hard limit audio
 levels if you use AGC OFF.

  
>>> Never use NR or NB  and have the AGC limiter set for no AGC times.
>>>
>>> In my rough gestimation it seems that signals in the S3-S4 range need to
>>> not trigger
>>> the AGC as they do,  if one could set the THR to higher level? perhaps
>>> it would stop the
>>> problem.
>>> Is it possible to increase the range of SLP and THR to move the point
>>> where S-3 or S-4
>>> signals trigger the AGC?
>>> Thanks much Eric.73 Merv K9FD/KH6
>>>
>>>
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Re: [Elecraft] K3 AGC Mush

[Merv Schweigert]

Eric,  thinking on this a little more, when you are testing there with 
the pile
up generator do you have real antenna noise also on the radio?
I just checked on 20 meters for example and my noise is flickering S-3
almost the same level as the signals would be in the pile up when this
problem occurs.   So signals are close to the noise level or just above.
Perhaps testing with a noise generator set to S3 and the pile up generator
set for signals of S3 to S4 it may show up?
Merv K9FD/KH6
> We actually have a 'pile-up' generator we designed that sends multiple
> cw signals. So far it has not reproduced the issue here.
>
> What is the signal spacing you are hearing this with? All -exactly- on
> the same freq? Or spread out?
>
> 73, Eric
>
> _..._
>
>
> On 12/4/2011 12:20 PM, Jan Erik Holm wrote:
>
>> This is exactly what I have noticed too. Not even 10 signals
>> are needed either.
>> /SM2EKM
>> ---
>> On 2011-12-04 20:53, Merv Schweigert wrote:
>>  
 Also, in the heat of the contest or DX pile up most reporters do not
 recall how they had their AGC parameters set (threshold, slope, AGC
 decay soft/hard, fast or slow, and fast/slow settings etc. If you can
 let us know your complete set up for AGC parameters, if you are using
 headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
 different settings you tried etc., that will be extremely helpful.

  
>>> AGC DCY  =  NOR
>>> AGG HLD  =  20
>>> AGC PLS  =  NOR
>>> AGC SLP  = 000
>>> AGC THR =  008
>>> AGC F  = 200
>>> AGC S = 020
>>>
>>> Headphones and speaker, no difference
>>> signals S3-S4 range
>>> CW
>>> all bandwidths,  use mostly 400hz and narrower.
>>> Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
>>> ALL settings of SLP and THR
>>> Turning off the AGC  improves the "mush".
>>> Loud signals are no problem at all,  the K3 handles loud signals better than
>>> any radio..  its when multiple signals of about S-4 are on this occurs,
>>> more
>>> than two or three, a pile up of same strength signals.
>>> I can understand it may difficult to reproduce unless you have a way to
>>> have
>>> 10 signals of the same strength, close to the same freq, and keying,  just a
>>> carrier will not reproduce the effect,  has to be keyed signals you are
>>> trying
>>> to copy.  They turn into a single level buzz of sorts.
>>>
>>> One note - If signals are below S9+20 and turning AGC off does not help,
>>>
 its probably not a DSP AGC or H/W AGC issue.

 Also, make sure to use the AGC Limiter menu setting to hard limit audio
 levels if you use AGC OFF.

  
>>> Never use NR or NB  and have the AGC limiter set for no AGC times.
>>>
>>> In my rough gestimation it seems that signals in the S3-S4 range need to
>>> not trigger
>>> the AGC as they do,  if one could set the THR to higher level? perhaps
>>> it would stop the
>>> problem.
>>> Is it possible to increase the range of SLP and THR to move the point
>>> where S-3 or S-4
>>> signals trigger the AGC?
>>> Thanks much Eric.73 Merv K9FD/KH6
>>>
>>>
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Re: [Elecraft] K3 AGC Mush

[Geoffrey Mackenzie-Kennedy]

Merv,

Does the mush "disappear" or noticeably decrease if you switch to a much 
wider bandwidth roofer (1800 Hz or more), while keeping the DSP's bandwidth 
set at 400 Hz or less?

73,

Geoff
LX2AO   (aka GM4ESD)


Merv Schweigert wrote on 04/12/2011 at 23:51 +0100:

>I start noticing it with more than 4 or so stations calling and with all
> within the passband of the filter in use,  so if I have the 400HZ filter
> in and DSP set for 400 the callers can be up to almost 400hz apart,
> I have heard it with the 1.0 filter as well.

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Re: [Elecraft] K3 AGC Mush

[Dale Boresz]

For me, the RF gain setting has a dramatic effect on the character of 
received signals. I rarely set it higher than about the two o'clock 
position.

Any idea of the RF gain setting while experiencing this 'mush'?

73, Dale
WA8SRA

On 12/4/2011 3:20 PM, Jan Erik Holm wrote:
> This is exactly what I have noticed too. Not even 10 signals
> are needed either.
> /SM2EKM
> ---
> On 2011-12-04 20:53, Merv Schweigert wrote:
>>> Also, in the heat of the contest or DX pile up most reporters do not
>>> recall how they had their AGC parameters set (threshold, slope, AGC
>>> decay soft/hard, fast or slow, and fast/slow settings etc. If you can
>>> let us know your complete set up for AGC parameters, if you are using
>>> headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
>>> different settings you tried etc., that will be extremely helpful.
>>>
>> AGC DCY  =  NOR
>> AGG HLD  =  20
>> AGC PLS  =  NOR
>> AGC SLP  = 000
>> AGC THR =  008
>> AGC F  = 200
>> AGC S = 020
>>
>> Headphones and speaker, no difference
>> signals S3-S4 range
>> CW
>> all bandwidths,  use mostly 400hz and narrower.
>> Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
>> ALL settings of SLP and THR
>> Turning off the AGC  improves the "mush".
>> Loud signals are no problem at all,  the K3 handles loud signals better than
>> any radio..  its when multiple signals of about S-4 are on this occurs,
>> more
>> than two or three, a pile up of same strength signals.
>> I can understand it may difficult to reproduce unless you have a way to
>> have
>> 10 signals of the same strength, close to the same freq, and keying,  just a
>> carrier will not reproduce the effect,  has to be keyed signals you are
>> trying
>> to copy.  They turn into a single level buzz of sorts.
>>
>> One note - If signals are below S9+20 and turning AGC off does not help,
>>> its probably not a DSP AGC or H/W AGC issue.
>>>
>>> Also, make sure to use the AGC Limiter menu setting to hard limit audio
>>> levels if you use AGC OFF.
>>>
>> Never use NR or NB  and have the AGC limiter set for no AGC times.
>>
>> In my rough gestimation it seems that signals in the S3-S4 range need to
>> not trigger
>> the AGC as they do,  if one could set the THR to higher level? perhaps
>> it would stop the
>> problem.
>> Is it possible to increase the range of SLP and THR to move the point
>> where S-3 or S-4
>> signals trigger the AGC?
>> Thanks much Eric.73 Merv K9FD/KH6
>> __
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Re: [Elecraft] K3 AGC Mush

[Merv Schweigert]

Yep my RF gain for the high bands is usually about 1 to 2 o'clock at most,
low bands with more static its much lower of course in the 10 to 11 most
times.
My noise level on high bands is S1 to flickering S2,  20 meters on good 
opening
is S3..   I have an idea many will never hear the problem due to their 
noise level
being higher than the signals being copied here at least..
Merv K9FD/KH6
> For me, the RF gain setting has a dramatic effect on the character of
> received signals. I rarely set it higher than about the two o'clock
> position.
>
> Any idea of the RF gain setting while experiencing this 'mush'?
>
> 73, Dale
> WA8SRA
>
> On 12/4/2011 3:20 PM, Jan Erik Holm wrote:
>
>> This is exactly what I have noticed too. Not even 10 signals
>> are needed either.
>> /SM2EKM
>> ---
>> On 2011-12-04 20:53, Merv Schweigert wrote:
>>  
 Also, in the heat of the contest or DX pile up most reporters do not
 recall how they had their AGC parameters set (threshold, slope, AGC
 decay soft/hard, fast or slow, and fast/slow settings etc. If you can
 let us know your complete set up for AGC parameters, if you are using
 headphones or speakers,  the signal strengths, CW or SSB, RX b/w, what
 different settings you tried etc., that will be extremely helpful.

  
>>> AGC DCY  =  NOR
>>> AGG HLD  =  20
>>> AGC PLS  =  NOR
>>> AGC SLP  = 000
>>> AGC THR =  008
>>> AGC F  = 200
>>> AGC S = 020
>>>
>>> Headphones and speaker, no difference
>>> signals S3-S4 range
>>> CW
>>> all bandwidths,  use mostly 400hz and narrower.
>>> Tried AGC DCY = SOFT  (have PF1 programmed to switch that in and out fast)
>>> ALL settings of SLP and THR
>>> Turning off the AGC  improves the "mush".
>>> Loud signals are no problem at all,  the K3 handles loud signals better than
>>> any radio..  its when multiple signals of about S-4 are on this occurs,
>>> more
>>> than two or three, a pile up of same strength signals.
>>> I can understand it may difficult to reproduce unless you have a way to
>>> have
>>> 10 signals of the same strength, close to the same freq, and keying,  just a
>>> carrier will not reproduce the effect,  has to be keyed signals you are
>>> trying
>>> to copy.  They turn into a single level buzz of sorts.
>>>
>>> One note - If signals are below S9+20 and turning AGC off does not help,
>>>
 its probably not a DSP AGC or H/W AGC issue.

 Also, make sure to use the AGC Limiter menu setting to hard limit audio
 levels if you use AGC OFF.

