WSJT-X Going the Distance – 16,900 km

JT65 QSO with AB1J at some 16,917 km.

JT65 QSO with AB1J at some 16,917 km.

After successfully getting WSJT-X 1.3 up and running last night, I decided to throw out a quick CQ on JT65. Even though my waterfall was showing some interference I still managed to pick up a contact way out over on the West Coast of America some 16,900 kms away!

Other than being my longest QSO to date, what really surprised me was:

  • The fact the QSO was achieved with such high level of interference with the signal barely visible on the waterfall (see below); and
  • That this was with JT65, so imagine what could be achieved with JT9 – shame the majority of activity of the two is JT65!

Looking forward to doing more with WSJT-X!!

Waterfall showing QSO with  AB1J. Note the interference and how weak (visually) the successfully received signal was.

Waterfall showing QSO with AB1J. Note the interference and how weak (visually) the successfully received signal was.

WSJT-X and Windows XP

As mentioned in my post about my first experiences with WSJT-X and JT65/JT9, I had issues getting any version other than 1.1 to successfully decode. A bit more searching and some playing around last night and I now have successfully decoded with 1.2.1 and 1.3 on Windows XP.

My solution in the end was to simply open up wsjtx.ini in the install directory, and then add the following lines at the very end:


This (I understand) has the effect of returning the sampling methods back to what was in version 1.1 – which essentially uses 12kHz sampling rather than 48kHz. There is another option however this is sound card driver specific, and that’s to set the default sampling rate (via the control panel, etc.) to 48kHz. However, for my sound card (Audigy 4) I was unable to find this setting so went with the above solution.

I hope this helps others who may have been stumbling on this. Albeit, I do now realise it’s documented in two places:

  • The above solution is in the manual’s FAQ section – however currently the formatting is a bit askew in the manual; and
  • The details about making sure your sound cards default sampling is set to 48kHz is specified in the Windows install instructions in the manual.

Good luck!

An easy 15,800 with JT9

An easy 15,800 with JT9
JT9 QSO with K8TLC at some 15,813 km.

JT9 QSO with K8TLC at some 15,813 km.

I was passing the shack’s computer last night before dinner and I noticed JT9 showing a very clean waterfall. I saw someone calling but it was really on the edge of my filters passband. So in case someone else was about I threw a CQ out up in a stronger section of my passband.

To my surprise the other caller (K8TLC) saw it and immediately replied. This resulted in a full QSO at some 15,813 km. Full exchange can be seen in the screenshot.

I’ve also found some information on getting WSJT-X versions 1.2 and up working on Windows XP. Seems in my haste I missed the pertinent information in the manual. If all works out I’ll be sure to share.

WSJT-X and DX with JT9 and JT65

Last week I came across JT9 as a mode for DX on HF. I’d not come across it before (possibly being side tracked with WSPR), but before I knew it I was downloading WSJT-X, reading the tutorial and running it up.

However, first attempts to receive were a complete fail. I was sure of success as it was when there was no interference (for once) and I had heaps of JT65 signals roaring in and system time was in sync to ~100 milliseconds. But not a single decode.

I then proceeded to just give it time and let it run some 24 hours. But still nothing…

A bit of searching around the net revealed I wasn’t the only person who had troubles decoding with WSJT-X. Further, it seemed maybe that for those who had troubles all used to work with version 1.1 of WSJT-X.

I proceeded to download WSJT-X 1.1 and lo’ an’ behold suddenly I was decoding signals left right and centre. Both in single JT65 mode (for which there seems greater activity) and also in split mode decoding both JT65 and JT9 transmissions.

Since then I’ve tried again with version 1.3 and also 1.2.1 (a couple of times), but for the sake of me I can not get decodes with either – oh, except a single decode once… And looking on pskreporter (a great site BTW) it would seem very few are using the latest version of WSJT-X. Further, looking at a WSJT-X changelog I note there were changes starting with 1.2 about how the sound hardware was accessed. So I wonder if maybe that’s had a flow on effect to those running on Windows XP (such as my shack PC).

