AGC Information Please - Curious

I posted this question a week ago or so and did not hear a peep about it.  Two fellow list serve participants emailed me asking if I had gotten a response.  So, there is a small amount of interest.  Here is what I asked....

In an attempt to learn more about the K3 and understand AGC action...could somebody in the know explain in more detail what the following are doing.

AGC HLD (Hold?)
AGC PLS (Pulse?)
AGC SLP (Slope?)
AGC THR (Threshold?}
AGC-F (Fast)
AGC-S (Slow)

Please use non engineering terms....

Thank you....

Lee - K0WA




In our day and age it seems that Common Sense is in short supply.  If you don't have any Common Sense - get some Common Sense and use it.  If you can't find any Common Sense, ask for help from somebody who has some Common Sense.  Is Common Sense divine?
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[KK7P]

You can tap DISP when any of these are displayed and a short help
message will scroll across the VFO B display.

> AGC HLD (Hold?)

In slow AGC, this is the time that the AGC will hold its most recent
peak value before starting to decay.

> AGC PLS (Pulse?)

This defines the width of a signal that is considered a pulse (like
ignition noise) instead of data (like a CW dit).  If a pulse is
detected, the AGC rapidly decays back to its previous value after the
pulse ends.  Otherwise, the AGC assumes it was a signal and responds
accordingly.

> AGC SLP (Slope?)

This allows you to change the "flatness" of the AGC.  Some people like
ift flat (very strong signals and moderately weak signals all have the
same loudness).  Others prefer that stronger signals drive the audio
level alittle harder than weaker signals.

> AGC THR (Threshold?}

Determines the level below which signals do not drive the AGC.

> AGC-F (Fast)

Sets the decay rate of the AGC in Fast mode.

> AGC-S (Slow)

Sets the decay rate of the AGC (after the Hold time) in Slow mode.

> Please use non engineering terms....

The best way to understand what these do is to play with them, adjusting
one parameter and operating the radio until you are comfortable with
what that parameter does, then changing another, etc., until you know
what they all do.  Then adjust them to optimize the K3 for your personal
preferences.

73,

Lyle KK7P

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[Klaus Koppendorfer]

Hi Lyle !

i obseved, that the combination HLD (30ms) and PLS (on) not working well
I have dedected pulses every second at my qth - so hold let the agc hold
for 30ms and agc goes down... downsizing HLD to zero it works well,
so maybe you can also include that any hold will be disabled when PLS is
decaying back

73
oe6kyg

>
> You can tap DISP when any of these are displayed and a short help
> message will scroll across the VFO B display.
>
> > AGC HLD (Hold?)
>
> In slow AGC, this is the time that the AGC will hold its most recent
> peak value before starting to decay.
>
> > AGC PLS (Pulse?)
>
> This defines the width of a signal that is considered a pulse (like
> ignition noise) instead of data (like a CW dit).  If a pulse is
> detected, the AGC rapidly decays back to its previous value after the
> pulse ends.  Otherwise, the AGC assumes it was a signal and responds
> accordingly.
>
> > AGC SLP (Slope?)
>
> This allows you to change the "flatness" of the AGC.  Some people like
> ift flat (very strong signals and moderately weak signals all have the
> same loudness).  Others prefer that stronger signals drive the audio
> level alittle harder than weaker signals.
>
> > AGC THR (Threshold?}
>
> Determines the level below which signals do not drive the AGC.
>
> > AGC-F (Fast)
>
> Sets the decay rate of the AGC in Fast mode.
>
> > AGC-S (Slow)
>
> Sets the decay rate of the AGC (after the Hold time) in Slow mode.
>
> > Please use non engineering terms....
>
> The best way to understand what these do is to play with them, adjusting
> one parameter and operating the radio until you are comfortable with
> what that parameter does, then changing another, etc., until you know
> what they all do.  Then adjust them to optimize the K3 for your personal
> preferences.
>
> 73,
>
> Lyle KK7P
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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[Greg - AB7R]

Lee,

Do you mean more than what is in the manual?

AGC HLD [T] 000 (Advanced.) AGC “hold” time for voice modes. Specifies the number of
milliseconds that the SLOW AGC value is held after the signal drops below the
level that set the AGC. This is often helpful for SSB voice operation.

AGC PLS [T] NOR (Advanced.) NOR enables AGC noise pulse rejection.

AGC SLP [T] 10 (Advanced.) Higher values result in ‘flatter’ AGC (making signals at all
amplitudes closer in AF output level).

AGC THR [T] 5 (Advanced.) Sets AGC onset point; a higher number moves the onset up.

AGC-F [T] 120 (Advanced.) Sets fast AGC decay rate; a higher number means faster decay.

AGC-S [T] 20 (Advanced.) Sets slow AGC decay rate; a higher number means faster decay.

