http://elecraft.85.s1.nabble.com/K3-Odd-ALC-behavior-tp7633052p7633086.html
Please post resultd from WSJT-X, as that is what I am using. I have
noted that tune, vs. actual outputs act differently... THANK YOU!
> I spent some quality time with my K3, FLDIGI and an oscilloscope today.
> I had the same problem as described. Looking at my USB soundcard output
> to the K3, the amplitude of the audio from FLDIGI in TUNE mode was rock
> solid. Looking at the MON output from the K3, the level oscillated in
> time with the ALC "pumping" at about 2.4 Hz (timed with a stop watch).
> At the same time the K3 power output into a dummy load was rock solid at
> a selected 10 watts.
>
> Then I changed the carrier frequency in FLDIGI slightly off 1500 Hz and
> the "pumping" went away! At 1515 Hz I could easily set the ALC to the
> desired 4 bars solid, 5th flickering. Then I remembered (and verified)
> that the default filter center in DATA A mode is 1500 Hz. I changed the
> filter center frequency to 1450 Hz and moved the FLDIGI frequency around
> but couldn't reproduce the "pumping".
>
> I plan to repeat the same tests with WSJT-X 1.8 but wanted to get this
> out to the group.
>
> 73,
> Brian, K0DTJ
>
> On 8/3/2017 13:25, Dave Cole wrote:
>> Hi,
>>
>> I have an issue in regards to obtaining 4 bars, and getting the 5th
>> bar of ALC to fluctuate while transmitting JT65.
>>
>> I have plenty of audio, and can drive the ALC to 6 or more bars if I
>> turn things up. However, as I get to 4 bars with the 5th flashing a
>> bit, the ALC starts to fluctuate between nothing and 4 or 5 bars...
>>
>> That is to say, the ALC just goes to zero, no visible ALC, and then
>> teh ALC returns to 4 or 5 bars. This happens across a one or two
>> second time span.
>>
>> The ALC is at zero more than it is above zero most of the time. If I
>> run it to five bars, with the fifth fluctuating, all is well, there
>> seems to be some sort of threshold at the 5th bar of ALC...
>>
>> I have tried a number of things to try and triage this... For instance:
>>
>> 1. Running in "Transmit Test" mode to eliminate RF feedback.
>> 2. Upping the audio level feeding the K3.
>> 3. Reducing the audio level feeding the K3.
>> 4. Upping the line in on the K3 setup.
>> 5. Reducing the Line in on the K3 setup.
>> 6. Adjustment of the WSJT-X output level control, under conditions 2
>> through 5 above.
>>
>> In all cases the above described behavior of the ALC dropping to zero
>> does not change in any way if I am at 5 or less bars. That is to say,
>> if I take the ALC level to 4 bars, it starts dropping to zero more
>> than not...
>>
>> Does anyone have any suggestions as to what this might be?
>>
>> A a bit of history-- the computer and sound card were used on an Icom
>> 756 ProIII, and there was never an issue like this... The ALC was
>> adjustable from zero to too much on the Icom, with no dropouts...
>>
>
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