Setting up JT modes with the Elecraft KX3

You know me… it won’t take long for me to figure out how to get up and running with digi modes with a new radio! WSJT-X is one of...

You know me… it won’t take long for me to figure out how to get up and running with digi modes with a new radio! WSJT-X is one of the easiest digi mode software programs to configure IMHO. JT65 & JT9 are two of my favorite modes – for good reason too! Very little power can go a long way with the JT modes! I immediately noticed the KX3 can get quite warm if used for more than just a couple QSO’s, so a little USB computer fan helped to dissipate the heat from the heat sink on top of the radio (which does a great job at quickly dissipating the heat). I’ve no clue if this fan is needed or not, I just noticed that it helped maintain a more comfortable temperature, it gets quite hot in my shack up on the second floor exposed to the Southern sun. I imagine on a really hot day with no shade around on a SOTA summit, digi modes might be of concern, but I won’t complain until I have issues! I haven’t upgraded the heat sink like some other users have done, but from what I understand the newer model KX3’s have had that issue fixed. I’ll monitor the temperature closely over the coming weeks. I did receive one comment from another KX3 user that I really should have an isolator in between the rig & the radio, but this USB sound card serves nearly the same purpose as a RigBlaster or Signalink, minus the cables!

Joe Taylor, K1JT is even working on modifying the JT modes a bit by decreasing the transmit/receive time for these modes – see the recent ARRL news article. With quicker turn around times – the JT modes will become even more attractive for folks operating portable (less power consumption) and contesting (quicker contacts)!

I used the KX3 accessory cable packet set (instructions here) that is available through Elecraft – you can purchase your own cables – but individually, they may end up costing you a few more dollars – just spring for the set from Elecraft, you’ll be thankful for the right angle plugs!

ACC1 port on the radio is for the USB to 4 ring 3.5mm adapter cable that is supplied with the radio, this will provide the CAT control for the radio – I prefer to use CAT to key the radio over VOX. You can key the radio using the vox function however. The phone port will be connected to the Mic In (or Line In – usually pink) port on your sound card. I’m confused on whether an external sound card is needed though… from one group of folks, they’ll tell you that you need isolation between your computer and the sound card, so that your sound card doesn’t pick up any artifacts/noise/hum from your computer, but I haven’t noticed any issues, then again how would I? Then another group will tell you to avoid those expensive external USB sound cards… So that’s why i’ve decided to try several different ways – with this external sound card, with the RigBlaster Advantage, and then directly into my Mac Mini Speaker/Line In ports. So far the mini external usb sound card is working great. The Mic port on the radio will be connected to the speaker out (usually green) port on the sound card.

Most reports have indicated to get 3-4 bars of ALC on the ALC meter on the KX3. You’ll do this by activating the “Tune” function button within WSJT-X so you can fine tune the mic gain, and sound card levels so that you have proper ALC indicated. Too much and you’ll distort your signal going out, too little (or negative), will result in less power going out. Not shown, is the ‘Mic Gain’ on the KX3 which was set to 40 on my radio. You can also fine tune the signal levels within WSJT-X by using the slider on the right side, I think this allows for finer tuning than the other controls can provide.

Some other settings you’ll want to adjust will be to turn AGC off, set your receive filter to as wide as it will go (both low cut/high cut). Turn processing and any equalization filters (either RX or TX) off. Set your Baud rate to whatever preferred setting, I just chose the highest – 38400. The USB serial cable was automatically recognized by my Mac Mini – i’m sure it has the FTDI chip in the cable just as my Kenwood cables do. I also prefer to lock the VFO when i’m doing digi modes, you can do this by holding the RATE/KHZ button on the radio for a few seconds.

Make sure to select the USB sound card from within the Audio tab in WSJT-X, once these are set you should start seeing signals from within the waterfall. Don’t forget to sync your time with a time server (for some reason my Mac Mini falls out of sync almost every day by 1-3 seconds & I have to login to the system preferences to reset the clock, I have yet to find a program like Dimension 4 which I use for Windows). (Edit: Apparently there is an issue with ‘some’ Mac Mini computers when placing the computer into sleep mode – it’s possibly a hardware issue. This goes to show that you should verify your time against an accurate source before operating!)

If the levels are too high, you may not even be getting an ALC indication, this is where you’ll have to tinker with the audio out/audio in levels on the sound card. In Windows, the equivalent would be the playback devices menu found by right clicking on your speaker icon in the lower right hand corner. Usually these levels are a bit too high to start with – but each machine & setup is different, you’ll have to find your ‘sweet spot’ for transmitting & receiving clean signals each time. WSJT-X is very forgiving so while you may be decoding something, the idea is to find the signal to noise ratio where WSJT-X decodes the best.

I’ve already received the suggestion to just use ‘DATA A’ mode on the radio which turns all the processing off and equalization, so i’m certainly still discovering new features. A very feature packed radio for sure! Already having loads of fun & made several JT mode contacts today. I can appreciate the lower power settings on the KX3 compared to my 100w radios. With JT modes you really can turn down the power. These settings also apply to WSPR, just keep in mind with WSPR, your transmitting for almost 2 minutes straight, so not sure I’d want to have the power too high. JT modes will transmit for about 50 seconds. As far as setting the audio levels going into your computer, again, every computer is different, so you’ll have to adjust the AF/RF levels on the radio so that your not overloading the input on the PC/WSJT-X instance doing the decoding. I usually try to keep the input level bar on the left at around 10-30db, I find that’s where WSJT-X gets the most decodes (do make sure you’re using the latest WSJT-X v1.7 which has great decoding capability – even multiple decodes!).

A few other caveats – make sure you’ve disabled all system sounds on your computer, else you’ll be transmitting unwanted stuff – especially if you’re using VOX! Easy to do from within the sound settings. Ensure your time is synced properly… for a rough guesstimate I use to verify my system clock – and adjust accordingly – some folks use the WWV signals, others use a software program – so you can imagine where the inconsistencies come from with time sync! Again, WSJT-X is very forgiving in that it will occasionally decode folks who are several seconds out of sync. If you’re on point with the ‘majority’ of signals received, then don’t worry, it’s probably the other station whose clock is off… not yours! I usually won’t respond to folks who are so far off from being in sync because it usually results in a wasted transmission/time. Also, I usually try suggesting to folks that they listen for the first few minutes after WSJT-X has had a chance to decode several rounds of activity, that way you have a more accurate picture of selecting an open area on the waterfall to transmit your signal in, don’t rush in to call CQ only to step on someone else – that’s my digital way of saying ‘is the frequency clear’? 😉 With these practices, JT modes can be a very fun and efficient way of getting lots of DX!

Hope this helps a few folks get up and running on digi modes with their KX3, if at all you ever have any questions, please don’t hesitate to let me know you’re stuck! For me it’s always some small setting somewhere that I forgot to adjust! Big thanks to VE5CAF, KI8DU, K4VBM, KI7GXV, & W0TLR for being my first KX3 JT mode contacts! (20 meters w/ 5 watts).




Digital ModesElecraft KX3JT modesWSJT-X
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