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Jan Erik Holm-2

Dec 04, 2011; 8:20pm

Re: K3 AGC Mush

28 posts

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
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

... [show rest of quote]

Jan Erik Holm-2

Dec 04, 2011; 8:22pm

Re: K3 AGC Mush

28 posts

In reply to this post by Eric Swartz - WA6HHQ

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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Guy, K2AV

Dec 04, 2011; 8:28pm

Re: K3 AGC Mush

1039 posts

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 <[hidden email]> 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.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

... [show rest of quote]

Eric Swartz - WA6HHQ

Dec 04, 2011; 8:31pm

Re: K3 AGC Mush

Administrator

2808 posts

In reply to this post by Jan Erik Holm-2

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
>>

... [show rest of quote]

alsopb

Dec 04, 2011; 8:34pm

Re: K3 AGC Mush

557 posts

In reply to this post by Jan Erik Holm-2

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:

... [show rest of quote]

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Jan Erik Holm-2

Dec 04, 2011; 8:55pm

Re: K3 AGC Mush

28 posts

In reply to this post by Eric Swartz - WA6HHQ

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
>>>
>

... [show rest of quote]

Merv Schweigert

Dec 04, 2011; 10:51pm

Re: K3 AGC Mush

201 posts

In reply to this post by Eric Swartz - WA6HHQ

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
>>>
>>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

... [show rest of quote]

Merv Schweigert

Dec 04, 2011; 11:11pm

Re: K3 AGC Mush

201 posts

In reply to this post by Eric Swartz - WA6HHQ

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
>>>
>>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

... [show rest of quote]

VE3GNO Daniel

Dec 04, 2011; 11:13pm

Fw: K3 AGC Mush

45 posts

In reply to this post by Eric Swartz - WA6HHQ

Hi Eric,

I remember few years ago we had a similar problem with digital AGC at work with a chipset and in order to reproduce the field problem I had to add a noise generator (via a channel emulator) on a top of multi-carrier generator to catch the bug, noise floor and noise characteristic was the bug trigger. Most likely sound like a software bug and this kind of bugs are hard to trace. Hopefully in a week or two I'll get my K3 and I'll try to play with it at work in my lab.

73

VE3GNO Daniel

From: Eric Swartz WA6HHQ - Elecraft <[hidden email]>
To: Jan Erik Holm <[hidden email]>
Cc: [hidden email]
Sent: Sunday, December 4, 2011 3:31:29 PM
Subject: Re: [Elecraft] K3 AGC Mush

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:

... [show rest of quote]

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Geoffrey Mackenzie-Kennedy-3

Dec 04, 2011; 11:57pm

Re: K3 AGC Mush

103 posts

In reply to this post by Merv Schweigert

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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dmb@lightstream.net

Dec 05, 2011; 12:25am

Re: K3 AGC Mush

184 posts

In reply to this post by Jan Erik Holm-2

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:

... [show rest of quote]

David Gilbert

Dec 05, 2011; 1:25am

Re: Fw: CQ WW DX Contest CW 2011 - Unofficial claimed scores

827 posts

In reply to this post by Grant Youngman

Of course Elecraft owes us an explanation. Thankfully Eric just
attempted to do exactly that, but why on earth would you think
otherwise?? The rig distorts signals in normal operation, and it is
definitely a problem for many competent contesters even if you don't
fall into that category. The list of top scoring contesters and serious
DXpeditioners who have stepped forward on this issue is getting pretty
large ... AND THEY ALL SAY THE SAME THING. And here's a bit of
enlightenment for you ... the guy who started this thread (KE7X) is the
guy who writes and sells the most comprehensive manual on the K3.

There are good reasons why simply turning off the AGC is not a good
solution when running a pileup, not the least of which is the
possibility to blow the output IC as some users have experienced when a
strong caller suddenly shows up. Besides, I don't recall anyone saying
that turning off the AGC was a definitive fix for the problem, and some
have openly said that it isn't. If it WAS a fix, I suspect that
Elecraft would be able to address the issue with software and I happen
to know that they have already said they haven't been able to.

As far as more clearly defining the problem is concerned, here's what is
probably needed:

a. At least five or six independent high purity signals within a narrow
frequency range. I typically use a 250 Hz 8-pole filter with DSP set to
300 Hz when contesting, but as Eric pointed out many callers are almost
zero beat with each other. The signals need to be such that sum and
difference products overlap with other signals within the same passband.

b. The signals need to be injected into the K3 front end with variable
attenuation and lots of isolation between them so that the test isn't
colored by the possibility of one signal source pulling the others.

c. The signals need to be keyed, preferably at different speeds from
each other. Constant tones won't cut it.

d. Assuming that the audio from the K3 was fed into a high quality
computer sound card, it probably would require some piece of software to
analyze the recorded wav file to quantify the relative level of the
undesired products relative to the pure tone inputs. I don't think
simply viewing on a spectrum analyzer would show anything because of the
timing dynamics of keying.