  
>>> Never use NR or NB  and have the AGC limiter set for no AGC times.
>>>
>>> In my rough gestimation it seems that signals in the S3-S4 range need to
>>> not trigger
>>> the AGC as they do,  if one could set the THR to higher level? perhaps
>>> it would stop the
>>> problem.
>>> Is it possible to increase the range of SLP and THR to move the point
>>> where S-3 or S-4
>>> signals trigger the AGC?
>>> Thanks much Eric.73 Merv K9FD/KH6
>>> __
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>>>
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Re: [Elecraft] K3 AGC Mush

[David Gilbert]

It isn't an individual rig problem, and if everyone who has noticed the 
problem sent their rig back Elecraft wouldn't get anything else done.  I 
think recreating the conditions is the relevant issue ... not variation 
from rig to rig.

It isn't difficult to figure out how close the signals need to be.  They 
need to be close enough in frequency that their sum and difference 
frequencies when mixed overlap onto the great majority of the 
originating signals.  I can fairly easily discern two keyed signals 10 
Hz apart, but put five of them within 30 Hz and the K3 turns them all 
into pudding.

The mechanics of the problem seem pretty simple to me.  The closer the 
signals are the fewer are needed to cause an overlap problem.  The 
further apart they are, the more of them are required for the mixed 
products to land on originating signals.  I'm sure someone could 
describe it mathematically, and probably already has.

Here's a point that I think a lot of people are missing, though ... the 
signals need to be pretty weak.  As someone else recently mentioned, the 
problem doesn't occur on strong signals.  If you have a high ambient 
noise level you may never even have the opportunity to notice the problem.

Dave   AB7E


On 12/4/2011 1:34 PM, Brian Alsop wrote:
> Interesting.
>
> Just a thought:
> To rule out or identify hardware problems, I wonder if someone with
> "mush" problem would be willing to loan Elecraft the offending rig?
>
> I wonder just how "exactly" on frequency guys calling from spots really
> are?  Spots are quantized in 0.1 KHz steps.  Many radios are off by 100
> Hz.  So it is easy to imagine the responders calling within a 150-200Hz
> window.  That's still a mess.
>
> 73 de Brian/K3KO
>
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Re: [Elecraft] K3 AGC Mush

[Wayne Burdick]

David Gilbert wrote:

> Here's a point that I think a lot of people are missing, though ...  
> the
> signals need to be pretty weak.  As someone else recently mentioned,  
> the
> problem doesn't occur on strong signals.  If you have a high ambient
> noise level you may never even have the opportunity to notice the  
> problem.

In some cases, I understand, turning AGC off helps with this "small- 
signal" phenomenon. When Lyle gets back from vacation, we could  
experimentally increase the range of threshold and slope settings with  
AGC on to see if that helps, too. Another thing we might want to try  
is a variation on RF GAIN that controls only the DSP gain--not the  
hardware gain. This may have less effect on the noise floor than the  
current RF gain implementation.

Also see my earlier email regarding the possibility that stronger out- 
of-DSP-passband signals could be causing problems for weak signals due  
to phantom hardware AGC modulation.

Wayne
N6KR


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Re: [Elecraft] K3 AGC Mush

[David Gilbert]

When I experience the problem the signals are all quite close ... 
probably within a 30 Hz window, but not exactly the same.  My hearing 
isn't as good as it was when I was younger (mostly high frequency loss 
above 10 KHz), but I can tell when signals are exactly the same and if 
that was the issue I'd obviously never be complaining about that.   The 
RIT on the K3 varies in 10 Hz steps and that difference is very 
noticeable to me, so it would not normally be difficult for me to 
separate a few pileup signals within that 30 Hz window if frequency was 
the only factor.

As you mentioned, signals are often very close these days.  People are 
using narrower and narrower receive filters and that puts them more 
precisely on frequency than in the past, and of course packet cluster 
spots put callers pretty close on frequency subject only to the accuracy 
of their rigs.

As I mentioned in another post, I think these are the key conditions for 
the problem:

a.  the signals need to be close enough that the children 
(sum/difference mixer products) overlap in frequency with the parents

b.  the signals need to be keyed, which makes me suspect at least some 
gain non-linearity that varies with time.  The addition of AFC-SOFT 
represented an significant improvement, but not enough.  Possibly some 
insight into this aspect of the problem might be gained by varying the 
keying speeds and observing the effect.  Even there is not a time 
non-linearity, though, having keyed signals is important.  In real life, 
keyed signals help us mentally separate signals spaced closer in 
frequency than if they were not keyed.

c.  The signals need to be weak, which makes me convinced that there is 
a gain non-linearity at the low end.  I can't really quantify just how 
weak, but I would estimate less than S-2 and it seems to get worse as 
the signals get weaker.  I have a very low ambient noise level here and 
S-1 signals are typically quite readable.  Strong signals do not cause 
the problem we are discussing here.

Hope some of this helps.

73,
Dave   AB7E



On 12/4/2011 1:31 PM, Eric Swartz WA6HHQ - Elecraft wrote:
> We actually have a 'pile-up' generator we designed that sends multiple
> cw signals. So far it has not reproduced the issue here.
>
> What is the signal spacing you are hearing this with? All -exactly- on
> the same freq? Or spread out?
>
> 73, Eric
>
> _..._
>
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Re: [Elecraft] K3 AGC Mush

[K5WA]

I really can't agree with the mush comment.  I've just returned from ZF1A
where we put almost 8000 Qs in the log over the CQWW CW weekend.  I took my
K3 and was able to evaluate it against the station's existing TS-850 since
we were M/S and rotated positions.  In my opinion, the 850 WAS mushy and the
K3 was very clear however, K6AM, our host (who is a VERY serious contester),
prefers the 850 since he has been using it for 10 years.  He also owns 4 K3s
but didn't bring them on the trip since the 850s "live" in Cayman and he
brought many pounds of other equipment.  Personal preference plays a huge
part of this discussion.  In this case, K6AM feels like his hearing is
limited to a frequency range of 6-7K while mine is still near 20K.  Maybe
that is part of the puzzle.

We regularly saw the 10 minute QSO rate meter in the 300 range and topped
400 occasionally.  I loved the way the K3 was able to plow through the
pileups which were calling us and work through them as fast as possible.
The only time I heard mush on the K3 was when we had worked down the pileup
and only had very low strength guys all calling on the same frequency (the
packet/reverse beacon spotting phenomenon).  These must have been micro-watt
QRP'ers or stations with minimal/indoor antennas.  I had my AGC on and
didn't have any time to try multiple settings but I am extremely happy with
the K3's receiver and think it is in the high end competition grade for me.

I am sending Eric my configuration file as he requested in case he is able
to find an improvement but I will be amazed if one can be found.  I've
always been extremely happy with Elecraft's commitment and motivation to
exceed expectations but they have already exceeded mine as it is.  ;-)

73,
Bob K5WA



>
This has been a very real problem for serious contesters and is the 
number one dissatisfaction I have with the K3 ... and with Elecraft.

Multiple low level CW signals within a narrow passband simply turn to 
mush and are very difficult to distinguish.  I use the bare minimum AGC 
settings in an attempt to cope since turning AGC completely off during a 
contest can be painful to both the ears and the K3 itself (as those who 
have had to replace their audio ICs can attest) but that often does not

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Re: [Elecraft] K3 AGC Mush

[Bill W4ZV]

K5WA wrote
> 
> In this case, K6AM feels like his hearing is
> limited to a frequency range of 6-7K while mine is still near 20K.  Maybe
> that is part of the puzzle.
> 

Not likely unless you can hear the 12k artifact (solved with the LPF upgrade
for the DSP).  Which reminds me...someone previously asked whether the LPF
or the full DSP was necessary.  The LPF alone solves the 12k artifact issue
(if your hearing is good enough to hear it) and the full DSP board exchange
adds extended low frequency response...mainly for ESSB.  So it really
depends on your situation.  In all honesty, for my use, I cannot tell any
difference in the 5 different K3s I've had (2 with the factory updated DSP
and 3 without). 

It certainly is a mystery why some experience the mush problem and others do
not.  Luckily I'm in the latter camp but I'm watching with interest.

73,  Bill  W4ZV


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Re: [Elecraft] K3 AGC Mush

[Wayne Burdick]

Does anyone have a clear recording of this situation using a receiver  
that *doesn't* have trouble separating the signals? Better yet, a  
recording made of both the K3 and this other receiver at the same  
time. That would really help.

tnx
Wayne
N6KR

On Dec 4, 2011, at 6:42 PM, David Gilbert wrote:

>
> When I experience the problem the signals are all quite close ...



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Re: [Elecraft] K3 AGC Mush

[ab2tc]

Hi,

Clearly, audio clips are needed if Elecraft is going to have any chance of
getting to the bottom of this. If this problem is real, somebody ought to be
able to produce objective evidence of it with comparable evidence of other
receivers not having the problem.

AB2TC - Knut


wayne burdick wrote
> 
> Does anyone have a clear recording of this situation using a receiver  
> that *doesn't* have trouble separating the signals? Better yet, a  
> recording made of both the K3 and this other receiver at the same  
> time. That would really help.
> 
> tnx
> Wayne
> N6KR
> 
> 
> 


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Re: [Elecraft] K3 AGC PLS

[Ralph Parker]

>- switch the PLS off. My experience in CW contests is that the
>PLS function will treat fast strong CW signals as pulses
>and will bypass the slow AGC for the first few dots of a signal.

AHA!  Tnx, Arie.
I have noticed this many times, and was unable to determine what caused it.

Ralph, VE7XF

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Re: [Elecraft] K3 AGC PLS

[Guy Olinger K2AV]

Yeah, but then don't key clicks punch up your slow AGC?73, Guy.

On Thu, Dec 15, 2011 at 1:53 PM, Ralph Parker  wrote:

> >- switch the PLS off. My experience in CW contests is that the
> >PLS function will treat fast strong CW signals as pulses
> >and will bypass the slow AGC for the first few dots of a signal.
>
> AHA!  Tnx, Arie.
> I have noticed this many times, and was unable to determine what caused it.
>
> Ralph, VE7XF
>
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Re: [Elecraft] K3 AGC PLS

[Arie Kleingeld PA3A]

Guy,

The K3 NoiseBlanker does a real good job here. Give it a moderate 
setting and it will work fine.

