K3 AGC Mod Test This Weekend

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K3 AGC Mod Test This Weekend

Dennis Egan
This weekend I will be participating in the Stew Perry 160M contest, as
will many of you.
For the contest, I've arranged to do some testing of the IMD Mod as put
forth by N6KR in
a recent email.  I will have two K3s available, one with the IMD mod
(2uf in parallel with the
.1uf already on the pcb) and one without the mod.  The audio from each
will be run to
a sound card and one radio will be on the left channel, and the other
radio on the right channel,
so it will be easy to compare the two audio streams.

K3s will be setup as follows:
Same MCU and DSP firmware
AGC parameters:
DCY  Soft
HLD   .30
PLS   Nor
SLP   000
THR   008
F       120
S       020
AGC as selected using front panel push button will be "slow".
All RxEq will be flat, ie. 0
Preamp Off
Att- haven't decided on this yet, but both radios will be the same.
Crystal Filter- 400Hz
Bandwidth setting- 400Hz
Headphone audio from an SO2R Box will be routed to the sound card for
recording.
     The program I use to record the audio will give me 1-hour wav files.
RF gain adjusted to same number on both radios via N1MM Cat command
Main Antenna will go through K3(1) Ant 1 jack
K3(1) Ant Out will go to K3(2) Ant 1 Jack
K3(2) will have power reduced to zero and in TEST mode
K3(2) will also be put into transmit mode, but not keyed, when K3(1) is
transmitting
     by using N1MM Cat commands {CAT2ASC TX;} CQ SP W1UE W1UE {CAT2ASC RX;}

By putting K3(2) into Tx mode when keying K3(1), I'm figuring the front
ends on both radios
will not be damaged.  The antenna in use will be a 160M 4-square, so I'm
confident there
will be plenty of signal for both rigs.  If there is a better way to do
this, I'm listening.

So that I don't have to listen to 14 hours of audio to find some "mush",
I will also be
keeping a log of the times when I do hear it.  I'm particularly
interested to see if I can
actually hear the difference in audio from this reduction in IMD.

Comments as to my setup, and suggestions on other things that I may want
to standardize,
are appreciated.

Dennis W1UE







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Re: K3 AGC Mod Test This Weekend

Leigh L. Klotz Jr WA5ZNU
Administrator
Here's a link to the message from Wayne N6KR that Dennis W1UE is referring to.  It's buried in a thread about contest scores.

http://elecraft.365791.n2.nabble.com/Fw-CQ-WW-DX-Contest-CW-2011-Unofficial-claimed-scores-tp7060148p7061538.html
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Re: K3 AGC Mod Test This Weekend

Arie Kleingeld PA3A-2
In reply to this post by Dennis Egan
Dennis,

Thanks for this try-out! I'm looking forward to hear the results.

Some suggestions:
- 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.
- maybe set the SLP to 8 or higher. This will make the AGC more active
in your test
- set AGC to F

73,
Arie PA3A


Op 14-12-2011 22:53, Dennis schreef:

> AGC parameters:
> DCY  Soft
> HLD   .30
> PLS   Nor
> SLP   000
> THR   008
> F       120
> S       020
> AGC as selected using front panel push button will be "slow".
> All RxEq will be flat, ie. 0
> Preamp Off
> Att- haven't decided on this yet, but both radios will be the same.
> Crystal Filter- 400Hz
> Bandwidth setting- 400Hz
>
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Re: K3 AGC Mod Test This Weekend

Cady, Fred
Slope >0 flattens the agc response. Have a look at some curves on The AGC Story on ke7x.com


-----Original Message-----
From: [hidden email] on behalf of Arie Kleingeld PA3A
Sent: Thu 12/15/2011 3:08 AM
To: [hidden email]
Subject: Re: [Elecraft] K3 AGC Mod Test This Weekend
 
Dennis,

Thanks for this try-out! I'm looking forward to hear the results.

Some suggestions:
- 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.
- maybe set the SLP to 8 or higher. This will make the AGC more active
in your test
- set AGC to F

73,
Arie PA3A


Op 14-12-2011 22:53, Dennis schreef:

> AGC parameters:
> DCY  Soft
> HLD   .30
> PLS   Nor
> SLP   000
> THR   008
> F       120
> S       020
> AGC as selected using front panel push button will be "slow".
> All RxEq will be flat, ie. 0
> Preamp Off
> Att- haven't decided on this yet, but both radios will be the same.
> Crystal Filter- 400Hz
> Bandwidth setting- 400Hz
>
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Re: K3 AGC Mod Test This Weekend

Bill W4ZV
In reply to this post by Dennis Egan
Dennis I'd consider the following minor tweaks to your AGC settings:

HLD 0.20
AGS-S 040

Most importantly, set your RF Gain back so that the S-meters rest above the residual noise floor (including clicks, phase noise, etc).  Once RF Gain is set, then adjust AF Gain to suit your ears/headphones.  I would definitely try to find some pileups before the contest to confirm your AGC settings are not too slow for reasonable recovery in fast-paced exchanges.  I would also not be using QSK.  Of course you can try changing any of your settings during the contest to eliminate/induce mush.