Now then, how many hams do you think have the necessary resources to
recreate those kinds of conditions?

At one point I considered using a program like CW Player to record
several different CW streams close in frequency, merge them, and then
feed them into the mic input of a second rig nearby driving a dummy
load. I didn't follow through on it because the was no way I could
quantify the possible mixing caused by the second rig before signals
ever got to the K3, but does that sound like someone who is simply too
lazy to turn off the AGC???

I'm glad to hear that Elecraft recognizes this as a problem and I am
anxiously looking forward to whatever they find.

For the record, my parameters that I use for CW are:

AGC DCY = SOFT
AGC HLD = 0.20
AGC PLS = NOR
AGC SLP = 000
AGC THR = 008
AGC-F = 140
AGC-S = 030

I mostly use AGC FAST for contests but change as needed. I never use NR
or NB at all ... ever.

Dave AB7E

On 12/4/2011 1:08 PM, Grant Youngman wrote:

> What I find most bothersome about these rants, is that somehow certain of the owner class seems to think that Elecraft OWES them a solution or an explanation. As though "mush" is enough of a description for a DSP wizard to have an epiphany and write a few lines of code and fix the problem, which is ill defined and probably difficult to reproduce in the lab.
>
> More telling is that it has been pointed out that turning off AGC eliminates the effects. I don't know about these guys, but turning off AGC when the issue is recognized -- since they can clearly recognize it -- sounds like a far more sane and reasonable solution than blaming their contest scores and apparent 'embarrassment' on 'mush' and trying to get some other radio vendor to fix whatever problem shows up in THAT radio.
>
> Isn't it reasonable to assume that a 'top contester' should know how to utilize his equipment beyond turning it on and twisting the dial? Geez.
>
> Grant/NQ5T
>
> Sent from my iPhone
>
> On Dec 4, 2011, at 1:44 PM, Mike Fatchett W0MU<[hidden email]> wrote:
>
>>
>> I am glad Elecraft is attempting to isolate this with more scientific
>> data instead of anecdotal comments. Did anyone bother to record any of
>> the mushiness they are describing? Use the line out and an audio
>> capture program. I would love to hear what you are hearing.
>>
>>

... [show rest of quote]

Merv Schweigert

Dec 05, 2011; 1:30am

Re: K3 AGC Mush

201 posts

In reply to this post by dmb@lightstream.net

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
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>>
>> ______________________________________________________________
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>>
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>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
> ______________________________________________________________
> Elecraft mailing list
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> Help: http://mailman.qth.net/mmfaq.htm
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>
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>

... [show rest of quote]

w0mu

Dec 05, 2011; 1:36am

Re: Fw: CQ WW DX Contest CW 2011 - Unofficial claimed scores

542 posts

In reply to this post by David Gilbert

It would be interesting to hear if a recording of this coming out of the
back of the K3 is the same as what is being heard at the headphone or
speaker jack. Obviously it should be.

Mike W0MU

W0MU-1 CC Cluster w0mu.net

On 12/4/2011 6:25 PM, David Gilbert wrote:

