AGC settings with Firmware 3.03

[Dennis Egan]

I'm planning on a major effort in the RDXC this weekend, so I just
downloaded the beta firmware
3.03 and installed it in my K3.  After installing, my AGC parameters are
as follows:
AGC Dcy            Soft
AGC Hold           .30
AGC PLS            Norm
AGC SLP            000
AGC THR           008
AGC -F               120
AGC -S               020

Since I haven't used this before (and am a confirmed AGC OFF user on
CW), what kind
of parameters will give me the best performance in a pileup with 10
stations calling?

I've gotten used to AGC OFF, but there is a LOT of RF gain tweaking and
occasional
BLASTING out of the headphones when a strong signal follows a weak one.  
Using the
AF LIM of even 030 creates too much  distortion on even fairly weak signals.

I should have time in this contest to play with the AGC settings, so I'm
open to any suggested
settings that anyone has.

Dennis W1UE
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[David Gilbert]

For the most part, and as Wayne has said several times, ANY non-linear
gain characteristic is going to create some distortion of a signal, and
it will create additional passband mixer products if multiple signals
exist.  Those distortion and mixer products will blur whatever you're
trying to copy.  Keep in mind that narrow filters help reduce the
candidates for mixing, and that noise spikes count as "signals".

AGC is by definition non-linear gain, but so is the AF LIM audio
limiter, and in my opinion the trick for working pileups is to use just
enough AGC (or use none at all and ride the RF GAIN control) to keep the
audio from reaching the AF LIM threshold.  K6LL and others have pointed
out that the max limit of 30 for that setting should probably be raised,
but I've been able to find acceptable AGC settings that seem to keep my
head from banging up against that ceiling.  A very good reference for me
was the set of curves generated by K8ZOA, and by looking at them you can
see the extreme non-linearity that exists for aggressive AGC settings
... especially around the threshold breakpoint.  Using low values of AGC
THR appear to me to be a very bad idea for any kind of weak signal
contest work.

http://www.cliftonlaboratories.com/Documents/Elecraft%20K3%20Transceiver%20AGC%20Parameters%20and%20S-meter.pdf

The only thing more non-linear than a non-linear gain characteristic is
a time varying non-linear gain characteristic that changes rapidly
enough to occur during the signal(s) you're trying to copy.  In a
contest you generally want to have quick AGC recovery for snappy QSOs,
but fast AGC with aggressive threshold and slope settings is probably
the worst of all possibilities, especially in the presence of noise
spikes.  It just whipsaws the gain curve around all over the place.

The K3 has a wide enough range of available AGC settings to do the job
you need to do ... or ... to make a mess out of your receiver, depending
upon the conditions.  I really like the addition of the AGC DCY = SOFT
feature, but I do not like the default settings for AGC THR and AGC SLP.

There certainly is no ideal AGC setting anyway.  The best settings for
single signal copy in a low noise situation (like prowling for weak DX)
are certainly not going to be very good for working DX in a contest, and
the ideal settings for working a strong signal pileup on 20m when the
band is quiet probably won't work very well for distinguishing between
multiple weaker signals in the midst of 80m noise spikes.  Personally, I
think a neat feature for a piece of software like K3_EZ would be to
allow multiple combinations of AGC settings that could be stored and
recalled as needed for changing conditions instead of having to change
each parameter singly and separately.  Just click on a box (say one of
five or six?) and send the appropriate full set of AGC settings to the
K3 on the fly.

All that being said, my AGC settings are almost identical to yours
except that I have AGC PLS = OFF.  My K3 is only about 6 weeks old,
though, and I haven't had a chance to use it in very many contests, so
I'm still experimenting a LOT with the settings myself.

73,
Dave   AB7E


W1UE wrote:

> I'm planning on a major effort in the RDXC this weekend, so I just
> downloaded the beta firmware
> 3.03 and installed it in my K3.  After installing, my AGC parameters are
> as follows:
> AGC Dcy            Soft
> AGC Hold           .30
> AGC PLS            Norm
> AGC SLP            000
> AGC THR           008
> AGC -F               120
> AGC -S               020
>
> Since I haven't used this before (and am a confirmed AGC OFF user on
> CW), what kind
> of parameters will give me the best performance in a pileup with 10
> stations calling?
>
> I've gotten used to AGC OFF, but there is a LOT of RF gain tweaking and
> occasional
> BLASTING out of the headphones when a strong signal follows a weak one.  
> Using the
> AF LIM of even 030 creates too much  distortion on even fairly weak signals.
>
> I should have time in this contest to play with the AGC settings, so I'm
> open to any suggested
> settings that anyone has.
>
> Dennis W1UE

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[Joe Planisky]

Couldn't you do this already with the K3Utility's save and restore  
configuration feature?

73
--
Joe KB8AP

On Mar 18, 2009, at 10:04 AM, David Gilbert wrote:

> Personally, I
> think a neat feature for a piece of software like K3_EZ would be to
> allow multiple combinations of AGC settings that could be stored and
> recalled as needed for changing conditions instead of having to change
> each parameter singly and separately.  Just click on a box (say one of
> five or six?) and send the appropriate full set of AGC settings to the
> K3 on the fly.
>

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[Dave Hachadorian]

----- Original Message -----
From: "W1UE" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, March 18, 2009 11:53 AM
Subject: [Elecraft] AGC settings with Firmware 3.03


> I've gotten used to AGC OFF, but there is a LOT of RF gain
> tweaking and
> occasional
> BLASTING out of the headphones when a strong signal
> follows a weak one.
> Using the
> AF LIM of even 030 creates too much  distortion on even
> fairly weak signals.
----------------------------
Hi Dennis,

Regarding AGC OFF -

If you plug your headphones into the speaker jack, you can
use AGC OFF and turn down the AF gain, and avoid hitting the
K3's limiter. I have a little network with a small amount of
attenuation to cut down on background hiss. I also have back
to back 1N5818 Schottky Diodes across the headphones for
hearing protection. The diodes introduce just a little fuzz
on the loudest signals - nothing like the gross distortion
caused by the K3's AF limiter.