Anyway, at least I have a version that works (just a shame some nice waterfall improvements came in in version 1.2) so I proceeded to try some contacts. My first was with VK5HAM but I made a fair mess of things as I wasn’t as comfortable with the UI as I thought I was. Anyway, the one I was most impressed with was with HA1AD. Details were:

Their grid square: JN87
My grid square: QE37
Mode: JT9
Freq: 14.078850 MHz
Report sent: -06
Report received: -09
Distance: ~12,995
My power: 5W

That is indeed my first true (ie. bi-directional) DX contact.

After that, I was hooked and tried a few more, but often shooting too far (15,000+ kms). It’s amazing how quickly the time passes by with these modes.

So, if you’re yet to try these modes then I highly recommend them. They take WSPR a step further, and with reverse beacon networks such as PSK Reporter you’ve got everything you need (ie. WSPR beaconing but with option for proper QSO contacts)!

One last thing though before I go. Later on my interference returned, but to my surprise WSJT-X kept on decoding. The following two images show WSJT-X picking signals out of the noise. If you take a look at the waterfall @ 23:23 and then just near 1200Hz you can see the signal (just) from ZL3HAM, but at the same time you can see the wonderful interference I enjoy.

Although an extreme example, I have actually had QSOs in amongst lesser interference with WSJT-X this week-end. Something I would have struggled with voice and many other digital modes.

Interference Solution

Interference Solution

Further analysis of my previously  mention interference problems showed two things:

  1. It’s constant (I monitored it with SpectrumLab for a week) and seems to emulate a pattern of a person turning a heater on and off in the mornings and evenings; and
  2. This was not new, as I looked back to one of my 600m mailing list posts around the same time last year where I mistakenly assumed it was due to a change with my mini-whip.

So in a bid to fix it I started to look at Small Magnetic Loops (SMLs).

Using a suitable SML, in theory I should be able to use it’s strong null’s to block interference. So I went about a few ideas but in the end I basically built the amplifier as per PA1M’s page, however I simply re-used the power supply unit for my mini-whip and went with some different loop designs.

Capture showing effects of rotating SML.

Capture showing effects of rotating SML.

Now I’m sure you’ll agree from the image on the right, that the basic principle of a SML’s nulls is working for me. To explain, I started the capture with the loop oriented such that all was well, then in the middle you see when I rotated it such that the interference came back in. Then, at the end I’ve rotated it again to null out the interference.

Interestingly (albeit not surprisingly) the loops orientation is such that it’s radiation pattern is almost perpendicular to that of my dipole.

So, I’m mostly happy as a result.

However! The receive level is well down on the dipoled. For example, without interference and no pre-amp turned on my receiver used to sit at around S7 (and then s9 when the interference kicked in). However now, with the pre-amp on I struggle to see anything on the S meter. 😦

Building the above amp I did use a pair of 2n5109 transistors to ensure all would be well up on the 20m band. However, I fear the biasing network is not setting enough gain for these guys. So I really need to revisit this – or maybe just go and grab one of the commercial offerings.

Lastly, I originally attempted with a loop that was ~1m in diameter and found that on 20m I pretty well had no nulls. Then I remembered that a SML should be no more than 0.1 of the planned wavelength (so ~0.67m for 14.150MHz). So I setup with a 0.5m loop and that’s when I definitely saw the nulls I was after – albeit with degraded receive performance on the lower bands.

Anyway, when I get a chance soon I’ll provide some pics and hopefully also attempt to increase the gain.

SOTA closer for VK7

I don’t always catch the week-end broadcasts, but I was mighty happy that I did this week-end. Here’s the start of the VK7 news:

I am pleased to let you know that the mapping of candidate peaks for VK7 has been completed and checked and the listing has been submitted to the SOTA organisation in the United Kingdom for final checking and uploading into the SOTA watch database.

I will let you know once the final checking has been completed and summit logging can commence.

I can’t wait!! It’s been a big effort by the team mapping all the summits and I for one am very thankful for their efforts.

I’ve been keen on SOTA since I saw the initial mention of SOTA Australia in ‘Amateur Radio’ magazine way back after I got my license – and hence I’ve owned my FT-817ND ever since. It then seemed to stagnate for many years, but suddenly out of the blue it took off with a vengeance, and not long after I left VK1 (for VK7)… VK1 went live. I couldn’t believe it.

But soon, I’ll be able to join in on the action down here. And hopefully, I might even be able to sort out my interference issues at my QTH and do a bit of spotting – but that’s still a work in progress… more soon.