73,
Arie PA3A


Op 16-12-2011 6:04, Guy Olinger K2AV schreef:
> Yeah, but then don't key clicks punch up your slow AGC?73, Guy.
>
> On Thu, Dec 15, 2011 at 1:53 PM, Ralph Parker  wrote:
>
>>> - switch the PLS off. My experience in CW contests is that the
>>> PLS function will treat fast strong CW signals as pulses
>>> and will bypass the slow AGC for the first few dots of a signal.
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Re: [Elecraft] [K3] AGC-OFF

[Wayne Burdick]

Kevin,

This is a case where you might want to try CONFIG:AGC DCY = SOFT and/ 
or a nonzero value of AGC HLD. Either could help eliminate the need to  
ride the RF gain control, whether you run it at full clockwise or not.

73,
Wayne
N6KR



On Jun 21, 2011, at 10:12 AM, Kevin Rock wrote:

>
> I was having a hard time making out characters today during my daily  
> sked
> into the Southeast.  The QSB was a fast flutter and was chopping up  
> the
> letters badly.  I was running fast AGC and thought maybe slowing it  
> down
> may help.  It did - a little.  So I took the next logical step and  
> turn
> AGC off entirely.  The characters popped right out at me.  I just  
> rode the
> RF gain as the signal went through its slower QSB while the fast  
> flutter
> QSB did little to bother me.  AF gain was cranked to high as I  
> normally
> run it while RF gain was set to where the background QRN was  
> minimized.
> Turning off the AGC helped eliminate the fast flutter problems which  
> were
> causing me difficulties copying.
>
> This is most likely old news to many of you but I have been running AF
> gain at max and controlling volume with the RF (or IF) gain since 1960
> when I first started SWLing on my brother's Lafayette receiver.
>
> I hope this helps at least one of you drag out a new one.
>73,
>   Kevin.  KD5ONS
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Re: [Elecraft] [K3] AGC-OFF

[Dave Hachadorian]

There are two major problems with turning off the K3's AGC:

1.  There is very little dynamic headroom until the AF Limiter 
causes severe distortion on even a moderately loud signal, even 
if the AF Limiter setting is max.

2.  Never use the speaker amp with AGC turned off.  It takes just 
one dit from a loud signal to destroy the delicate speaker 
amplifier IC.  That will require a $110 factory repair, plus 
postage.


Dave Hachadorian, K6LL
Big Bear Lake, CA




-Original Message- 
From: Kevin Rock
Sent: Tuesday, June 21, 2011 10:12 AM
To: Elecraft
Subject: [Elecraft] [K3] AGC-OFF


I was having a hard time making out characters today during my 
daily sked
into the Southeast.  The QSB was a fast flutter and was chopping 
up the
letters badly.  I was running fast AGC and thought maybe slowing 
it down
may help.  It did - a little.  So I took the next logical step 
and turn
AGC off entirely.  The characters popped right out at me.  I just 
rode the
RF gain as the signal went through its slower QSB while the fast 
flutter
QSB did little to bother me.  AF gain was cranked to high as I 
normally
run it while RF gain was set to where the background QRN was 
minimized.
Turning off the AGC helped eliminate the fast flutter problems 
which were
causing me difficulties copying.

This is most likely old news to many of you but I have been 
running AF
gain at max and controlling volume with the RF (or IF) gain since 
1960
when I first started SWLing on my brother's Lafayette receiver.

I hope this helps at least one of you drag out a new one.
73,
   Kevin.  KD5ONS
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Re: [Elecraft] [K3] AGC-OFF

[Kevin Rock]

I never use the speaker and I ride the RF gain.  When I hear the signal  
rising I can catch it in time to avoid limiting.  However, I only use this  
method when the QSB is a fast flutter which causes me problems.  When the  
QSB is simply a slow up and down wave I'll use AGC-F which is fine.  This  
morning I had both rapid and slow QSB.  The rapid QSB was the problem  
while the slow QSB was easily dealt with by riding the RF gain.
Kevin.  KD5ONS




On Tue, 21 Jun 2011 19:24:03 -0700, Dave Hachadorian  wrote:

> There are two major problems with turning off the K3's AGC:
>
> 1.  There is very little dynamic headroom until the AF Limiter causes  
> severe distortion on even a moderately loud signal, even if the AF  
> Limiter setting is max.
>
> 2.  Never use the speaker amp with AGC turned off.  It takes just one  
> dit from a loud signal to destroy the delicate speaker amplifier IC.   
> That will require a $110 factory repair, plus postage.
>
>
> Dave Hachadorian, K6LL
> Big Bear Lake, CA
>
>
>
>
> -Original Message- From: Kevin Rock
> Sent: Tuesday, June 21, 2011 10:12 AM
> To: Elecraft
> Subject: [Elecraft] [K3] AGC-OFF
>
>
> I was having a hard time making out characters today during my daily sked
> into the Southeast.  The QSB was a fast flutter and was chopping up the
> letters badly.  I was running fast AGC and thought maybe slowing it down
> may help.  It did - a little.  So I took the next logical step and turn
> AGC off entirely.  The characters popped right out at me.  I just rode  
> the
> RF gain as the signal went through its slower QSB while the fast flutter
> QSB did little to bother me.  AF gain was cranked to high as I normally
> run it while RF gain was set to where the background QRN was minimized.
> Turning off the AGC helped eliminate the fast flutter problems which were
> causing me difficulties copying.
>
> This is most likely old news to many of you but I have been running AF
> gain at max and controlling volume with the RF (or IF) gain since 1960
> when I first started SWLing on my brother's Lafayette receiver.
>
> I hope this helps at least one of you drag out a new one.
> 73,
>Kevin.  KD5ONS
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Re: [Elecraft] [K3] AGC-OFF

[Ron D'Eau Claire]

Saving that $110 plus postage is one advantage of being a "solder jockey" -
but I've never managed to damage one of those IC's with a brief signal no
matter how loud. They saturate, keeping any voltage spikes inside the limits
they can withstand. 

What will kill one, IMX, is a sustained saturated signal (for several
minutes) that eventually causes the chip to overheat from excessive power
dissipation. 

Big Bear Lake ought to be beautiful this time of the year, Dave. (I was
raised in Redlands, down below you in the San Bernardino Valley.) But so is
the central Oregon coast this time of the year :-)

73, 

Ron AC7AC

-Original Message-
2.  Never use the speaker amp with AGC turned off.  It takes just 
one dit from a loud signal to destroy the delicate speaker 
amplifier IC.  That will require a $110 factory repair, plus 
postage.


Dave Hachadorian, K6LL
Big Bear Lake, CA

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Re: [Elecraft] [K3] AGC-OFF

[Kevin Rock]

I just realized I picked up my operating traits of always wearing  
headphones and riding the RF gain 50 years ago.  Shocked me to think I  
have been listening to shortwave for so very long!  I may be getting old  
:)  But I did learn them from a WWII radio man while wearing his vintage  
phones.  All that Marine training sticks after all these years.
Kevin.




On Tue, 21 Jun 2011 20:22:36 -0700, Ron D'Eau Claire  wrote:

> Saving that $110 plus postage is one advantage of being a "solder  
> jockey" -
> but I've never managed to damage one of those IC's with a brief signal no
> matter how loud. They saturate, keeping any voltage spikes inside the  
> limits
> they can withstand.
>
> What will kill one, IMX, is a sustained saturated signal (for several
> minutes) that eventually causes the chip to overheat from excessive power
> dissipation.
>
> Big Bear Lake ought to be beautiful this time of the year, Dave. (I was
> raised in Redlands, down below you in the San Bernardino Valley.) But so  
> is
> the central Oregon coast this time of the year :-)
>
> 73,
>
> Ron AC7AC
>
> -Original Message-
> 2.  Never use the speaker amp with AGC turned off.  It takes just
> one dit from a loud signal to destroy the delicate speaker
> amplifier IC.  That will require a $110 factory repair, plus
> postage.
>
>
> Dave Hachadorian, K6LL
> Big Bear Lake, CA
>


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Re: [Elecraft] [K3] AGC-OFF

[Barry N1EU]

Dave Hachadorian wrote:
> 
> There are two major problems with turning off the K3's AGC:
> 
> 1.  There is very little dynamic headroom until the AF Limiter 
> causes severe distortion on even a moderately loud signal, even 
> if the AF Limiter setting is max.
> 

That's not necessarily true, although probably true with most headphones on
the market.  Assuming non-impaired hearing, the effective dynamic range will
be highly dependent on your baseline (ambient) noise level and subsequent
gain settings.  That's why K3NA strongly emphasized the need for high
isolation headphone schemes in his original treatise on AGC-less contesting. 
The higher the isolation, the greater the ability to hear low audio levels,
the lower the needed gain setting, and the greater the dynamic range before
onset of distortion/clipping/painfully Loud levels.  With the highest
isolation schemes, distortion/clipping rarely occurs while the weakest
signals are still rendered audible.  I know that in-ear type phones ("ear
buds") can be very successful in this regard, but long term comfort is
suspect.  Every over-the-ear headphone I've tried so far that was touted as
"high" or "extreme" isolation didn't quite deliver the degree of isolation
that was hoped for, and weren't any better than my Sennheiser HD-280.  I'm
still searching for more isolation without compromising comfort.

73, Barry N1EU


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Re: [Elecraft] [K3] AGC-OFF

[Eric Scace K3NA]

Another factor at play is the sensitivity/efficiency of the headset.  For a 
given power level, different headsets will deliver different sound levels to 
the 
ear.

In the case of my in-ear monitors, I found a significant amount of 
attenuation of the K3's headphone output was needed to:
1)  Suppress the low-level broadband hiss of the K3's audio output 
amplifier 
to a level where I could not hear it.
2)  Keep the maximum output level of the K3 (the point where the AF limiter 
kicks in) just below the "ouch" level for my ears.

