[Elecraft] ALC adjustment on K3S

[N5XL .]

Sid,

While I am not using a K3 (I am running a KX3/KXPA100), I can give you a general guideline of how I control things here for successful operation in JT.  It should give you a general guideline on what to initially adjust, look for, and set up for your K3 / computer / software package.  

My specifics are a KX3/KXPA100 with Windows 10, no rig interface (kx3 connects to computer directly via audio cables and usb cables) and WJST-X. Antenna is a 40 meter extended double zepp fed with open wire feed for multiband operation.  I make all my JT contacts in DATA mode and not SSB mode, and while I can and have made data contacts in SSB mode, I find it much less worrysome from an ALC settings standpoint to use DATA mode for digital contacts.  I make hundreds of JT contacts on the bands, 40-15 meters mostly.

First, make sure you have your computer and JT software set up to control rig keying correctly.  It is important to make sure the computer, JT software and the K3 all talk together properly and perform as expected with regard to rig keying first.  In WSJT-X, I use cat control to key the radio.  I do not use VOX.

On the radio side, in DATA mode, I have the mic gain on my KX3 at 25.  This is generally where I run the mic gain when I make SSB contacts and should serve as a good initial starting point for you.  Be aware that, at least on the KX3, too high of a mic gain setting will show no ALC indication and can give erratic rig performance regard to TX output stability (what I would call as “power hunting”…a cycling or slow oscillation of ALC indication and indicated power output as the KX3 tries to maintain a stable output).  I would imagine the K3 to be similar.  Generally speaking, err on the low side of mic gain settings as you can easily make ALC fine tuning adjustments for higher ALC within the JT software later.  Once the mic gain on the radio is set where you have solid radio keying and power output performance, do not touch it again in normal JT operation.  You can always come back later after performing the below rough adjustments and make any minor settings for optimal performance later.  As a general guide, once the mic gain is set for good solid operation, you never touch it again.

On the computer side, specifically with regard to the audio slider settings in Windows, I have the Playback device level set at 50 (midscale).  If your soundcard in your computer allows for advanced settings such as audio equalization or audio effects, make sure all of these are turned off.  On the Recording side, it too is set for midscale or 50.  Make sure you have any special audio effects on the recording side turned off.  Pay special attention to any mic gain or boost settings if your soundcard has these features and ensure they are all turned off.  Once set within Windows, I do not touch the audio slider settings again.  There is a lot of variation here with regard to proper audio settings you will end up within Windows due to hundreds of different possible audio cards found in various computers and the final mic gain setting you choose on the K3, but generally speaking, you are looking for non-overdriven audio input as indicted by the ALC display on the K3 with the mic gain set as described above.

In your JT software, you should have some sort of audio sliders that do basically the same thing as the Windows sliders settings.  In WSTJ-X, there are two controls you will use to make the necessary audio fine tuning adjustments.  Set the RX audio input slider so that you have acceptable RX audio levels for good decode.  In WSJT-X, this control can be found on the main program window, on the far left hand side of the display.  I find the best decoding performance to be when the RX audio slider is adjusted so that the software displays a levels of approximately 25-30 dB in RX mode with no stations transmitting (ie, monitoring a quiet band).  This is approximately midscale on the visual display.  Once the RX level is set, you can then adjust your waterfall visual display so that you have whatever visual settings you prefer to see (all of these visual sliders are at the bottom of the WSJT-X Wide Graph window.)  The takeaway here is to have the AF gain settings on the rig and recording audio sliders within Windows to give approximately 30db of indication within WSJT-X.  Fine tuning here can be done within WSJT-X or even with the AF gain control on the K3 if need be.

With regard to TX audio levels in WSJT-X, the slider you want to adjust for proper ALC indication on the K3 is the Pwr slider, found on the far right hand side of the main program window.  Set the Pwr slider to be approximately midscale initially.  Key up the K3 with the TUNE function within WJST-X and while transmitting, slide the slider using your mouse wheel (don’t drag the slider by clicking and holding with the mouse), up or down, to obtain 4 solid bars as displayed on the K3.  It wont take much in the way of adjusting the Pwr slider to obtain the correct ALC indication if the mic gain on the K3 and the Windows audio settings are correct.  Hovering your mouse over the power slider should show you WJST-X’s TX digital gain level.  For my setup, I show approximately -20db, but this exact value will be different for your specific rig settings and computer audio settings.  I generally like to see the Pwr slider about midway of the scale.  This gives you ample adjustment, up or down, as needed to get the ALC as displayed on the K3 correct.  The general takeaway at this step is that you want your K3 mic gain and Windows playback audio sliders set so that you use approximately a midscale level on the Pwr slider in WSJT-X in order to give a good ALC indication on the K3.

After the initial adjustments described above, make all of your fine tuning ALC settings for the K3 through WSJT-X.  Don’t touch the mic gain setting on the K3 or touch the Windows audio sliders.  The Pwr slider in the WSJT-X software has a much better fine tuning control of the ALC settings displayed on the K3 than  you can obtain with either the radio or within Windows.  As you change bands, and even as you change specific audio TX frequencies within the waterfall display, monitor the ALC display on the K3 and use the WJST Pwr slider to make any minor fine tuning adjustments for proper indication of ALC.  Once its all set correctly, it only takes one or two mousewheel indent rolls, up or down, to bring ALC into the correct level.  The main thing to takeaway with this approach of ALC control is that you have better fine tune level of control of ALC indication using the WSJT Pwr slider as the WSJT’s slider is not nearly as sensitive and touchy as trying to control ALC via the KX3’s, (and likely the K3’s) mic gain.  You’ll have better fine adjusting of ALC control overall using this approach.

One last general comment.  I know the instructions on setting the ALC level for proper transmit in DATA mode say to look for 4 solid bars and the 5th bar to be flickering.  In my experience in operating JT modes heavily for several months, I have found the best performance in making contacts is to set the ALC for 4 solid bars and not worry about a flickering 5th bar.  If I happen to see the 5th bar flickering, that’s fine and I don’t worry about adjusting it lower, but I always shoot for at least 4 solid bars and find it to be a solid performing setting when making JT contacts.  When set this way, I have just the occasional flicker of a 5th ALC bar...sometimes I may see an occasional flicker the 5th bar, but most of the time I don’t see any 5th bar flicker.  If I have been playing around with rig settings or other computer settings and I need to get things back to a stable value for JT operation, its always done first by making sure I have the general mic gain and windows audio slider set as I outlined above.  I make any necessary final ALC adjustments with the Pwr slider in WSJT.  It never takes more than a mousewheel roll one way or another to bring it right back where I want it.

Hope this helps and here’s hoping to see you on the waterfall!

73
Dave, N5XL



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