> Of course Elecraft owes us an explanation. Thankfully Eric just
> attempted to do exactly that, but why on earth would you think
> otherwise?? The rig distorts signals in normal operation, and it is
> definitely a problem for many competent contesters even if you don't
> fall into that category. The list of top scoring contesters and serious
> DXpeditioners who have stepped forward on this issue is getting pretty
> large ... AND THEY ALL SAY THE SAME THING. And here's a bit of
> enlightenment for you ... the guy who started this thread (KE7X) is the
> guy who writes and sells the most comprehensive manual on the K3.
>
> There are good reasons why simply turning off the AGC is not a good
> solution when running a pileup, not the least of which is the
> possibility to blow the output IC as some users have experienced when a
> strong caller suddenly shows up. Besides, I don't recall anyone saying
> that turning off the AGC was a definitive fix for the problem, and some
> have openly said that it isn't. If it WAS a fix, I suspect that
> Elecraft would be able to address the issue with software and I happen
> to know that they have already said they haven't been able to.
>
> As far as more clearly defining the problem is concerned, here's what is
> probably needed:
>
> a. At least five or six independent high purity signals within a narrow
> frequency range. I typically use a 250 Hz 8-pole filter with DSP set to
> 300 Hz when contesting, but as Eric pointed out many callers are almost
> zero beat with each other. The signals need to be such that sum and
> difference products overlap with other signals within the same passband.
>
> b. The signals need to be injected into the K3 front end with variable
> attenuation and lots of isolation between them so that the test isn't
> colored by the possibility of one signal source pulling the others.
>
> c. The signals need to be keyed, preferably at different speeds from
> each other. Constant tones won't cut it.
>
> d. Assuming that the audio from the K3 was fed into a high quality
> computer sound card, it probably would require some piece of software to
> analyze the recorded wav file to quantify the relative level of the
> undesired products relative to the pure tone inputs. I don't think
> simply viewing on a spectrum analyzer would show anything because of the
> timing dynamics of keying.
>
> Now then, how many hams do you think have the necessary resources to
> recreate those kinds of conditions?
>
> At one point I considered using a program like CW Player to record
> several different CW streams close in frequency, merge them, and then
> feed them into the mic input of a second rig nearby driving a dummy
> load. I didn't follow through on it because the was no way I could
> quantify the possible mixing caused by the second rig before signals
> ever got to the K3, but does that sound like someone who is simply too
> lazy to turn off the AGC???
>
> I'm glad to hear that Elecraft recognizes this as a problem and I am
> anxiously looking forward to whatever they find.
>
> For the record, my parameters that I use for CW are:
>
> AGC DCY = SOFT
> AGC HLD = 0.20
> AGC PLS = NOR
> AGC SLP = 000
> AGC THR = 008
> AGC-F = 140
> AGC-S = 030
>
> I mostly use AGC FAST for contests but change as needed. I never use NR
> or NB at all ... ever.
>
> Dave AB7E
>
>
> On 12/4/2011 1:08 PM, Grant Youngman wrote:
>> What I find most bothersome about these rants, is that somehow certain of the owner class seems to think that Elecraft OWES them a solution or an explanation. As though "mush" is enough of a description for a DSP wizard to have an epiphany and write a few lines of code and fix the problem, which is ill defined and probably difficult to reproduce in the lab.
>>
>> More telling is that it has been pointed out that turning off AGC eliminates the effects. I don't know about these guys, but turning off AGC when the issue is recognized -- since they can clearly recognize it -- sounds like a far more sane and reasonable solution than blaming their contest scores and apparent 'embarrassment' on 'mush' and trying to get some other radio vendor to fix whatever problem shows up in THAT radio.
>>
>> Isn't it reasonable to assume that a 'top contester' should know how to utilize his equipment beyond turning it on and twisting the dial? Geez.
>>
>> Grant/NQ5T
>>
>> Sent from my iPhone
>>
>> On Dec 4, 2011, at 1:44 PM, Mike Fatchett W0MU<[hidden email]> wrote:
>>
>>> I am glad Elecraft is attempting to isolate this with more scientific
>>> data instead of anecdotal comments. Did anyone bother to record any of
>>> the mushiness they are describing? Use the line out and an audio
>>> capture program. I would love to hear what you are hearing.
>>>
>>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

... [show rest of quote]

wayne burdick

Dec 05, 2011; 1:50am

K3 hardware AGC experiment shows promise

Administrator

4620 posts

In reply to this post by dmb@lightstream.net

Hi all,

The K3's hardware AGC time constant is a compromise between recovery
time and IMD due to modulation of the loop. C238, on the bottom of the
RF board near the front, sets this time constant.

We did a little experiment today (thanks to Tree, N6TR) that suggests
increasing the size of C238 substantially might be a worthy change. In
the case of signals just large enough to tickle the hardware AGC, the
first IMD products were reduced by something like 18 dB. This will
also increase the recovery time for very strong signals, so the jury
is out on whether this is OK for the average user.

For the experimentally inclined: C238 is easy to get to; just remove
bottom cover A (the front half). C238 is a large-ish surface mount
capacitor nestled between two 20-pin connectors. The present value is
0.1 uF. Tree tacked a 1-uF cap on top of it. Then he tacked another
one on, which improved things by another few dB.

Some ops have mentioned problems with signals much lower than this,
which has always baffled me. But I got to thinking: Suppose you're
listening to a bunch of S4-S5 signals in your DSP passband. You could
have larger signals outside the DSP, but inside the crystal filter. Or
you could have clicks from strong signals that get inside the crystal
filter but you can't hear because you're using a narrow DSP filter. Or
you could have noise spikes. Any of these could ping the hardware AGC
just enough to cause IMD between all of the signals in the passband.

My point is that increasing the loop time constant could have a more
general benefit when a band is busy and/or noisy.