-------------------------
73,
Greg - AB7R
Whidbey Island WA
NA-065
K3#0009 and 0319

On Thu Mar 13  5:11 , Lee Buller  sent:

>
>I posted this question a week ago or so and did not hear a peep about it.  Two fellow
list serve participants emailed me asking if I had gotten a response.  So, there is a
small amount of interest.  Here is what I asked....
>
>In an attempt to learn more about the K3 and understand AGC action...could somebody
in the know explain in more detail what the following are doing.

>
>AGC HLD (Hold?)
>AGC PLS (Pulse?)
>AGC SLP (Slope?)
>AGC THR (Threshold?}
>AGC-F (Fast)
>AGC-S (Slow)
>
>Please use non engineering terms....
>
>Thank you....
>
>Lee - K0WA
>
>
>
>
>In our day and age it seems that Common Sense is in short supply.  If you don't have

any Common Sense - get some Common Sense and use it.  If you can't find any Common
Sense, ask for help from somebody who has some Common Sense.  Is Common Sense divine?
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com


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[w7aqk]

And I think if the boys at VP6DX had understood this, they
wouldn't have had any complaint about the AGC on the K3.

Dave W7AQK


----- Original Message -----
From: "Lyle Johnson" <[hidden email]>
To: "Elecraft Reflector" <[hidden email]>
Sent: Thursday, March 13, 2008 5:25 AM
Subject: Re: [Elecraft] AGC Information Please - Curious

> You can tap DISP when any of these are displayed and a
> short help message will scroll across the VFO B display.
>
>> AGC HLD (Hold?)
>
> In slow AGC, this is the time that the AGC will hold its
> most recent peak value before starting to decay.
>
>> AGC PLS (Pulse?)
>
> This defines the width of a signal that is considered a
> pulse (like ignition noise) instead of data (like a CW
> dit).  If a pulse is detected, the AGC rapidly decays back
> to its previous value after the pulse ends.  Otherwise,
> the AGC assumes it was a signal and responds accordingly.
>
>> AGC SLP (Slope?)
>
> This allows you to change the "flatness" of the AGC.  Some
> people like ift flat (very strong signals and moderately
> weak signals all have the same loudness).  Others prefer
> that stronger signals drive the audio level alittle harder
> than weaker signals.
>
>> AGC THR (Threshold?}
>
> Determines the level below which signals do not drive the
> AGC.
>
>> AGC-F (Fast)
>
> Sets the decay rate of the AGC in Fast mode.
>
>> AGC-S (Slow)
>
> Sets the decay rate of the AGC (after the Hold time) in
> Slow mode.
>
>> Please use non engineering terms....
>
> The best way to understand what these do is to play with
> them, adjusting one parameter and operating the radio
> until you are comfortable with what that parameter does,
> then changing another, etc., until you know what they all
> do.  Then adjust them to optimize the K3 for your personal
> preferences.
>
> 73,
>
> Lyle KK7P
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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Well, the manual is good, but it does not really define what the parameters are doing very well.  I think the Lyle did a good job of defining the parameters and letting  people in on what the engineer was doing, thinking, and planning.

I thought a broader and more detailed explanation would benefit me and others.

Lee - K0WA



In our day and age it seems that Common Sense is in short supply.  If you don't have any Common Sense - get some Common Sense and use it.  If you can't find any Common Sense, ask for help from somebody who has some Common Sense.  Is Common Sense divine?
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[Vic K2VCO]

Lyle Johnson wrote:

>> AGC SLP (Slope?)
>
> This allows you to change the "flatness" of the AGC.  Some people like
> ift flat (very strong signals and moderately weak signals all have the
> same loudness).  Others prefer that stronger signals drive the audio
> level alittle harder than weaker signals.
>
>> AGC THR (Threshold?}
>
> Determines the level below which signals do not drive the AGC.

These are the two that I have changed from the default.

I decreased the value of SLP so that there would be a greater perceived
difference between weak and strong signals.  I might increase it in a
contest to protect my ears and reduce knob twisting.

I reduced THR because I do not want *any* AGC action on the weakest signals.

Your preferences may definitely vary and Lyle's advice to try these
parameters to see what happens is good. You can always find out what the
default was by pressing DISP, so you don't need to worry about getting lost.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Barry N1EU]

Vic K2VCO wrote

I reduced THR because I do not want *any* AGC action on the weakest signals.

Shouldn't you be increasing THR if you don't want AGC action on weakest signals, i.e. raising the threshold for  the onset of AGC action and not amplifying the weakest signals through AGC action?

73,
Barry N1EU

[Vic K2VCO]

Barry N1EU wrote:

> Shouldn't you be increasing THR if you don't want AGC action on weakest
> signals, i.e. raising the threshold for  the onset of AGC action and not
> amplifying the weakest signals through AGC action?

I did whatever was necessary to raise the threshold...I vaguely
remembered that this meant reducing the numerical value of the
parameter, but I'm probably wrong.  What I did was make the AGC not come
on with the weakest signals.  If the manual says that this requires a
higher value for THR, then that's what I did!
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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