A different set of headphones required much less attenuation (5-10 dB) to 
meet (2) above and the hiss couldn't be heard even without the attenuator.

A less efficient set of headphones might cause the operator to think the AF 
limiter was kicking in at way too low a level.  In this case, that pair of 
headphones might need a bit of audio amplification between the K3 and the 
earpiece.

Regarding Barry's note about long-term comfort:  custom-fitted earpieces 
for 
in ear monitors worked for me... but this is a more costly solution (but bought 
only once - hi!).  I can wear the in ear monitors for 48 hours without even 
thinking about it.  I could never do that with ordinary headphones.  But 
everyone is different!

In ear monitors that do not use custom-fitted ear pieces (i.e., use the 
rubbery or foam ear plugs) exert some pressure on the sides of the ear canal 
and 
can be annoying after 6-8 hours... at least for me.

— Eric K3NA

p.s.:  The contesting wiki has the information to which Barry referred:


on 2011 Jun 22 07:03 Barry N1EU said the following:
> Dave Hachadorian wrote:
>> There are two major problems with turning off the K3's AGC:
>>
>> 1.  There is very little dynamic headroom until the AF Limiter
>> causes severe distortion on even a moderately loud signal, even
>> if the AF Limiter setting is max.
>>
> That's not necessarily true, although probably true with most headphones on
> the market.  Assuming non-impaired hearing, the effective dynamic range will
> be highly dependent on your baseline (ambient) noise level and subsequent
> gain settings.  That's why K3NA strongly emphasized the need for high
> isolation headphone schemes in his original treatise on AGC-less contesting.
> The higher the isolation, the greater the ability to hear low audio levels,
> the lower the needed gain setting, and the greater the dynamic range before
> onset of distortion/clipping/painfully Loud levels.  With the highest
> isolation schemes, distortion/clipping rarely occurs while the weakest
> signals are still rendered audible.  I know that in-ear type phones ("ear
> buds") can be very successful in this regard, but long term comfort is
> suspect.  Every over-the-ear headphone I've tried so far that was touted as
> "high" or "extreme" isolation didn't quite deliver the degree of isolation
> that was hoped for, and weren't any better than my Sennheiser HD-280.  I'm
> still searching for more isolation without compromising comfort.
>
> 73, Barry N1EU
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Re: [Elecraft] [K3] AGC-OFF

[Ron D'Eau Claire]

Years ago the standard "headphone" was a magnetic transducer using a strong 
metal disk diaphragm. There was almost no way one was going to damage them by 
over-driving them.

Most professional radiomen (CW operators) wore the 'phones on their head in 
front of their ears, not over the ears themselves. That way the radioman could 
carry on a conversation while copying messages, either in their head or on a 
"mill" (typewriter) and his/her ears were never at risk. In a very marginal, 
weak-signal situation the radioman might move one headphone back onto his ear 
briefly.   

Also, all the concern over a 'sine wave' tone is a modern affectation that 
still gets a chuckle out of me and many other OTs. Professional CW operators 
and Hams alike seldom cared if the tone they heard was a sine wave, a square 
wave or even some odd-ball sawtooth or triangular waveform. For many, many 
years my personal favorite sidetone monitor was an RF-activated sawtooth wave 
generator. I operated some gear in professional/military installations which 
the "sidetone" heard while sending was no tone at all, just a confused bunch of 
bloops, squeals and blasts of hum from a monitor receiver. No one thought 
anything of it. 

The bottom line is expectations change. Back then we thought nothing of taking 
five or ten minutes to tune up on a different band. Many Hams built their 
stations to operate on only one band.

And some of us are still out there, Hi! 

Ron AC7AC


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Re: [Elecraft] [K3] AGC-OFF

[Rick Dettinger]

My introduction to Morse code was in 1955.  Our Boy Scout Troop used  
an Instrograph to teach the code for a merit badge.  Its been 55 years  
and I still consider the note from that machine to be the gold  
standard for code practice oscillators.  I don't know if it was a pure  
sine wave, but it was music to my ears.  I know that real music is  
definitely not a sine wave.  I suspect that spark was about as far as  
its possible to get from a pure sine wave!


73,
Rick Dettinger   K7MW


>
> Also, all the concern over a 'sine wave' tone is a modern  
> affectation that still gets a chuckle out of me and many other OTs.  
> Professional CW operators and Hams alike seldom cared if the tone  
> they heard was a sine wave, a square wave or even some odd-ball  
> sawtooth or triangular waveform. For many, many years my personal  
> favorite sidetone monitor was an RF-activated sawtooth wave  
> generator. I operated some gear in professional/military  
> installations which the "sidetone" heard while sending was no tone  
> at all, just a confused bunch of bloops, squeals and blasts of hum  
> from a monitor receiver. No one thought anything of it.
>
> The bottom line is expectations change. Back then we thought nothing  
> of taking five or ten minutes to tune up on a different band. Many  
> Hams built their stations to operate on only one band.
>
> And some of us are still out there, Hi!
>
> Ron AC7AC
>
>

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Re: [Elecraft] K3 AGC usage question

[Lyle Johnson]

Mike wrote:
> When I turn the AGC off, my audio sounds like the speaker cone is torn, 
> either the external speakers or phones. It's very difficult to describe.

CONFIG: AF LIM is used to hard limit the audio level so you don't get 
"blasted" by a strong signal when you have the gain cranked up to hear a 
weak one with AGC OFF.   This is only in effect with AGC OFF.

73,

Lyle KK7P
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Re: [Elecraft] K3 AGC usage question

[Mike]

AF LIM is set to 12. Shouldn't that be enough?

I wouldn't characterize the signal as strong. It doesn't make any 
difference what the AF gain is, as  long as it's loud enough to hear. 
Even the beep when I turn AGC back on is raspy.

I'm not trying to be argumentative, just trying to get a handle on 
whether it's pilot error or something else. And how to fix it either way.

Mike

Lyle Johnson wrote:
> Mike wrote:
>> When I turn the AGC off, my audio sounds like the speaker cone is 
>> torn, either the external speakers or phones. It's very difficult to 
>> describe.
>
> CONFIG: AF LIM is used to hard limit the audio level so you don't get 
> "blasted" by a strong signal when you have the gain cranked up to hear 
> a weak one with AGC OFF.   This is only in effect with AGC OFF.
>
> 73,
>
> Lyle KK7P
>


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Re: [Elecraft] K3 AGC usage question

[Mike]

Thanks, Steve.

I ran it from 12 up to 24. That seems to have cleaned it up FB. I had in 
my mind it worked the other way.

73, Mike

Steve Ellington wrote:
> Go into the Config menu and crank up the AF Limit some. It's working 
> correctly but just turned up too high.
>
> Steve
> N4LQ
> n...@carolina.rr.com
> - Original Message - From: "Mike" 
> To: 
> Sent: Sunday, January 10, 2010 10:25 AM
> Subject: [Elecraft] K3 AGC usage question
>
>
>> When I turn the AGC off, my audio sounds like the speaker cone is torn,
>> either the external speakers or phones. It's very difficult to describe.
>>
>> I made a .wav file using Windows recorder, with the mic held in front to
>> my external speakers. It's a CW signal, with the 250Hz roofing filter.
>> It starts with AGC on, then off then on again. It's roughly an S4 signal
>> and S4 noise. I reduced the RF gain to aboyt 3 o'clock.
>>
>> If someone can tell me how to make a better recording. please do.
>>
>> Listen here. http://nf4l.com/k3agc.htm
>>
>> Am I doing something wrong, or do I have a rig problem?
>>
>> Thanks,
>>
>> Mike NF4L
>>
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>
> 
>  
>
>
>
>
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> Checked by AVG - www.avg.com
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Re: [Elecraft] K3: AGC THR/SLP

[Don Wilhelm]

  Ralph,

I am pleased to hear that I could be of help to you.  Enjoy your K3.

73,
Don W3FPR

On 10/8/2010 11:58 PM, Ralph Parker wrote:
>> Let's study what the AGC SLP and AGC THR settings do
>> and try to relate them to the perception that the K3 is noisy.
> Tnx, Don.
> I read your website item, tried your AGC settings, and even fooled around
> with them a bit, listening to a busy night on 40m CW. I didn't realize that
> I could hear the effect of the adjustments as I made them, and that was a
> help.
> I'm pleased with the results - the changes even made quite a difference to
> my up-to-now lack of audio via the speaker!
>
> I guess some of us need a little more 'convincing' than others.
> Tnx for sticking with us.
>
> VE7XF
>
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Re: [Elecraft] K3 AGC dead spot

[Vic K2VCO]

My guess is that you need to do the RF Gain Calibration procedure with the K3 
utility. If 
you have an XG1 or XG2 you can use it as a calibrated source, or if not you can 
tell the 
utility to use the factory default settings.

On 10/20/2010 8:13 PM, Mike wrote:
> Tonight I noticed that from about 2:00 to 2:30 on the RF gain encoder, the 
> receiver
> goes dead. It's not dependent on the THR or SLP settings which I adjusted to 
> match
> some advice given here short time past.
>
> I also realized my S-meter doesn't rise as the RF gain is reduced. I like 
> that, but I
> don't know how it got that way. :-P
>
> I have the latest firmware.
>
> It's not really a big deal, but is is puzzling.
>
> 73, Mike NF4L
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-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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Re: [Elecraft] K3 AGC dead spot

[Greg]

  Also check you CONFIG SMTR MD.  May be on ABS vice NOR??

