[Elecraft] K3 original - ALC erratic

[Martin Sole]

I don't propose to know the full details but I would assume that being 
an SDR the K3 digitises the audio at some point. If the sampling rate 
and the audio frequency have the right relationship then you can expect 
to see those fluctuating effects. I have seen this when making 
distortion measurements on AM radios since the sampling rate and the mod 
are not phase locked these odd aliasing type effects occur. Moving the 
modulation frequency even just a few Hz is usually enough to achieve a 
rock steady reading.

Martin, HS0ZED


On 16/09/2019 19:09, Bob McGraw K4TAX wrote:
> With my K3S I do find there is a relationship or interaction with the 
> scan rate of the ALC display and the frequency of the tone supplied by 
> FT-8.   Specifically 1500 Hz will appear to have fluctuating ALC 
> display while the actual level is not changing. By setting the tone, 
> TUNE is a good application to do this, to some value higher or lower 
> than 1500 Hz will eliminate the display fluctuations.   WSJT defaults 
> to 1500 Hz for TUNE mode.
>
> Also if the Line Gain set via the MIC level control is less than 25 or 
> so, the granularity of the adjustment becomes critical.   It is 
> suggested to lower the PWR slider on the WSJT application and raise 
> the value for the Line Gain to some value between 30 and 40.  This 
> also applies to the value of SPKR level from the computer.  Again 
> typically 30 to 40 are good values giving smooth level resolution and 
> changes.
>
> 73
>
> Bob, K4TAX
>
>
> On 9/15/2019 10:28 PM, David Bunte wrote:
>> Jim -
>>
>> I have no answer, but mine has always been extremely critical. I can 
>> set it
>> for 4 bars... and it won't budge... but I can't set it for the 5th bar
>> blinking... it goes from 4 solid to 5 solid no matter how much I play 
>> with
>> the various level controls. I don't do a lot of digital work, so I am 
>> not
>> really too concerned. There may be something I am missing, but I just 
>> leave
>> it at 4 bars and hope for the best.
>>
>> Dave - K9FN
>>
>> On Sun, Sep 15, 2019 at 11:25 PM Jim Miller <JimMiller at stl-online.net>
>> wrote:
>>
>>> K3 original - ALC erratic
>>>
>>> Noticeable on digital mode(s?) (FT8).  The ALC  - set at 4 solid and 
>>> 5th
>>> flashing - is far more critical than I remember. Seems like I could 
>>> easily
>>> set it exactly where I wanted it and it would stay there.  Now not so.
>>> Just wondering what can affect the adjustment to where it will drop 
>>> to 2
>>> bars sometimes and the small change of the "mic" gain will make it 
>>> higher
>>> than wanted.  Not sure it is a continuous condition.  Just far more
>>> critical
>>> than usual.
>>>
>>> Thanks, Jim KG0KP
>>>
>>>
>>>
>
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