Re: K3 AGC Mush

Posted by Merv Schweigert on Dec 04, 2011; 10:51pm
URL: http://elecraft.85.s1.nabble.com/Fw-CQ-WW-DX-Contest-CW-2011-Unofficial-claimed-scores-tp7060148p7061248.html

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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