73
Greg


On 10/20/2010 8:50 PM, Vic K2VCO wrote:
> My guess is that you need to do the RF Gain Calibration procedure with the K3 
> utility. If
> you have an XG1 or XG2 you can use it as a calibrated source, or if not you 
> can tell the
> utility to use the factory default settings.
>
> On 10/20/2010 8:13 PM, Mike wrote:
>> Tonight I noticed that from about 2:00 to 2:30 on the RF gain encoder, the 
>> receiver
>> goes dead. It's not dependent on the THR or SLP settings which I adjusted to 
>> match
>> some advice given here short time past.
>>
>> I also realized my S-meter doesn't rise as the RF gain is reduced. I like 
>> that, but I
>> don't know how it got that way. :-P
>>
>> I have the latest firmware.
>>
>> It's not really a big deal, but is is puzzling.
>>
>> 73, Mike NF4L
>> __
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Re: [Elecraft] K3 AGC dead spot

[Mike]

Thanks, Vic.

Per Dale's suggestion I did a calibration using factory defaults, and the dead 
spot 
is gone, and the S-meter is back to rising with a decrease of RF gain. Dagnab 
it.

73, Mike NF4L

On 10/20/2010 11:50 PM, Vic K2VCO wrote:
> My guess is that you need to do the RF Gain Calibration procedure with the K3 
> utility. If
> you have an XG1 or XG2 you can use it as a calibrated source, or if not you 
> can tell the
> utility to use the factory default settings.
>
> On 10/20/2010 8:13 PM, Mike wrote:
>> Tonight I noticed that from about 2:00 to 2:30 on the RF gain encoder, the 
>> receiver
>> goes dead. It's not dependent on the THR or SLP settings which I adjusted to 
>> match
>> some advice given here short time past.
>>
>> I also realized my S-meter doesn't rise as the RF gain is reduced. I like 
>> that, but I
>> don't know how it got that way. :-P
>>
>> I have the latest firmware.
>>
>> It's not really a big deal, but is is puzzling.
>>
>> 73, Mike NF4L


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Re: [Elecraft] K3 AGC dead spot

[Guy Olinger K2AV]

The thing to note here, this ain't your daddy's analog radio, the only
actual "stage gain" adjustments you have are ATT and PRE.  The rest is
all in the numbers, as the front panel knobs are just numerical advice
to the firmware.  They don't directly control anything.

What needs to happen is a calibration of what voltage sent to the
variable 8 MHz stage produces a specific number out of the 15 kHz
analog-to-digital converter, etc, and exactly what stage gain change
occurs when PRE enabled, ATT enabled.

Also note here that the PRE and ATT button is also just advice to the
firmware.  The button does not directly control a circuit, as opposed
to a DPDT switch carrying RF on its terminals that literally removes a
PRE from the circuit.  The in and out is done by a one or zero bit
state from the MCU, converted to a switching voltage which biases
various diodes which change the signal path in the RX.

All of this stuff gets tabled up in the firmware, which constantly
consults it to set levels in the output and optimize IF gain into the
15 kHz ADC.  If the numbers in the table are goofy, so will the
behavior be goofy.

Better to calibrate the K3 on a signal source (over the years, the
XG-2 will pay for itself, over and over) and have it right.

If you bought the radio assembled, this was done for you when you got
it.  If you assembled it, needs doing.

Personally, sometimes I think the tables get hosed by ??? and needs
redoing. Done it a couple of times to restore normal function and have
no clue what happened to make it that way.

73, Guy.

On Thu, Oct 21, 2010 at 6:41 AM, Mike  wrote:
>
> Thanks, Vic.
>
> Per Dale's suggestion I did a calibration using factory defaults, and the 
> dead spot
> is gone, and the S-meter is back to rising with a decrease of RF gain. Dagnab 
> it.
>
> 73, Mike NF4L
>
> On 10/20/2010 11:50 PM, Vic K2VCO wrote:
>> My guess is that you need to do the RF Gain Calibration procedure with the 
>> K3 utility. If
>> you have an XG1 or XG2 you can use it as a calibrated source, or if not you 
>> can tell the
>> utility to use the factory default settings.
>>
>> On 10/20/2010 8:13 PM, Mike wrote:
>>> Tonight I noticed that from about 2:00 to 2:30 on the RF gain encoder, the 
>>> receiver
>>> goes dead. It's not dependent on the THR or SLP settings which I adjusted 
>>> to match
>>> some advice given here short time past.
>>>
>>> I also realized my S-meter doesn't rise as the RF gain is reduced. I like 
>>> that, but I
>>> don't know how it got that way. :-P
>>>
>>> I have the latest firmware.
>>>
>>> It's not really a big deal, but is is puzzling.
>>>
>>> 73, Mike NF4L
>
>
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Re: [Elecraft] K3 AGC dead spot

[Mike]

I understand that the knob labeled RF doesn't really control RF gain, but since 
Elecraft labeled it that way, I think it's better to reference it that way.

I have an XG2, and had done the RF gain calibration using it. Dale recommended 
doing 
it using the factory defaults. I'm waiting to hear back from him why.

It's a kit, just a tad over a year old, with all available mods.

The mechanism by which the tables may get hosed is the same principle which 
makes 
them work. HPFM. (HocusPocusFreakyMagic) :-D .

73, Mike NF4L

On 10/21/2010 7:42 AM, Guy Olinger K2AV wrote:
> The thing to note here, this ain't your daddy's analog radio, the only
> actual "stage gain" adjustments you have are ATT and PRE.  The rest is
> all in the numbers, as the front panel knobs are just numerical advice
> to the firmware.  They don't directly control anything.
>
> What needs to happen is a calibration of what voltage sent to the
> variable 8 MHz stage produces a specific number out of the 15 kHz
> analog-to-digital converter, etc, and exactly what stage gain change
> occurs when PRE enabled, ATT enabled.
>
> Also note here that the PRE and ATT button is also just advice to the
> firmware.  The button does not directly control a circuit, as opposed
> to a DPDT switch carrying RF on its terminals that literally removes a
> PRE from the circuit.  The in and out is done by a one or zero bit
> state from the MCU, converted to a switching voltage which biases
> various diodes which change the signal path in the RX.
>
> All of this stuff gets tabled up in the firmware, which constantly
> consults it to set levels in the output and optimize IF gain into the
> 15 kHz ADC.  If the numbers in the table are goofy, so will the
> behavior be goofy.
>
> Better to calibrate the K3 on a signal source (over the years, the
> XG-2 will pay for itself, over and over) and have it right.
>
> If you bought the radio assembled, this was done for you when you got
> it.  If you assembled it, needs doing.
>
> Personally, sometimes I think the tables get hosed by ??? and needs
> redoing. Done it a couple of times to restore normal function and have
> no clue what happened to make it that way.
>
> 73, Guy.
>
> On Thu, Oct 21, 2010 at 6:41 AM, Mike  wrote:
>> Thanks, Vic.
>>
>> Per Dale's suggestion I did a calibration using factory defaults, and the 
>> dead spot
>> is gone, and the S-meter is back to rising with a decrease of RF gain. 
>> Dagnab it.
>>
>> 73, Mike NF4L
>>
>> On 10/20/2010 11:50 PM, Vic K2VCO wrote:
>>> My guess is that you need to do the RF Gain Calibration procedure with the 
>>> K3 utility. If
>>> you have an XG1 or XG2 you can use it as a calibrated source, or if not you 
>>> can tell the
>>> utility to use the factory default settings.
>>>
>>> On 10/20/2010 8:13 PM, Mike wrote:
 Tonight I noticed that from about 2:00 to 2:30 on the RF gain encoder, the 
 receiver
 goes dead. It's not dependent on the THR or SLP settings which I adjusted 
 to match
 some advice given here short time past.

 I also realized my S-meter doesn't rise as the RF gain is reduced. I like 
 that, but I
 don't know how it got that way. :-P

 I have the latest firmware.

 It's not really a big deal, but is is puzzling.

 73, Mike NF4L
>>
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Re: [Elecraft] K3 AGC dead spot

[Don Wilhelm]

  Mike,

Recently a bug was found with the RF Gain Calibration routine in K3 
Utility did not properly save the new data.
If you were not using the very latest K3 Utility, that would explain 
many anomalies.  Moral - download the latest K3 Utility and try again.

73,
Don W3FPR

On 10/21/2010 8:53 AM, Mike wrote:
> I understand that the knob labeled RF doesn't really control RF gain, but 
> since
> Elecraft labeled it that way, I think it's better to reference it that way.
>
> I have an XG2, and had done the RF gain calibration using it. Dale 
> recommended doing
> it using the factory defaults. I'm waiting to hear back from him why.
>
> It's a kit, just a tad over a year old, with all available mods.
>
> The mechanism by which the tables may get hosed is the same principle which 
> makes
> them work. HPFM. (HocusPocusFreakyMagic) :-D .
>
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Re: [Elecraft] K3 AGC dead spot

[Mike]

Don,

I have 1.3.10.15, and in fact had done a calibration using the XG2 with it. 
Still 
waiting to hear why Dale recommended factory defaults. He should be getting to 
the 
office soon.

I assume (yeah I know) when using the XG2, it doesn't matter which of the 3 
freqs I 
use.

73, Mike NF4L

On 10/21/2010 9:18 AM, Don Wilhelm wrote:
>  Mike,
>
> Recently a bug was found with the RF Gain Calibration routine in K3 Utility 
> did not 
> properly save the new data.
> If you were not using the very latest K3 Utility, that would explain many 
> anomalies.  Moral - download the latest K3 Utility and try again.
>
> 73,
> Don W3FPR
>
> On 10/21/2010 8:53 AM, Mike wrote:
>> I understand that the knob labeled RF doesn't really control RF gain, but 
>> since
>> Elecraft labeled it that way, I think it's better to reference it that way.
>>
>> I have an XG2, and had done the RF gain calibration using it. Dale 
>> recommended doing
>> it using the factory defaults. I'm waiting to hear back from him why.
>>
>> It's a kit, just a tad over a year old, with all available mods.
>>
>> The mechanism by which the tables may get hosed is the same principle which 
>> makes
>> them work. HPFM. (HocusPocusFreakyMagic) :-D .
>>
>


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Re: [Elecraft] K3 AGC dead spot

[Chuck Shefflette]

Guy,

Actually, the RF gain control does have an affect on the analog, as does the
AGC. There are 2 types of AGC in the K3, the first is the more obvious that
is controlled by the AGC Slow/Fast/Off and the second is a hardware AGC that
protects the A/D converters. The "normal" AGC is summed with the hardware
AGC to control the gain of the IF amplifier that immediately precedes the
2nd mixer stage. The "normal" AGC is also more than likely used in some of
the DSP calculations but that is a little less obvious to the outside
observer.

