Is it possible that a beat note between tones (and their harmonics) is what’s modulating the ALC reading? If so, moving the tone slightly off the standard pitch may be an acceptable workaround.
Wayne N6KR > On Aug 4, 2017, at 1:42 PM, Wes Stewart <wes_n...@triconet.org> wrote: > > Good find Brian!!! I see it too in FT8. > > This probably explains the great variability in results reported. Some of us > have a problem, others say, Huh, what the heck are you talking about? > > Wes, N7WS > > > On 8/4/2017 11:33 AM, Brian Hunt wrote: >> Here's some followup: >> FLDIGI shows the "pumping" affect with carrier tones of 500, 1000, 1500, and >> 2000 Hz. >> WSJT-X 1.8 shows the "pumping" affect with carrier tones of 1000, 1500 and >> 2000 Hz (couldn't select 500 Hz). >> >> The affect is very narrow with frequency. 10 Hz either way and the output >> and ALC display and MON output is rock solid. Changing the K3 filter center >> frequency has no effect on the above. >> >> 73, >> Brian, K0DTJ >> >> On 8/4/2017 10:58, Brian Hunt wrote: >>> 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 >>> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to wes_n...@triconet.org >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to n...@elecraft.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