73 & GL!

Bill  W4ZV
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Re: K3 AGC Mod Test This Weekend

Arie Kleingeld PA3A-2
In reply to this post by Cady, Fred
Fred,
Maybe I did not express it right:
I want some more activity from the AGC means for me:  audio response
more flat with different signal levels. SLP 15 is most flat audio level
in this case.

73,
Arie PA3A


Op 15-12-2011 15:17, Cady, Fred schreef:

>
> Slope >0 flattens the agc response. Have a look at some curves on The
> AGC Story on ke7x.com
>
>
> -----Original Message-----
>
>
>
> Some suggestions:
> - 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.
> - maybe set the SLP to 8 or higher. This will make the AGC more active
> in your test
> - set AGC to F
>
> 73,
> Arie PA3A
>
>
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Re: K3 AGC Mod Test This Weekend

Dave Hachadorian
In reply to this post by Dennis Egan
Here are what I consider to be the best contest CW settings for
the K3:

config AF GAIN = HIGH (to increase overall post-AGC gain)
config AGC DCY = SOFT
config AGC HLD = 0.20
config AGC PLS = NOR
config AGC SLP = 000 (steepest)
config AGC THR = 008 (highest)
config AGC - F = 200 (fastest)
config AGC - S = 020
Front panel select AGC FAST
Front panel AF GAIN as loud as your ears can stand, 3 o'clock for
   me.
Attenuator definitely ON, and preamp OFF for 160 (unless using
   separate RX antenna).
Front Panel RF Gain set to show 1 or 2 S-units of band noise
   meter wiggle (about 1 o'clock for me)

I know that selecting AGC SLOW on the front panel is supposed to
reduce IMD, but for me, the mushiness is due to the
aggressiveness of the K3's AGC curve, not IMD.  Slow AGC
also introduces desensing due to static crashes and other loud
transients, so is undesirable for that reason.

My next experiment will be to have an N1MM logging program
macro available to send RF Gain command RG090 if a loud
pileup shows up.  RF Gain will be returned to 200 by appending
the RG200 command to the "thank you" message.  This should
be the ultimate in "riding the RF gain control."


Dave Hachadorian, K6LL
Yuma, AZ





-----Original Message-----
From: Dennis
Sent: Wednesday, December 14, 2011 2:53 PM
To: [hidden email]
Subject: [Elecraft] K3 AGC Mod Test This Weekend

This weekend I will be participating in the Stew Perry 160M
contest, as
will many of you.
For the contest, I've arranged to do some testing of the IMD Mod
as put
forth by N6KR in
a recent email.  I will have two K3s available, one with the IMD
mod
(2uf in parallel with the
.1uf already on the pcb) and one without the mod.  The audio from
each
will be run to
a sound card and one radio will be on the left channel, and the
other
radio on the right channel,
so it will be easy to compare the two audio streams.

K3s will be setup as follows:
Same MCU and DSP firmware
AGC parameters:
DCY  Soft
HLD   .30
PLS   Nor
SLP   000
THR   008
F       120
S       020
AGC as selected using front panel push button will be "slow".
All RxEq will be flat, ie. 0
Preamp Off
Att- haven't decided on this yet, but both radios will be the
same.
Crystal Filter- 400Hz
Bandwidth setting- 400Hz
Headphone audio from an SO2R Box will be routed to the sound card
for
recording.
     The program I use to record the audio will give me 1-hour
wav files.
RF gain adjusted to same number on both radios via N1MM Cat
command
Main Antenna will go through K3(1) Ant 1 jack
K3(1) Ant Out will go to K3(2) Ant 1 Jack
K3(2) will have power reduced to zero and in TEST mode
K3(2) will also be put into transmit mode, but not keyed, when
K3(1) is
transmitting
     by using N1MM Cat commands {CAT2ASC TX;} CQ SP W1UE W1UE
{CAT2ASC RX;}

By putting K3(2) into Tx mode when keying K3(1), I'm figuring the
front
ends on both radios
will not be damaged.  The antenna in use will be a 160M 4-square,
so I'm
confident there
will be plenty of signal for both rigs.  If there is a better way
to do
this, I'm listening.

So that I don't have to listen to 14 hours of audio to find some
"mush",
I will also be
keeping a log of the times when I do hear it.  I'm particularly
interested to see if I can
actually hear the difference in audio from this reduction in IMD.

Comments as to my setup, and suggestions on other things that I
may want
to standardize,
are appreciated.

Dennis W1UE







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Help: http://mailman.qth.net/mmfaq.htm
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Please help support this email list:
http://www.qsl.net/donate.html 

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Re: K3 AGC Mod Test This Weekend

Lu Romero - W4LT
In reply to this post by Dennis Egan
Dave:

>My next experiment will be to have an N1MM logging program
>macro available to send RF Gain command RG090 if a loud
>pileup shows up.  RF Gain will be returned to 200 by
appending
>the RG200 command to the "thank you" message.  This should
>be the ultimate in "riding the RF gain control."

*EXCELLENT* idea!  Thanks for the tip!

-lu-

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