The Pre and Att controls, on the other hand, have real effects on the
electronics. The Pre is used to switch the PIN diodes that control the
signal path through our around the 11 dB RF Pre-amplifer stage. The Att
switches relay K10 which physically switches in and out a 10 dB attenuator
circuit.

Granted, all these controls result from switch presses (the Att/Pre) or the
A/D results of the RF gain pot that are decoded by the MCU and transmitted
to the appropriate control circuits, but they do really have an affect on
the radio's operation, not just in the software.

However, you are right when you say this isn't a traditional analog radio,
at least beyond the 2nd IF stage!

73,
Chuck, AA3CS
K3 #s 4072 & 4407


Guy, K2AV wrote:
> 
> The thing to note here, this ain't your daddy's analog radio, the only
> actual "stage gain" adjustments you have are ATT and PRE.  The rest is
> all in the numbers, as the front panel knobs are just numerical advice
> to the firmware.  They don't directly control anything.
> 
> ...
> 

-
73 - Chuck, AA3CS
-- 
View this message in context: 
http://elecraft.365791.n2.nabble.com/K3-AGC-dead-spot-tp5657353p5660211.html
Sent from the [K3] mailing list archive at Nabble.com.
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Re: [Elecraft] K3 AGC Settings Tutorial

[AD6XY]

Thanks for the explanation. As you say, noise levels differ between bands and
over time E.g. 80m in Summer compared to Winter or HF versus 50MHz and
higher bands via a transverter. Does the AGC setting apply per band or does
it cover all bands?

AGC also depends on mode, CW vs SSB bandwidths. Again, does it differ?

If so there will be an awful lot of tweeking needed for all possible
combinations.

73 Mike


Lyle Johnson wrote:
> 
> Note: Different bands and different days have different amounts of 
> noise.  A noise QRN-filled summer noise level is very different than a 
> quiet winter evening's noise level.  The AGC doesn't know the 
> difference, so it is up to you to change things if you desire different 
> thresholds on a seasonal basis.
> 

-- 
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Re: [Elecraft] K3 AGC Settings Tutorial

[Lyle Johnson]

Thanks for the explanation. As you say, noise levels differ between bands and
over time E.g. 80m in Summer compared to Winter or HF versus 50MHz and
higher bands via a transverter. Does the AGC setting apply per band or does
it cover all bands?


AGC is AGC. It is not per band, it is per radio :-)


AGC also depends on mode, CW vs SSB bandwidths. Again, does it differ?


Use AGC OFF | FAST | SLOW

Most people prefer FAST for CW and SLOW for SSB.


If so there will be an awful lot of tweeking needed for all possible
combinations.


I do not know of a radio with per band AGC settings, or per season. 
Most radios don't let you adjust the threshold or slope -- or the decay 
rate of FAST and SLOW.


With the K3 we allow you to tailor the AGC; we don't require that you 
tailor it.


73,

Lyle KK7P

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RE: [Elecraft] K3 AGC Settings Tutorial

[4CX250B]

*
AGC is AGC. It is not per band, it is per radio :-)

I do not know of a radio with per band AGC settings, or per season.
Most radios don't let you adjust the threshold or slope -- or the decay
rate of FAST and SLOW.
With the K3 we allow you to tailor the AGC; we don't require that you
tailor it.

73,

Lyle KK7P
*

It is true that the AGC pertains to the radio and not the band, but the optimal 
AGC threshold setting does vary by band.  On 80m, for example, I set the AGC 
threshold on my Ten-Tec Orion at about 20uV.  On 10m, where the noise level is 
very low, I set it at 0.5uV. The Orion, incidentally, has fast, medium, and 
slow AGC settings, plus a custom "prog" setting, and one can set the threshold, 
decay rate and hang time independently for each speed. It is possible to spend 
hours fiddling with the Orion's AGC settings.

73,

Jim W8ZR



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Re: [Elecraft] K3 AGC Settings Tutorial

[Tom W8JI]

It is true that the AGC pertains to the radio and not the 
band, but the optimal AGC threshold setting does vary by 
band.  On 80m, for example, I set the AGC threshold on my 
Ten-Tec Orion at about 20uV.  On 10m, where the noise level 
is very low, I set it at 0.5uV. The Orion, incidentally, has 
fast, medium, and slow AGC settings, plus a custom "prog" 
setting, and one can set the threshold, decay rate and hang 
time independently for each speed. It is possible to spend 
hours fiddling with the Orion's AGC settings.>>


One of the reasons you have to change it so much is any AGC 
that has no effect at all until a threshold and then tips in 
all at once is always critical to adjust. A good AGC system 
has a slope rather than a hard threshold with no AGC at all 
below a point, and then hard AGC after that point that 
clamps the volume to one level.


At quiet locations the dominant noise is propagated via 
skywave just like the desired signals. This means the noise 
floor varies greatly with direction depending on propagation 
or even the time of day. On the same band in different 
directions the noise floor can vary 10 or 20 dB. This 
requires constant adjustment of AGC threshold with any AGC 
that tips in fully at a threshold.


AGC systems with a slope don't exaggerate the problem of 
noise level changes and they don't "muddy" the signals into 
one constant level or no AGC at all.


When I solid stated my R4C's I built a new AGC circuit. I 
put a lot of gain in the AGC, there was very little audio 
level change with input signal level change. On the bench it 
was nearly perfect, once the AGC started working everything 
stayed at nearly the same audio level. I worked to make it 
have flat audio level with varying signal levels, textbook 
perfect AGC.


Everyone hated it. It required constant riding of RF gain. 
It made weak DX stations near noise floor muddy up or 
vanish, and it was impossible to sort signals close in pitch 
in pileups.


Decreasing the gain in the AGC circuit cured it, and it was 
no longer necessary to ride the RF gain (same as adjusting 
AGC threshold).


The K3 has an AGC SLP adjustment that cures this problem. I 
was delighted to see the people at Elecraft included an AGC 
slope adjustment, and that it works to make the AGC have 
that "analog" sound operators here like for handling pileups 
and for weak signals in rough noise. Unless you have an old 
analog AGC system the slope adjustment is a "must have" 
requirement. Especially for people who work pileups or work 
DX that is in and out of rough noise like static crashes.


Although I just started using the K3, I really like the AGC 
system so far. That's in contrast to other digital AGC 
systems I quickly learned to *dislike*. Low band DXers or 
contesting people will really like the "slope adjustment" 
feature.


73 Tom




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Re: [Elecraft] K3 AGC strange behavior

[dj7mgq]

Hallo Klaus,

just saw, that when you switch off AGC, the S-meter and receiver   
Gain will stay at the level where it was at the moment when you   
switch off agc - for example noise at S4,  switch off AGC  - S-meter  
 will still show S4 and gain is also reduced, switching off antenna   
before AGC off and antenna on again will show S0 and full receiver   
gain...


This sounds like something for a CC to <[EMAIL PROTECTED]>,  
which, afaik, is where Elecraft would like to receive bug reports.


Thanks for heads up,

vy 73 de toby

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Re: [Elecraft] K3 AGC strange behavior

[Ken K3IU]

Same behavior here with #202 and latest firmware.
73,
Ken K3IU

[EMAIL PROTECTED] wrote:

Hallo Klaus,

just saw, that when you switch off AGC, the S-meter and receiver  
Gain will stay at the level where it was at the moment when you  
switch off agc - for example noise at S4,  switch off AGC  - S-meter 
 will still show S4 and gain is also reduced, switching off antenna  
before AGC off and antenna on again will show S0 and full receiver  
gain...


This sounds like something for a CC to <[EMAIL PROTECTED]>, 
which, afaik, is where Elecraft would like to receive bug reports.


Thanks for heads up,

vy 73 de toby

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Re: [Elecraft] K3 AGC strange behavior

[Gil Cross]

   The folks at Elecraft are aware of this behavior.
   73  Gil  K8EAG


- Original Message - 
From: "Ken K3IU" <[EMAIL PROTECTED]>

To: <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>; ; <[EMAIL PROTECTED]>
Sent: Friday, January 18, 2008 6:49 AM
Subject: Re: [Elecraft] K3 AGC strange behavior



Same behavior here with #202 and latest firmware.
73,
Ken K3IU

[EMAIL PROTECTED] wrote:

Hallo Klaus,

just saw, that when you switch off AGC, the S-meter and receiver  
Gain will stay at the level where it was at the moment when you  
switch off agc - for example noise at S4,  switch off AGC  - S-meter 
 will still show S4 and gain is also reduced, switching off antenna  
before AGC off and antenna on again will show S0 and full receiver  
gain...


This sounds like something for a CC to <[EMAIL PROTECTED]>, 
which, afaik, is where Elecraft would like to receive bug reports.


Thanks for heads up,

vy 73 de toby

___>

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Re: [Elecraft] [K3] AGC White Paper

[Bill Frantz]

Thanks Al. A very useful paper.

Now to use SLP=15 for digital, where I want the AtoD to not have 
to deal with a big range, while using something with more 
dynamic range for voice/CW.