Let me know if you try this and whether the results are of interest.
(I live in an RF-free zone, it seems, so I can never recreate the
problem here. Frustrating!)

73,
Wayne
N6KR

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David Gilbert

Dec 05, 2011; 1:50am

Re: K3 AGC Mush

827 posts

In reply to this post by alsopb

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
>

wayne burdick

Dec 05, 2011; 1:59am

Re: K3 hardware AGC experiment shows promise

Administrator

4620 posts

In reply to this post by wayne burdick

By the way, we'll be happy to send out these surface-mount 1 uF
capacitors (or whatever we determine is the best value) to anyone who
would like to try the experimental mod, immediately and at no charge.

These are huge as SMD parts go. Anyone with a fine-tip iron would have
no trouble putting one in. There's no need to take the original,
smaller one off; you can just stack the new one on top.

If you're in a hurry, you could use any type of capacitor that will
fit, including an electrolytic. Just be sure to put the (-) end at
ground if you use a polarized capacitor.

73,
Wayne
N6KR

On Dec 4, 2011, at 5:50 PM, Wayne Burdick wrote:

> The K3's hardware AGC time constant is a compromise between recovery
> time and IMD due to modulation of the loop. C238, on the bottom of the
> RF board near the front, sets this time constant.
>
> We did a little experiment today

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wayne burdick

Dec 05, 2011; 2:05am

Re: K3 AGC Mush

Administrator

4620 posts

In reply to this post by David Gilbert

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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Jeff Cochrane - VK4XA

Dec 05, 2011; 2:25am

Re: K3 hardware AGC experiment shows promise

In reply to this post by wayne burdick

CONTENTS DELETED

The author has deleted this message.

Joe Subich, W4TV-4

Dec 05, 2011; 2:36am

Re: K3 hardware AGC experiment shows promise

2826 posts

In reply to this post by wayne burdick

> Some ops have mentioned problems with signals much lower than this,
> which has always baffled me.

Remember, IMD is driven by total *peak* signal level. The peak signal
level is not simply the scalar sum of the levels ... it is a vector
sum as the individual signals add in phase. W8FN explained some of the
constraints in terms of peak to average power of multiple CDMA transmit
signals and IMD ... the same applies to receive signals and the peak
voltage handling capability in the IF amplifier/ADC. Six to 10 S4-S5
signals can create a greater peak voltage (if just for the shortest
time) than a single S9+40 signal.

It's been 25 years since I was exposed to the math behind this (as part
of work in dealing with multiplexed power amplifiers for analog TV) but
it would be instructive to convert the average power levels of a bunch
of S4-S5 signals to P-P voltage, sum those P-P values and convert the
peak voltage back to power levels to see the true impact. Solid state
IF amplifiers and particularly DACs don't have the soft compression
characteristics we were used to with remote cut-off pentodes or even
dual gate MOSFETs in the analog receivers of previous generations.

73,

... Joe, W4TV

On 12/4/2011 8:50 PM, Wayne Burdick wrote:

> Hi all,
>
> The K3's hardware AGC time constant is a compromise between recovery
> time and IMD due to modulation of the loop. C238, on the bottom of the
> RF board near the front, sets this time constant.
>
> We did a little experiment today (thanks to Tree, N6TR) that suggests
> increasing the size of C238 substantially might be a worthy change. In
> the case of signals just large enough to tickle the hardware AGC, the
> first IMD products were reduced by something like 18 dB. This will
> also increase the recovery time for very strong signals, so the jury
> is out on whether this is OK for the average user.
>
> For the experimentally inclined: C238 is easy to get to; just remove
> bottom cover A (the front half). C238 is a large-ish surface mount
> capacitor nestled between two 20-pin connectors. The present value is
> 0.1 uF. Tree tacked a 1-uF cap on top of it. Then he tacked another
> one on, which improved things by another few dB.
>
> Some ops have mentioned problems with signals much lower than this,
> which has always baffled me. But I got to thinking: Suppose you're
> listening to a bunch of S4-S5 signals in your DSP passband. You could
> have larger signals outside the DSP, but inside the crystal filter. Or
> you could have clicks from strong signals that get inside the crystal
> filter but you can't hear because you're using a narrow DSP filter. Or
> you could have noise spikes. Any of these could ping the hardware AGC
> just enough to cause IMD between all of the signals in the passband.
>
> My point is that increasing the loop time constant could have a more
> general benefit when a band is busy and/or noisy.
>
> Let me know if you try this and whether the results are of interest.
> (I live in an RF-free zone, it seems, so I can never recreate the
> problem here. Frustrating!)
>
> 73,
> Wayne
> N6KR
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

... [show rest of quote]

1234