Don of course it is not a power control, that is obvious to me. I am very fortunate to have a lot of RF and Audio test equipment available both at home and at work so I will measure what works best and try to understand why. I will be happy to share my findings. I will of course read your article. I am loathe to use the Windows audio mixer, I would rather use an external passive attenuator. Maybe the Windows mixer has improved, I need to check that with an audio analyser. It used to be awful so I built an external passive attenuator some years ago.
I will be interested to see what happens to the K3S TX composite noise when the power control is used. There is a certain very popular radio where the AM noise comes up by 20 dB when the power is reduced from 100W to 30W. I would be really pleased if the K3S power control works properly! I bought the K3S purely for its TX PN performance. 73 Conrad PA5Y ________________________________ From: Don Wilhelm <donw...@embarqmail.com> Sent: 17 June 2019 16:03:02 To: Conrad PA5Y; elecraft@mailman.qth.net Subject: Re: [Elecraft] Next Question: DATA A with K3s and Fldigi Conrad and all, The POWER control in WSJT-X is a misnomer. It is actually an audio level control. Do NOT use it to control the power with an Elecraft transceiver - set the audio correctly and use the power knob to control the power. While other amateur transceivers can be made to control the power by varying the audio level, that can be disastrous for Elecraft transceiver Power Control. Read the relevant article on my website www.w3fpr.com<http://www.w3fpr.com> for a full explanation. Set the WSJT-X POWER control for 30% to 50% and do the same for the soundcard control in Windows Mixer, then set the LINE IN gain in the K3/S to somewhere near mid-range. By manipulation of those 3 audio level controls, you should be able to achieve the 'magic' indication of 4 bars solid on the ALC meter with the 5th bar flashing - that is the "NO ALC" point for the K3/S, KX3, and KX2 transeivers. The lower 4 bars of the "ALC" meter are there as an aid for setting the audio levels. Set the desired power output with the POWER knob - do NOT vary the audio level. 73, Don W3FPR On 6/17/2019 9:38 AM, Conrad PA5Y wrote: > > Historically there were all kinds of low level artefacts produced by Windows > audio algorithms, including the volume control. This was caused by > insufficient precision leading to truncation artefacts. I have not tested it > for a while and so it may no longer be the case. The result when I did test > it was spectral smearing and some AM on what should be a constant envelope > signal. I trust the power control in WSJT-X far more than that from the > Windows mixer. These effects only really matter during weak signal conditions > when your TX signal is on or near the noise floor. at the receiving station > However they do make your signal wider. > > Also be careful how you vary power, reducing audio carelessly will invariably > decrease the signal to noise on your TX signal which will also affect a > stations ability to receive you. > > My K3S arrives this week and I will make some tests to see exactly what > happens with TX composite noise when power is reduced with the power control > and by reducing audio drive from the PC. Unless someone else has measured > this already? > ______________________________________________________________ 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