73 Bill AE6JV

On 3/6/17 at 9:50 PM, alor...@sbcglobal.net (Al Lorona) wrote:

I spent a little bit of time this weekend and put together yet 
another K3 AGC (YAKA) "white paper" to put some measurements 
and discussion of the results down in the hope that others may 
benefit. Maybe it'll help folks understand AGC better by 
demystifying some of the K3 idiosyncrasies. I hope it makes you 
think about a few things in a way that maybe never occurred to 
you. I put the document in my Dropbox at the following link:



https://www.dropbox.com/s/drfujqupr4pcet3/Getting%20the%20Most%20Out%20of%20K3%20AGC%20System.pdf?dl=
0


I'll leave the file there for several days in case any of y'all are interested.


---
Bill Frantz| Security is like Government  | Periwinkle
(408)356-8506  | services. The market doesn't | 16345 
Englewood Ave
www.pwpconsult.com | want to pay for them.| Los Gatos, 
CA 95032


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Re: [Elecraft] [K3] AGC White Paper

[Cady, Fred]

Very nice Al  Thanks.

73,

Fred KE7X




From: Elecraft  on behalf of Al Lorona 

Sent: Sunday, March 5, 2017 10:50 PM
To: Elecraft Reflector
Subject: [Elecraft] [K3] AGC White Paper

I spent a little bit of time this weekend and put together yet another K3 AGC 
(YAKA) "white paper" to put some measurements and discussion of the results 
down in the hope that others may benefit. Maybe it'll help folks understand AGC 
better by demystifying some of the K3 idiosyncrasies. I hope it makes you think 
about a few things in a way that maybe never occurred to you. I put the 
document in my Dropbox at the following link:


https://www.dropbox.com/s/drfujqupr4pcet3/Getting%20the%20Most%20Out%20of%20K3%20AGC%20System.pdf?dl=0


I'll leave the file there for several days in case any of y'all are interested.

73,

Al  W6LX
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Re: [Elecraft] [K3] AGC White Paper

[Sverre Holm (LA3ZA)]

Very nice report - thanks!



-
Sverre, LA3ZA

K2 #2198, K3 #3391,
LA3ZA Blog: http://la3za.blogspot.com,
LA3ZA Unofficial Guide to K2 modifications: 
http://la3za.blogspot.com/p/la3za-unofficial-guide-to-elecraft-k2.html
--
View this message in context: 
http://elecraft.365791.n2.nabble.com/K3-AGC-White-Paper-tp7627649p7627677.html
Sent from the Elecraft mailing list archive at Nabble.com.
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Re: [Elecraft] [K3] AGC White Paper

[Wes Stewart]

In Al's very nicely done paper he has this paragraph:

   "The purpose of Automatic Gain Control (AGC) is to reduce the range of the
   signals seen by the sensitive stages in the receiver. The AGC stage is
   designed to vary its gain depending on the input signal; stronger signals
   get less gain, and this has the effect of compressing the amplitude range.
   This is the desired response."

I believe this paragraph and the accompanying graphic can be misleading to the 
unwary.  AGC does not compress the range of signals, it simply lowers the gain 
through the receiver.  The range (difference between) signals might well be 130 
dB at the input but it better be 130 dB everywhere else in the receiver too. If 
lower level signals are driven into the internal noise level because of gain 
reduction, so be it; that should be the only reduction in range.


Al continues:

   "But signals above this threshold will be acted on by the AGC. Even though
   in real life an S9 signal is 5 S-units stronger than an S4 signal, because
   of the AGC it will sound only 11.1 dB louder – less than 2 S-units louder.
   This is because, reading from the above graph, an S4 (-103 dBm) signal
   produces -15.3 dBV of audio output and an S9 (-73 dBm) signal produces -4.2
   dBV, a difference of 11.1 dB. A five S-unit difference has been reduced to a
   less-than-two S-unit difference."

Some are going to read this and mistakenly believe that while receiving both an 
S9 signal and an S4 signal, AGC is going to reduce the ratio between them from 5 
S-units to two S-units.


Hence, I suspect that "mush" the proponents believe that AGC somehow magically 
reduces the amplitude of the stronger signal that activates the AGC but allows 
the weaker ones to have full gain, so that they "catch up" and become 
indistinguishable from the stronger one.  That's a limiting receiver, nice for 
FM, not so nice for CW/SSB.


All IMHO, of course,

Wes  N7WS



 On 3/5/2017 10:50 PM, Al Lorona wrote:

I spent a little bit of time this weekend and put together yet another K3 AGC (YAKA) 
"white paper" to put some measurements and discussion of the results down in 
the hope that others may benefit. Maybe it'll help folks understand AGC better by 
demystifying some of the K3 idiosyncrasies. I hope it makes you think about a few things 
in a way that maybe never occurred to you. I put the document in my Dropbox at the 
following link:
  


https://www.dropbox.com/s/drfujqupr4pcet3/Getting%20the%20Most%20Out%20of%20K3%20AGC%20System.pdf?dl=0


I'll leave the file there for several days in case any of y'all are interested.

73,

Al  W6LX
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Re: [Elecraft] [K3] AGC White Paper

[Al Lorona]

Yup, I knew that would cause confusion. That's NOT what I meant. I meant that 
if you listen to ONE signal at a time, their apparent amplitudes do not reflect 
reality, because of the AGC. If BOTH signals are present in the passband at the 
same time, then my comments DO NOT apply. I was ONLY talking about hearing ONE 
signal AT A TIME.

NONE of my discussion EVER presupposed more than ONE signal being received at a 
time.

THANK YOU. :^)


I am beginning to believe that it's impossible to shed any more light on this 
topic. It continues to be one of the most misunderstood areas of all, and I'm 
not sure if any effort can clear up the confusion without adding more confusion 
of its own. At least, I know I've failed! The next time someone asks a question 
about AGC, I'm going to chomp down on a towel, duct tape my arms to the chair, 
and start my breathing exercises: deep breath hold. exhale. 
again.


Al  W6LX







From: Wes Stewart 
To: elecraft@mailman.qth.net 
Sent: Monday, March 6, 2017 10:19 AM
Subject: Re: [Elecraft] [K3] AGC White Paper


In Al's very nicely done paper he has this paragraph:

"The purpose of Automatic Gain Control (AGC) is to reduce the range of the
signals seen by the sensitive stages in the receiver. The AGC stage is
designed to vary its gain depending on the input signal; stronger signals
get less gain, and this has the effect of compressing the amplitude range.
This is the desired response."

I believe this paragraph and the accompanying graphic can be misleading to the 
unwary.  AGC does not compress the range of signals, it simply lowers the gain 
through the receiver.  The range (difference between) signals might well be 130 
dB at the input but it better be 130 dB everywhere else in the receiver too. If 
lower level signals are driven into the internal noise level because of gain 
reduction, so be it; that should be the only reduction in range.

Al continues:

"But signals above this threshold will be acted on by the AGC. Even though
in real life an S9 signal is 5 S-units stronger than an S4 signal, because
of the AGC it will sound only 11.1 dB louder – less than 2 S-units louder.
This is because, reading from the above graph, an S4 (-103 dBm) signal
produces -15.3 dBV of audio output and an S9 (-73 dBm) signal produces -4.2
dBV, a difference of 11.1 dB. A five S-unit difference has been reduced to a
less-than-two S-unit difference."

Some are going to read this and mistakenly believe that while receiving both an 
S9 signal and an S4 signal, AGC is going to reduce the ratio between them from 
5 
S-units to two S-units.

Hence, I suspect that "mush" the proponents believe that AGC somehow magically 
reduces the amplitude of the stronger signal that activates the AGC but allows 
the weaker ones to have full gain, so that they "catch up" and become 
indistinguishable from the stronger one.  That's a limiting receiver, nice for 
FM, not so nice for CW/SSB.

All IMHO, of course,

Wes  N7WS




  On 3/5/2017 10:50 PM, Al Lorona wrote:
> I spent a little bit of time this weekend and put together yet another K3 AGC 
> (YAKA) "white paper" to put some measurements and discussion of the results 
> down in the hope that others may benefit. Maybe it'll help folks understand 
> AGC better by demystifying some of the K3 idiosyncrasies. I hope it makes you 
> think about a few things in a way that maybe never occurred to you. I put the 
> document in my Dropbox at the following link:
>  
>
> https://www.dropbox.com/s/drfujqupr4pcet3/Getting%20the%20Most%20Out%20of%20K3%20AGC%20System.pdf?dl=0
>
>
> I'll leave the file there for several days in case any of y'all are 
> interested.
>
> 73,
>
> Al  W6LX
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> Elecraft mailing list
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>

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Re: [Elecraft] [K3] AGC White Paper

[Don Wilhelm]

Wes is correct.  Let me say it in a slightly different way.
The AGC simply reduces the gain of the receiver - and it will respond 
mainly to the strongest signal in the passband.  Actually it responds to 
the integral of all the signals in the passband, but if there is a 
single stronger one it will predominate.


When the receiver gain is reduced, ALL the signals will be 
proportionally reduced in amplitude - including the weaker ones.  This 
is often referred to as "AGC Pumping".


73,
Don W3FPR



On 3/6/2017 1:19 PM, Wes Stewart wrote:

In Al's very nicely done paper he has this paragraph:

   "The purpose of Automatic Gain Control (AGC) is to reduce the range
of the
   signals seen by the sensitive stages in the receiver. The AGC stage is
   designed to vary its gain depending on the input signal; stronger
signals
   get less gain, and this has the effect of compressing the amplitude
range.
   This is the desired response."

I believe this paragraph and the accompanying graphic can be misleading
to the unwary.  AGC does not compress the range of signals, it simply
lowers the gain through the receiver.  The range (difference between)
signals might well be 130 dB at the input but it better be 130 dB
everywhere else in the receiver too. If lower level signals are driven
into the internal noise level because of gain reduction, so be it; that
should be the only reduction in range.

Al continues:

   "But signals above this threshold will be acted on by the AGC. Even
though
   in real life an S9 signal is 5 S-units stronger than an S4 signal,
because
   of the AGC it will sound only 11.1 dB louder – less than 2 S-units
louder.
   This is because, reading from the above graph, an S4 (-103 dBm) signal
   produces -15.3 dBV of audio output and an S9 (-73 dBm) signal
produces -4.2
   dBV, a difference of 11.1 dB. A five S-unit difference has been
reduced to a
   less-than-two S-unit difference."

