[Elecraft] ALC implementation

[Don Wilhelm]

Richard,

When you put the KX3 into DATA A mode, the mic gain is reduced to 
something resembling Line level.

Depending on your soundcard output, you may still need an attenuator.
Strive for each audio control in the computer and application to be at 
30 to 50%, and then if you have too much audio with the KX3 MIC Gain set 
near its mid-point, then you will have to add an attenuator.

One note on the KX3 - if you drive the audio with too large a signal, 
the mic amplifier will shut down and the MIC GAIN will not work anywhere 
in its range.

73,
Don W3FPR

On 6/28/2019 3:01 PM, Richard Corfield wrote:
> That's interesting thanks. It means that by aiming for no ALC indication
> I've been under modulating.
> 
> I assume the input stage in the KX3 can take higher levels?
> 
> On Fri, 28 Jun 2019, 16:35 Bob McGraw K4TAX, <rmcgraw at blomand.net> wrote:
> 
>> Well written generic paper for operation of FT-8 and other digital
>> signals of like mode.   It does not totally nor correctly apply to
>> Elecraft radios as power management is handled by a totally different
>> means.   And those means and methods suggested in this paper are not
>> applicable to Elecraft radios for power control.   From experience in
>> set-up and operating different radios and different interfaces, I do
>> believe that the WSJT-X operating panel which shows the right slider
>> labeled PWR is very misleading and should be changed to some other
>> description i.e. TX AUD.
>>
>> While many radios use the control of audio level to adjust power output,
>> this is somewhat misleading as there are control areas available such as
>> SPKR level in Windows, and Line Gain for the radios or perhaps an
>> external sound card device.   Again, the use of the acronym MIC is
>> always a frighting term,  in as much as many systems produce a transmit
>> audio level that will overdrive the microphone pre-amplifier input.
>> Once this occurs, reducing MIC gain will not relieve the distorted audio
>> as it occurs pre level control in the circuit.   Frankly, one should not
>> connect the sound card to a microphone input without proper and correct
>> means of attenuating the signal before it is connected to the microphone
>> input.   In addition, this will always preserve the transmit
>> Signal-to-Noise ratio.
>>
>> As to "compression" I take that to mean Speech Processing, which should
>> ALWAYS be off or set to a zero value.   Likewise for EQ, again always
>> set to OFF or FLAT  for transmit and receive purposes as well.
>>
>> As a mater of practice, there are three or perhaps four distinct places
>> that audio levels can be controlled in the transmit path. First is SPKR
>> level which is the audio level out of the computer. Second is the WSJT-X
>> PWR slider, and third is the Line Gain within the radio.  A fourth, if
>> used, would be an external interface such as a Signalink or
>> Soundblaster.   If any of these points end up near minimum value or near
>> maximum value, I strongly suggest further investigation as to why and
>> remedial steps taken to more "normalize" the control values at all
>> points in the system.
>>
>> Some radios do have "meter" indicators which relate to ALC levels while
>> others simply prove a visual means usually the illumination of a LED.
>> In all cases, the indicators should be observed, and the radio operated
>> accordingly with NO indicated ALC action occurring.    Again, regarding
>> Elecraft radios, the first 4 bars on the "ALC Scale" are audio level and
>> NOT ALC action.  The onset of actual ALC occurs at the 5th bar and higher.
>>
>> 73
>>
>> Bob, K4TAX
>>
>>
>>
>>
>> On 6/28/2019 9:18 AM, Andy Durbin wrote:
>>> Does anyone know of any rig that uses "compression" rather than linear
>> gain control to implement ALC?
>>>
>>> ref - https://www.dropbox.com/s/f4uaop5tqwzaweu/FT8Noise6.docx?dl=1
>>>
>>> 73,
>>> Andy, k3wyc
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