Dave Hachadorian, K6LL
Yuma, AZ

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[David Gilbert]

I suppose, but that seems like an awfully slow route to be trying to use
during a contest, especially if you need to try a couple of different
ones to see which works best at the time (different bands, band open or
closing, running versus S&P for weak multipliers, etc).  I could change
the settings manually quicker, I think.

73,
Dave   AB7E



Joe Planisky wrote:

> Couldn't you do this already with the K3Utility's save and restore
> configuration feature?
>
> 73
> --
> Joe KB8AP
>
> On Mar 18, 2009, at 10:04 AM, David Gilbert wrote:
>
>> Personally, I
>> think a neat feature for a piece of software like K3_EZ would be to
>> allow multiple combinations of AGC settings that could be stored and
>> recalled as needed for changing conditions instead of having to change
>> each parameter singly and separately.  Just click on a box (say one of
>> five or six?) and send the appropriate full set of AGC settings to the
>> K3 on the fly.
>>
>
>

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[Dick Dievendorff]

The K3 Utility's save/restore is "all or nothing", and it takes a while to
perform. It's not a "click on a box" experience; it takes minutes and a full
MCU reset.

Different objectives.  Bill has done a fine job with K3-EZ.

http://home.roadrunner.com/~n2bc/SW.htm

Dick, K6KR


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Joe Planisky
Sent: Wednesday, March 18, 2009 10:57 AM
To: David Gilbert
Cc: [hidden email]
Subject: Re: [Elecraft] AGC settings with Firmware 3.03

Couldn't you do this already with the K3Utility's save and restore  
configuration feature?

73
--
Joe KB8AP

On Mar 18, 2009, at 10:04 AM, David Gilbert wrote:

> Personally, I
> think a neat feature for a piece of software like K3_EZ would be to
> allow multiple combinations of AGC settings that could be stored and
> recalled as needed for changing conditions instead of having to change
> each parameter singly and separately.  Just click on a box (say one of
> five or six?) and send the appropriate full set of AGC settings to the
> K3 on the fly.
>

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[Dave Hachadorian]

----- Original Message -----
From: "Dick Dievendorff" <[hidden email]>
To: "'Joe Planisky'" <[hidden email]>; "'David Gilbert'"
<[hidden email]>
Cc: <[hidden email]>
Sent: Wednesday, March 18, 2009 6:46 PM
Subject: Re: [Elecraft] AGC settings with Firmware 3.03

>  Bill has done a fine job with K3-EZ.
> http://home.roadrunner.com/~n2bc/SW.htm
----------------------------

Looks pretty cool! I wonder if K3-EZ can somehow share the
rs-232 link with a logging program?

Dave Hachadorian, K6LL
Yuma, AZ


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[Doug Faunt N6TQS [phone]]

I wonder if LP-BRIDGE would work for this?

73, doug

   From: "Dave Hachadorian" <[hidden email]>
   Date: Wed, 18 Mar 2009 19:21:49 -0000


   ----- Original Message -----
   From: "Dick Dievendorff" <[hidden email]>
   To: "'Joe Planisky'" <[hidden email]>; "'David Gilbert'"
   <[hidden email]>
   Cc: <[hidden email]>
   Sent: Wednesday, March 18, 2009 6:46 PM
   Subject: Re: [Elecraft] AGC settings with Firmware 3.03

   >  Bill has done a fine job with K3-EZ.
   > http://home.roadrunner.com/~n2bc/SW.htm
   ----------------------------

   Looks pretty cool! I wonder if K3-EZ can somehow share the
   rs-232 link with a logging program?

   Dave Hachadorian, K6LL
   Yuma, AZ


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[KK6T]

I don't think K3-EZ works with LP-Bridge.

73 de Terry KK6T


Doug Faunt N6TQS [phone] wrote:

> I wonder if LP-BRIDGE would work for this?
>
> 73, doug
>
>    From: "Dave Hachadorian" <[hidden email]>
>    Date: Wed, 18 Mar 2009 19:21:49 -0000
>
>
>    ----- Original Message -----
>    From: "Dick Dievendorff" <[hidden email]>
>    To: "'Joe Planisky'" <[hidden email]>; "'David Gilbert'"
>    <[hidden email]>
>    Cc: <[hidden email]>
>    Sent: Wednesday, March 18, 2009 6:46 PM
>    Subject: Re: [Elecraft] AGC settings with Firmware 3.03
>
>    >  Bill has done a fine job with K3-EZ.
>    > http://home.roadrunner.com/~n2bc/SW.htm
>    ----------------------------
>
>    Looks pretty cool! I wonder if K3-EZ can somehow share the
>    rs-232 link with a logging program?
>
>    Dave Hachadorian, K6LL
>    Yuma, AZ
>
>
> ______________________________________________________________
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>
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>
>
>  

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