Some are going to read this and mistakenly believe that while receiving
both an S9 signal and an S4 signal, AGC is going to reduce the ratio
between them from 5 S-units to two S-units.


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Re: [Elecraft] [K3} AGC White Paper

[Igor Sokolov]

Eric,
Thank you. This is really a great idea wich is if ever implemented would 
make me finally purchase P3.

I am sure Elecraft is listening.

73, Igor UA9CDC

06.03.2017 12:29, Erik Basilier пишет:

Al, your paper looks very helpful for the situation when the concepts need
to be studied. After one has a reasonable understanding of the concepts, the
stituation that comes up now and then is wanting to change some of the AGC
parameters in the K3. I don't know about others, but I tend to forget the
direction of parameters such as AGC "slope". Do I want to increase or
decrease the number to achieve my intended result? That is not about
understanding the concepts, but simply about an arbitrary definition that
can be equally "right" whether it is one way or the other. There are many
other examples of K3 parameters that have names that don't fully describe
what they do. Of course, the parameter names must be (too) short because of
the display limitations. However, when one has a P3, that opens up a whole
different world in terms of graphic displays. It seems to me that something
like an AGC curve could be displayed graphically (as in your paper) right
when the parameter is being changed. That way one would not have to worry
about a detailed definition; just turn the knob and see the effect. The
graph would be made extra helpful by the fact that the actual noise level is
visible at the same time. No doubt other K3 parameters could become more
user-friendly if treated in a similar way.

  


73,

Erik K7TV

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Re: [Elecraft] [K3] AGC White Paper

[Jim Brown]

On Mon,3/6/2017 11:29 AM, Don Wilhelm wrote:
This is often referred to as "AGC Pumping". 


Yes, BUT -- there is distortion associated with AGC action, and that 
distortion is what is perceived as "mush."


[Remember that the fundamental definition of distortion is "anything in 
the output that's not the input multiplied by a constant. Distortion can 
include time-variable gain, non-constant amplitude and phase response as 
a function of time or frequency, and amplitude non-linearity, variable 
time response. ALL of these distortions have the potential for confusing 
the ear-brain when trying to get intelligence from a signal, or 
providing aural satisfaction when listening to music. The K2 provides a 
great example. It sounds great and audio is easy to copy when listening 
to a SSB signal through the TX filter, but sounds awful and makes copy 
very difficult when the crystal filters are stagger tuned to provide 
narrower bandwidth. That's because the frequency response is pretty flat 
for the TX filter, but looks like a side view of the Rocky Mountains 
with the stagger tuned filters, and because every change in amplitude 
response is accompanied by non-constant phase response.]


More important -- this "mush" problem is NOT a theoretical concept -- 
the problem has been experienced by hundreds of great CW operators in 
contests and DX pileups. Those operators have, by careful experimenting 
based on their understanding of how AGC works, and by listening to the 
results of tweaking AGC parameters, developed settings that SOLVE THE 
PROBLEM. Caps added for emphasis. In general, their solutions are quite 
similar, differing only in degree.


This is NOT a problem for casual contesters or DXers, who either don't 
call CQ in contests or don't have a big enough station or a callsign 
that's rare enough in a given contest to generate a pileup. Most of the 
time I'm operating I fall into the first category, but occasionally the 
second. I've tried the recommendations of several top CW contesters, and 
I do agree that the result is making multiple callers easier for my 
brain to separate.


73, Jim K9YC


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Re: [Elecraft] [K3} AGC White Paper

[Jim Brown]

On Mon,3/6/2017 11:42 AM, Igor Sokolov wrote:
This is really a great idea wich is if ever implemented would make me 
finally purchase P3. 



Igor,

While it's a nice idea, it may or may not be possible to implement. BUT 
-- we're both pretty active contesters, and I wouldn't dream of working 
a contest without one. The SVGA card makes it even more useful -- the 
waterfall can be set to provide 2 minutes on screen, which really helps 
when trying to find a run frequency. You can look at the patterns to see 
which frequencies have someone running, and even when skip doesn't let 
you see the run station, you often see his callers. A waterfall tweaked 
for lots of averaging is great for finding weak signals on a band that 
is barely open. And a P3 is great for chasing down sources of RX noise.


73, Jim K9YC


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Re: [Elecraft] [K3} AGC White Paper

[Fred Jensen]

I think about it as follows:

THR: The signal level at which AGC action begins.  Lower number = lower 
signal level where AGC begins.


SLP: Wayne is an EE and I'll bet he views SLP as the degree of gain 
compression in the AGC system.  Thus, higher SLP values mean a higher 
amount of "compression" [and more flat] curve after threshold.


I'm a math dude, not an EE, and I view "slope" as the first derivative 
of the AGC gain function ... which is unfortunately exactly backwards to 
the way it really works.  I get around this by assuming "SLP" is a 
really weird acronym for COMPRESSION and not for SLOPE.


Maybe that will help you.

73,

Fred K6DGW
Sparks NV
Washoe County DM09dn

On 3/5/2017 11:29 PM, Erik Basilier wrote:

I don't know about others, but I tend to forget the
direction of parameters such as AGC "slope". Do I want to increase or
decrease the number to achieve my intended result?


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Re: [Elecraft] [K3] AGC White Paper

[brian]

For curiosity we looked at the lower end of the curve with SpectrumLab 
having a 0.27 Hz effective noise bandwidth at audio.


The K3 (not S here) shows AF linearity to more than 40 dB below S1!

So you guys with a low noise floor and ultra narrow digital modes could 
potentially do wonders.


73 de Brian/K3KO

On 3/6/2017 15:11 PM, Cady, Fred wrote:

Very nice Al  Thanks.

73,

Fred KE7X




From: Elecraft  on behalf of Al Lorona 

Sent: Sunday, March 5, 2017 10:50 PM
To: Elecraft Reflector
Subject: [Elecraft] [K3] AGC White Paper

I spent a little bit of time this weekend and put together yet another K3 AGC (YAKA) 
"white paper" to put some measurements and discussion of the results down in 
the hope that others may benefit. Maybe it'll help folks understand AGC better by 
demystifying some of the K3 idiosyncrasies. I hope it makes you think about a few things 
in a way that maybe never occurred to you. I put the document in my Dropbox at the 
following link:


https://www.dropbox.com/s/drfujqupr4pcet3/Getting%20the%20Most%20Out%20of%20K3%20AGC%20System.pdf?dl=0


I'll leave the file there for several days in case any of y'all are interested.

73,

Al  W6LX
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Re: [Elecraft] [K3] AGC White Paper

[Joe Subich, W4TV]

On 3/6/2017 2:29 PM, Don Wilhelm wrote:

Actually it responds to the integral of all the signals in the
passband, but if there is a single stronger one it will predominate.


In truth, depending on the AGC *attack time constant* the AGC system
responds to the *instantaneous peak voltage* of all signals in the
passband.  Even for two signals where one signal is *only* 10 dB
stronger than the other, the *instantaneous peak voltage* can be as
much as 20 dB greater than the stronger signal alone.

With multiple signals, e.g. a large pile-up, and [relatively] slow
attack times, the instantaneous peak voltage can drive the ADC into
clipping before the AGC can react while with very fast attack and
decay times AGC can "pump" the receiver gain at a syllabic rate and
further "muddy" the recovered audio.

Steady state (single signal, single tone) measurements can show the
general AGC behavior but it is still an "art" to find the best
combination of attack time, decay time, threshold, slope (gain
reduction) above the threshold, "hold" times and *overall gain*
to keep peak signal voltages below the ADC clipping point and
simultaneously keeping the AGC response from "pumping" receiver
gain in such a way as to generate IMD (mush).

The key here is the *DYNAMIC* response of the AGC system.

73,

   ... Joe, W4TV


On 3/6/2017 2:29 PM, Don Wilhelm wrote:

Wes is correct.  Let me say it in a slightly different way.
The AGC simply reduces the gain of the receiver - and it will respond
mainly to the strongest signal in the passband.  Actually it responds to
the integral of all the signals in the passband, but if there is a
single stronger one it will predominate.

When the receiver gain is reduced, ALL the signals will be
proportionally reduced in amplitude - including the weaker ones.  This
is often referred to as "AGC Pumping".

73,
Don W3FPR



On 3/6/2017 1:19 PM, Wes Stewart wrote:

In Al's very nicely done paper he has this paragraph:

   "The purpose of Automatic Gain Control (AGC) is to reduce the range
of the
   signals seen by the sensitive stages in the receiver. The AGC stage is
   designed to vary its gain depending on the input signal; stronger
signals
   get less gain, and this has the effect of compressing the amplitude
range.
   This is the desired response."

I believe this paragraph and the accompanying graphic can be misleading
to the unwary.  AGC does not compress the range of signals, it simply
lowers the gain through the receiver.  The range (difference between)
signals might well be 130 dB at the input but it better be 130 dB
everywhere else in the receiver too. If lower level signals are driven
into the internal noise level because of gain reduction, so be it; that
should be the only reduction in range.

Al continues:

   "But signals above this threshold will be acted on by the AGC. Even
though
   in real life an S9 signal is 5 S-units stronger than an S4 signal,
because
   of the AGC it will sound only 11.1 dB louder – less than 2 S-units
louder.
   This is because, reading from the above graph, an S4 (-103 dBm) signal
   produces -15.3 dBV of audio output and an S9 (-73 dBm) signal
produces -4.2
   dBV, a difference of 11.1 dB. A five S-unit difference has been
reduced to a
   less-than-two S-unit difference."

Some are going to read this and mistakenly believe that while receiving
both an S9 signal and an S4 signal, AGC is going to reduce the ratio
between them from 5 S-units to two S-units.


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